The Umbilical Cord

No named scholar was found calling the umbilical cord bad design. A cord loops the neck or body in a fifth to a third of births and rarely harms. Short and long cords both raise perinatal death, so length is a trade-off. In horses, cord problems are the commonest diagnosed cause of lost foals.

By AI (Claude Opus 5.5, reasoning effort unavailable) Draft:  September 2026

"Antenatal nuchal cords usually occur randomly with increased frequency in late gestation and appear to be a normal part of intrauterine life that is rarely associated with perinatal morbidity and mortality." — James Clapp and colleagues, American Journal of Obstetrics and Gynecology, 20031

Summary

The parent article, The Human Body Under Criticism, splits every bad-design complaint into three claims:  the part fails often, a better build exists, and history explains the layout.  This article tests the umbilical cord, which is long enough to wrap around a baby's neck.

  • Who makes the complaint. No published scholar was found calling the cord a design flaw. Nathan Lents's Human Errors (2018) mentions it once, for breech births.2 Wenda Trevathan uses the looped cord to explain why human mothers need help at birth.3 The flaw version was found only in an anonymous 2010 blog comment.4
  • Length. At 40 weeks the median Norwegian cord is 57.5 to 62.1 cm, and tension from fetal movement helps set the length.56
  • Frequency. A cord around the neck or body is found at 14.7% to 33.7% of births, and more often late in pregnancy.178
  • Harm. Large cohorts find no clinically significant harm among babies born alive, and the largest US stillbirth study does not count a nuchal cord alone as a cause of death.91011 Norway's registry gives, at most, one extra death per 770 entangled term births.612
  • Short cords. Cords below the 10th percentile come with more abruption, breech, caesarean and perinatal death. Cords above the 90th come with fewer of the first three and more deaths.66 Both tails cost lives, which is the shape of a trade-off.
  • Practice. Studies advise against inducing labour or scanning for a nuchal cord. At delivery the loop is slipped off, or the baby is delivered with a "somersault" that keeps the cord intact.7813
  • Other mammals. In horses, cord problems are the most common diagnosis among lost foals sent for examination.14
  • The design side has not addressed the cord at all.

Verdict:  the complaint fails as a claim that the cord fails often, and the obvious redesign, a shorter cord, is measured and carries its own deaths.  The design reply is weakest on the spread of lengths:  both tails kill, a knot combined with a loop multiplies perinatal death nearly tenfold at term, and no one has explained why the length is not held in a narrower range.

Part 1: Who makes the complaint

The search for the complaint's authors came up nearly empty.

Nathan Lents.  Human Errors is the most complete recent list of human "glitches."  A search of its full text for "umbilical" returns one passage, about breech births:  "Much of the risk to baby is due to a tenfold higher risk of constriction of the umbilical cord, which deprives the baby of oxygen."2  Lents blames the breech position, not the cord.  Searches of Lents for "nuchal," and of Jerry Coyne's, Richard Dawkins's and Neil Shubin's popular books for "umbilical," return nothing.15

Wenda Trevathan.  Trevathan, an anthropologist who studies birth, argues that a human baby usually emerges facing away from its mother, so the mother cannot easily reach it:  "If the umbilical cord is wrapped around the neck (referred to in medical texts as a nuchal cord ) as it is in approximately 23–33% of births [ 31 ], she may also find it difficult to remove it before the baby is expelled further (and possibly strangled) with the next contraction."3  This explains why human mothers seek help at birth.  It gives no rate for strangling and does not call the cord badly built.

The popular complaint.  The design-flaw version was found in a reader comment under a 2010 post by the biologist P. Z. Myers, "Design flaws support evolution":  "There's something very poorly designed in humans and accidental death by way of the path of sustainence... first the cord, then eating... it's silly."4

The strongest form.  The cord is longer than the distance it spans, so it can loop around the neck.  A loop can tighten in labour and cut off the baby's blood.  Cord problems are a probable or possible cause of about one US stillbirth in ten.9  A designer could have made a cord that cannot loop, or cannot be squeezed shut.  Parts 2 to 5 test each step.

Part 2: How long the cord is, and what sets its length

The numbers.  The best reference data come from the Medical Birth Registry of Norway.  Lorentz Erland Linde and colleagues at the University of Bergen built percentile charts from 797,096 cords measured at birth between 1999 and 2013.6  At 40 weeks:

Group 5th 10th Median 90th 95th
First birth, girls 39.7 43.4 57.5 75.8 82.7
First birth, boys 41.7 45.7 59.3 77.7 85.4
Later birth, girls 41.4 45.3 59.9 78.3 85.2
Later birth, boys 43.2 47.4 62.1 82.1 85.4

All values are in centimetres.6  A Tokyo hospital series of 11,029 births found a mean of 56.2 cm with a standard deviation of 11.7 cm, and a range from 19 to 133 cm.16  So "short" and "long" are statistical cut-offs, not fixed lengths.  Studies use the 10th and 90th percentiles, or about 1.5 standard deviations, which at term means roughly under 38 to 47 cm and over 74 to 82 cm.166

The cord keeps growing to term.17

What sets the length.  Three lines of evidence point to tension from fetal movement.

  • In 1981 M. E. Miller, M. Higginbottom and D. W. Smith found short cords in newborns whose movement had been limited, by early crowding in the womb or by limb defects. They concluded that "umbilical cord growth occurs in response to tensile forces relating to intrauterine space availability and fetal movement during early development."18
  • In 1982 A. C. Moessinger and colleagues tested this in rats. Fetuses held still by too little amniotic fluid grew cords 65% to 78% of their littermates' length, and fetuses paralysed with curare grew cords 85% as long. Fetuses placed free in the mother's abdomen, still attached, grew cords "measuring 147% of littermate controls." The authors concluded that "tensile forces on the cord secondary to fetal movements are important determinants of cord length."5
  • Boys have longer cords than girls after about 28 weeks, which Linde's group links to the "stretch hypothesis," while noting that it is "disputed."6

Maternal height, weight, parity and diabetes also lengthen it.6  So the length is at least partly a response to how much the fetus moves.  An active fetus gets more slack, and the same slack lets it loop the cord around itself.

Part 3: How often the cord wraps the neck, and what it does

How often.  Every large series finds a loop at a large share of births:

  • Soroka Medical Center, Israel, 1988 to 2003: 14.7% of 166,318 deliveries.8
  • Norway, 1999 to 2013: 20.7% of 856,300 births, counting loops around the neck or any other body part.6
  • Intermountain Healthcare, western United States, 2005 to 2010: 6.6% tight and 21.6% loose, 28.2% in all, of 219,337 live births.10
  • Zurich, 1995 to 2004: 33.7% of term and 35.1% of post-term planned vaginal births.7

Two or more loops are less common.  J. D. Larson's Oklahoma series found them at 3.8% of 8,565 term deliveries, and the Zurich series at 5.8%.197  James Clapp's group scanned the same fetuses repeatedly in a blinded study.  The rate "rose with advancing gestation from 12% at 24 to 26 weeks to 37% at term," and at each age the loop was "a random or chance event."1

What it does to live-born babies.  The large cohorts agree that a loop does not measurably harm babies born alive.

  • Eyal Sheiner's group, at Soroka Medical Center in Israel, found perinatal mortality lower with a nuchal cord: 11 per 1,000 against 16 per 1,000.8 This is probably selection: a cord recorded at a normal birth belongs to a baby that reached one.
  • The same group's larger follow-up of 243,682 deliveries found perinatal mortality of 0.5% with a nuchal cord and 0.6% without (p = 0.16), and no rise in long-term heart or lung illness.1111
  • Henry, Andres and Christensen tested tight cords, defined as loops that cannot be slipped over the head.10 Term babies with one were admitted to intensive care at 6.6% against 5.9%, but were not more likely to need a transfusion "or to die."10 They judged every difference "too small for clinical significance."10
  • Multiple loops bring more meconium, more abnormal heart-rate tracings and more forceps deliveries, "however, there was no added risk of an adverse neonatal outcome."19

A loop does squeeze the cord during labour.  The Zurich group found worse cord blood gases with every kind of nuchal cord, but no more low Apgar scores and no more intensive-care admissions.7  Morarji Peesay's 2017 review describes tight loops that leave a baby with a dusky face and low blood pressure.20  The harm is real in a minority and absent on average.

What it does before birth.  Henry's cohort counted live births only, so it cannot see a baby who died in the womb.  Two sources can.

The Stillbirth Collaborative Research Network examined 512 stillbirths in 59 US hospitals from 2006 to 2008, with full postmortems.  Cord problems were a probable or possible cause in 53, or 10.4%.9  Its criteria were strict, and "Nuchal cord alone was not considered a cause of death."9  With US stillbirth at about 1 in 160 pregnancies, all cord causes together come to about 1 in 1,540 pregnancies, and that total includes vasa previa and prolapse, which have nothing to do with length.921

The Norwegian registry is the one cohort that found a raised death rate.  At term, perinatal death was 0.31% with a cord entangled around the neck or body and 0.18% without, an odds ratio of 1.72.6  If all of that difference were caused by the loop, it would come to about one extra death per 770 entangled term births, or about 0.27 per 1,000 of all term births.12  The registry could not say whether a loop was around the neck or the body.6  A loop plus a true knot, found in 0.43% of births, carried an adjusted odds ratio for perinatal death at term of 9.77.6

So a loop is common, usually harmless, and rarely fatal.  A knot is far more dangerous, and long cords knot more.

Part 4: The short cord's own risks

The obvious redesign is a shorter cord, one too short to loop.  That cord has been measured, because about one baby in ten is born with one.

Placental abruption.  In Norway, cords below the 10th percentile came with placental abruption, the placenta tearing away from the womb before birth, in 0.53% of births against 0.34%.  Linde's group writes that their study "is large enough to confirm that a short cord is associated with a 50% increased risk of abruption in the total population ( Table 3 ), and a doubled risk at term."6  An abruption is dangerous to both mother and baby.  The US stillbirth study found it among the causes of 7.4% of stillbirths.9

Failure to descend and turn.  The data fit the picture of a baby tethered as it turns and descends.  With a short cord, breech position rose from 3.34% to 5.91%, emergency caesarean from 8.68% to 14.39%, and manual removal of the placenta from 1.35% to 1.82%.6  Paula Krakowiak's Washington State study of 3,565 short-cord births found more forceps and vacuum deliveries (relative risk 1.4), more retained placentas (1.6) and more fetal distress (1.8).22

Rupture.  Peesay's review cites a 1973 study finding that the cord stretches "up to 12.5% of its length" and breaks under "around 10–14 lbs."20  No population rate of rupture was found, so this is the weakest of the short-cord risks here.

Death.  Short cords came with perinatal death in 0.67% of births against 0.46%, and intrauterine death in 0.47% against 0.35%.6  Krakowiak found term infants with short cords had 2.4 times the risk of death in the first year.22  Part of this is not the cord's fault:  short cords come with more malformations and smaller babies, and a baby that moves less grows a shorter cord.18226  A short cord is partly a sign of a fetus already in trouble.

Long cords.  Cords above the 90th percentile came with fewer abruptions (0.23% against 0.37%), fewer breeches (2.21% against 3.69%) and fewer caesareans (10.28% against 15.52%).  But they came with more perinatal deaths:  0.83% against 0.44%.6  Long cords knot and loop more.

The authors' summary:  "Both short and long cords were associated with increased risk of adverse outcome for the fetus and the mother, also after adjustment for important confounders."6  Each tail raises perinatal death by a few per thousand births in that tail.23  Moving the whole range shorter would reduce loops and knots and raise abruption, breech and failed descent.  Moving it longer would do the reverse.

Part 5: What obstetrics does about it

Before labour.  The studies that looked argue against acting on a nuchal cord before birth.

  • Sheiner's group: "labor induction in such cases is probably unnecessary."8
  • The Zurich group: "Nuchal cords do not influence clinical management at delivery, and neonatal primary adaption is not impaired. Our data show that ultrasonographic nuchal cord assessment is not necessary at the time of admission for delivery."7
  • Ultrasound finds the loop poorly. E. Peregrine and colleagues in London scanned 289 women before induction: "The sensitivity of ultrasound in diagnosing a nuchal cord was 37.5%," and a loop did not significantly raise the caesarean rate (35% against 28%).24 Linde's group agrees that prenatal scanning for cord problems "is hampered with low sensitivity and specificity."6

No trial was found showing that finding a loop before labour, and acting on it, saves lives.  No American (ACOG) or British (RCOG) guideline on nuchal cord was found;  the RCOG's cord guideline covers prolapse.15

At delivery.  A loose loop is slipped over the baby's head.  For a tight loop, a 2015 review in American Family Physician gives two options:  "A tight nuchal cord can be clamped twice and cut before delivery of the shoulders, or the baby may be delivered using a somersault maneuver in which the cord is left nuchal and the distance from the cord to placenta minimized by pushing the head toward the maternal thigh."13  Judith Mercer and colleagues argue for the somersault, because "Cutting the umbilical cord before birth is an intervention that has been associated with hypovolemia, anemia, shock, hypoxic-ischemic encephalopathy, and cerebral palsy."  They also admit that "Evidence for specific management techniques is lacking."25

So the medical answer is mostly to leave the loop alone, and the main harm the literature warns about is cutting it too soon.

Part 6: The design replies, and the price of each build

What the design side has said.  Nothing that was found.  Searches of Creation Ministries International, Answers in Genesis, the Institute for Creation Research and Evolution News found no article on the nuchal cord or cord length, and none of the design replies in the parent article mentions the cord.15  The nearest thing comes from two Japanese obstetricians, Shunji Suzuki and Yukiko Fuse, who were not writing about design.  They suggested that "fetal movement produces a tension on the cord that creates ample free length for delivery plus the length of the wrapped cord," and that "the excessively long cord may have self-protective effects."16  The first rests on a pathology practice's web page, the second is a conjecture, and the Norwegian data, with more deaths among long cords, do not support it.

The parent's three claims, applied.

  1. The part fails often. It does not. A loop is found at a fifth to a third of births, does no clinically significant harm among live births, and is not counted alone as a cause of stillbirth. The one cohort to find harm gives about 1.3 extra deaths per 1,000 entangled term births, as an upper bound.12
  2. A better build exists. No one has drawn one. A shorter cord is measured, and costs more abruption, breech, caesarean and perinatal death (Part 4). A cord that resists squeezing already exists: its Wharton's jelly "is supposed to protect against constriction due to fetal grasping, labor contractions, knots, kinks, or loops."20 A cord held to one fixed length is the strongest proposal, discussed below.
  3. History explains the layout. No critic argues that the cord's length is an evolutionary leftover. All placental mammals have cords, and horses have the same failures. K. E. Whitwell found that "In 95% of normal Thoroughbred foals the cord measures less than 84 cm," and that "Increased length is the most common abnormality and predisposes to three potentially lethal conditions, strangulation of the cord around the fetus, excessive torsion, and allantochorionic necrosis at the cervical pole."26 In 1,252 British equine losses sent for diagnosis, cord problems were the most common finding, at 38.8%.14 Nothing about the human cord points to a human ancestor.

Where the design reply is weakest.  Cords at term range from 19 to 133 cm.16  Both tails carry measured deaths, and a system that held every cord near the median would lose fewer babies at both ends.  The reply is that length tracks fetal movement, and an active fetus needs more slack.  But no study has shown the present spread is the narrowest that could serve every fetus.  The knot is the other weak point.  A loop plus a true knot, found in 0.43% of births, carries an adjusted odds ratio of 9.77 for perinatal death at term.6

Objections and responses

  • "One stillbirth in ten is caused by the cord. That is not rare." Stillbirth is about 1 in 160 US pregnancies, so 10.4% of stillbirths is about 1 in 1,540 pregnancies.21 That total includes vasa previa and prolapse, which a shorter cord would not prevent, and excludes the nuchal cord alone.9
  • "The live-birth cohorts cannot see babies who died." True of Henry's study. Sheiner's, Masad's and Linde's count perinatal deaths, which normally include stillbirths, and only Linde's found a raised rate. That rate is used here as the upper bound, although the registry pools neck and body loops and its authors say they "cannot infer" cause for some associations.6
  • "Tight cords are the dangerous ones, and averages hide them." Henry's group studied tight cords separately and found no excess of deaths.10 Peesay's review shows that single tight cords can harm.20 Harm occurs in individual cases and does not show in the totals.
  • "A designer would not allow even one strangled baby." That is an argument about suffering, not layout. The young-earth answer, that death and decay came after the Fall, covers it only by assertion, and no creationist has applied it to the cord.
  • "The horse comparison proves common descent." Common descent and a common designer both predict a shared cord and shared failures. The comparison answers the claim that the human body is uniquely bad, not the question of origin.

Issues and unanswered questions

  • Abstracts only. Sheiner 2006, Henry 2013, Krakowiak 2004, Naeye 1985, Schäffer 2005, Peregrine 2005 and the equine papers were read as abstracts. Linde 2018, the stillbirth network paper and Suzuki 2012 were read in full.
  • Association, not cause. Every outcome here is observational. Short cords come with small and malformed babies, so part of their excess death belongs to the baby, not the cord.
  • Neck or body. No population study was found that separates a neck loop's own risk of stillbirth from a body loop's.
  • No guideline found. The search found no ACOG or RCOG nuchal cord guideline. That is a search result, not proof that none exists.
  • A number in the leading review. Peesay attributes nuchal cord rates of "6% at 20 wks GA and 29% at 42 weeks" to Larson 1995, but Larson's cohort was term deliveries only.20 This article uses Clapp's scanned series instead.
  • Silence on the design side. Every design reply here is this article's, not a creationist's. Whether a narrower range of cord lengths is achievable, given how much fetal activity varies, is unstudied.

Verdict

The complaint that the umbilical cord is badly designed because it can wrap the neck fails on its main premise.  A cord around the neck is present at about a fifth to a third of births, and large cohorts find it does not measurably raise death or illness among babies born alive.  The largest US stillbirth study does not count it alone as a cause of death, and the one registry that found a raised death rate gives, at most, one extra death per 770 entangled term births.

The redesign the complaint implies, a shorter cord, is not hypothetical.  About one baby in ten has one, and it comes with more abruption, breech births, caesareans, retained placentas and perinatal deaths.  Long cords carry the opposite set of risks.  Costs at both ends and a middle that works are the signature of a trade-off.  The problem is also not human:  in horses, cord problems are the commonest diagnosis among lost foals.

The design reply is weakest on the spread of lengths and on knots, and the design side has not answered the complaint at all.  But no scholar has made the complaint either.  On the evidence, the cord is a trade-off, and "bad design" is not supported.

Sources

  1. 1.

    Clapp, James F. et al.  “The natural history of antenatal nuchal cords.”  American Journal of Obstetrics and Gynecology 189(2):488–493.  Aug 2003.  Read from the PubMed abstract (PMID 14520223);  full text paywalled.

    1. 1a.

      Section Abstract, Results:  “The incidence of nuchal cord rose with advancing gestation from 12% at 24 to 26 weeks to 37% at term. However, at each gestational age, its occurrence was a random or chance event and was not associated with clinical evidence of fetal compromise before labor.” ↩ ↩

    2. 1b.

      Section Abstract, Conclusion:  “Antenatal nuchal cords usually occur randomly with increased frequency in late gestation and appear to be a normal part of intrauterine life that is rarely associated with perinatal morbidity and mortality.” ↩

  2. 2.

    Lents, Nathan H.  Human Errors: A Panorama of Our Glitches, from Pointless Bones to Broken Genes.  Houghton Mifflin Harcourt.  2018.  Print-disabled archive.org item read by the search-inside route;  not stored.  Mirror:  Archive.org

    1. 2a.

      Page 111:  “Much of the risk to baby is due to a tenfold higher risk of constriction of the umbilical cord, which deprives the baby of oxygen.”  Leaf 131;  printed page = leaf − 20 in the body, from the BookReader leaf map and the index entries used in the parent article. ↩ ↩

  3. 3.

    Trevathan, Wenda.  “Primate pelvic anatomy and implications for birth.”  Philosophical Transactions of the Royal Society B 370:20140065.  2015.  Mirror:  PMC

    1. 3a.

      Section 6. Are humans unique in having assistance at birth?:  “If the umbilical cord is wrapped around the neck (referred to in medical texts as a nuchal cord ) as it is in approximately 23–33% of births [ 31 ], she may also find it difficult to remove it before the baby is expelled further (and possibly strangled) with the next contraction.”  Reference 31 is Williams Obstetrics (2010), The newborn infant, pp. 595–598. ↩ ↩

  4. 4.

    Myers, P. Z.  “Design flaws support evolution.”  Pharyngula, ScienceBlogs.  Mar 31, 2010.  The quotation is from an anonymous reader comment (Yahoo sign-in, marked "not verified") posted 31 March 2010, not from Myers.  Spelling as printed.

    1. 4a.

      Section Comments:  “There's virutally no such thing as a premature birth or complication like an umbilacle cord getting wrapped around the child's neck, choking it to death. (There's something very poorly designed in humans and accidental death by way of the path of sustainence... first the cord, then eating... it's silly.)” ↩ ↩

  5. 5.

    Moessinger, A. C. et al.  “Umbilical cord length as an index of fetal activity: experimental study and clinical implications.”  Pediatric Research 16(2):109–112.  Feb 1982.  Read from the PubMed abstract (PMID 7036074).  Rat experiments.

    1. 5a.

      Section Abstract:  “The mean cord length represented 65% of littermate control values when persistent oligohydramnios was induced on day 15, 71% for day 16 and 78% for day 17 (term day 21). … The paralyzed fetuses with polyhydramnios had a mean cord length representing 85% of sham operated controls … Extra-uterine pregnancies with the fetuses free in the maternal abdominal cavity, yet attached to their umbilical cords, led to cords measuring 147% of littermate controls. … These results indicate that tensile forces on the cord secondary to fetal movements are important determinants of cord length.” ↩ ↩

  6. 6.

    Linde, Lorentz Erland et al.  “Extreme umbilical cord lengths, cord knot and entanglement: Risk factors and risk of adverse outcomes, a population-based study.”  PLoS ONE 13(3):e0194814.  Mar 27, 2018.  CC BY.  Medical Birth Registry of Norway, 1999–2013.  Full text and S1 Table read.  Mirror:  PMC

    1. 6a.

      Section Methods:  “The length of the umbilical cord was measured in centimetres. … To construct empirical percentiles of cord length for the population we included cord lengths from 1 to 290 cm ( n = 797 096).” ↩

    2. 6b.

      Table S1:  “Gestational age (weeks), parity (0. 1+) and gender specific empirical umbilical cord length (cm) percentiles”.  Row for 40 weeks.  Median, 5th, 10th, 90th, 95th:  para 0 girls 57.5, 39.7, 43.4, 75.8, 82.7;  para 0 boys 59.3, 41.7, 45.7, 77.7, 85.4;  para 1+ girls 59.9, 41.4, 45.3, 78.3, 85.2;  para 1+ boys 62.1, 43.2, 47.4, 82.1, 85.4. ↩ ↩ ↩

    3. 6c.

      Section Results, What influences the risk of entanglement?:  “The occurrence of umbilical cord entanglement at birth was 20.7% ( Table 1 ).”  The registry's tick box reads "entanglement (around the neck or other body parts)" (Methods). ↩

    4. 6d.

      Table 3:  “Odds ratios of adverse pregnancy outcomes in pregnancies with a short umbilical cord”.  Short cord against not short:  abruptio placentae 0.53% vs 0.34%, OR 1.54;  breech 5.91% vs 3.34%, OR 1.74;  emergency caesarean 14.39% vs 8.68%, OR 1.65;  caesarean 22.81% vs 14.33%, OR 1.73;  manual removal of placenta 1.82% vs 1.35%, OR 1.30;  perinatal death 0.67% vs 0.46%, OR 1.50 (1.36–1.65);  intrauterine death 0.47% vs 0.35%, OR 1.37;  malformation 5.92% vs 4.32%, OR 1.40. ↩ ↩ ↩ ↩

    5. 6e.

      Table 4:  “Odds ratios of adverse pregnancy outcomes in pregnancies with a long umbilical cord”.  Long cord against not long:  abruptio placentae 0.23% vs 0.37%, OR 0.63;  breech 2.21% vs 3.69%, OR 0.62;  caesarean 10.28% vs 15.52%, OR 0.62;  perinatal death 0.83% vs 0.44%, OR 1.83 (1.67–2.00).  Section Abstract, Results:  “Increasing parity, maternal height and body mass index, and diabetes were associated with increased risk of a long cord.” ↩ ↩ ↩

    6. 6f.

      Table 5:  “Odds ratios of adverse pregnancy outcomes in pregnancies with cord entanglement”.  Perinatal death at term:  530 of 170,262 with entanglement (0.31%) against 1,161 of 639,259 without (0.18%), OR 1.72 (1.55–1.90). ↩ ↩

    7. 6g.

      Section Results, Combined knot and entanglement:  “The combination of cord entanglement and knot occurred in 3698 births (0.43%). … For gestational age 37–41 and 28–36 weeks the effect of the combination of cord entanglement and knot was more than additive with aORs of perinatal death 9.77 (95%CI 7.57–12.60) and 5.90 (95%CI 3.92–8.87), respectively.” ↩ ↩

    8. 6h.

      Section Discussion:  “our study is large enough to confirm that a short cord is associated with a 50% increased risk of abruption in the total population ( Table 3 ), and a doubled risk at term.” ↩

    9. 6i.

      Section Discussion:  “Both short and long cords were associated with increased risk of adverse outcome for the fetus and the mother, also after adjustment for important confounders.” ↩

    10. 6j.

      Section Discussion:  “Because of lacking information on number of loops and of which body parts the cord was entangled, we were unable to study whether nuchal entanglement or the number of loops influence risks.”  “We cannot infer from our study whether cord entanglement contributes to growth restriction, or the other way around.” ↩ ↩

    11. 6k.

      Section Discussion:  “Although disputed [ 9 ], the “stretch hypothesis” which says that tensile force is an important determinant for cord length [ 29 ] suggests that an active fetus develop a longer cord.”  Reference 9 is Krakowiak 2004. ↩

    12. 6l.

      Section Discussion:  “Prenatal identification of these abnormalities with ultrasound is hampered with low sensitivity and specificity, and the results may cause unnecessary worries and frustration for the mother and the clinician [ 23 , 24 ].” ↩

  7. 7.

    Schäffer, Leonhard et al.  “Nuchal cords in term and postterm deliveries: do we need to know?”  Obstetrics and Gynecology 106(1):23–28.  Jul 2005.  University Hospital Zurich.  Read from the PubMed abstract (PMID 15994613).

    1. 7a.

      Section Abstract, Results:  “The incidence of nuchal cords in term and postterm deliveries was 33.7% and 35.1%, respectively. Multiple nuchal cords were present in 5.8% of term and 5.5% of postterm deliveries. … Unfavorable neonatal blood gas values were significantly more frequent in all nuchal cord groups. Nevertheless, 5-minute Apgar scores less than 7 were not more common, and admission to neonatal unit was not required more frequently.” ↩ ↩ ↩ ↩

    2. 7b.

      Section Abstract, Conclusion:  “Nuchal cords do not influence clinical management at delivery, and neonatal primary adaption is not impaired. Our data show that ultrasonographic nuchal cord assessment is not necessary at the time of admission for delivery.” ↩ ↩

  8. 8.

    Sheiner, Eyal et al.  “Nuchal cord is not associated with adverse perinatal outcome.”  Archives of Gynecology and Obstetrics 274(2):81–83.  2006.  Soroka University Medical Center, 1988–2003.  Read from the PubMed abstract (PMID 16374604).

    1. 8a.

      Section Abstract, Results:  “Of 166,318 deliveries during the study period, 14.7% had a nuchal cord, documented at birth (n=24,392).”  “the perinatal mortality rate was significantly lower in pregnancies with nuchal cord as compared with the comparison group (11/1,000 vs. 16/1,000; OR=0.7, 95% CI 0.6-0.8, P=0.001).” ↩ ↩ ↩

    2. 8b.

      Section Abstract, Conclusions:  “Nuchal cord is not associated with adverse perinatal outcome. Thus, labor induction in such cases is probably unnecessary.” ↩ ↩

  9. 9.

    Stillbirth Collaborative Research Network Writing Group.  “Causes of death among stillbirths.”  JAMA 306(22):2459–2468.  Dec 14, 2011.  512 stillbirths with postmortem, 59 US hospitals, 2006–2008.  Full text read from PMC.  Mirror:  PMC

    1. 9a.

      Section Results:  “umbilical cord abnormalities in 53 (10.4%; 95% CI, 7.9%–13.4%)”. ↩ ↩

    2. 9b.

      Section Results:  “Obstetric complications were the most common category for cause of death (150 cases [29.3%; 95% CI, 25.4%–33.5%]), including abruption (38 cases [7.4%; 95% CI, 5.4%–10.1%])”. ↩

    3. 9c.

      Section Comment:  “Umbilical cord abnormalities accounted for 10% of our possible or probable causes of death, which is considerably higher than in previous studies, 23 , 24 and were more common in stillbirths of greater than 32 weeks’ gestation. Nuchal cords are noted in almost one-fourth of uncomplicated pregnancies. 28 Our criteria for considering a cord abnormality to be a cause of death were rigorous and included vasa previa, cord entrapment, and evidence of occlusion and fetal hypoxia, prolapse, or stricture with thrombi. 18 , 29 Nuchal cord alone was not considered a cause of death.” ↩ ↩ ↩

    4. 9d.

      Section Introduction:  “Stillbirth, Defined As Fetal death at 20 weeks’ gestation or later, is one of the most common adverse pregnancy outcomes in the United States and affects approximately 1 in 160 pregnancies.” ↩

  10. 10.

    Henry, E. et al.  “Neonatal outcomes following a tight nuchal cord.”  Journal of Perinatology 33(3):231–234.  2013.  Read from the PubMed abstract (PMID 22699359);  full text paywalled.  Live births only.

    1. 10a.

      Section Abstract, Study design:  “Nuchal cord was defined as a loop of umbilical cord ≥360° around the fetal neck. 'Tight' was defined as the inability to manually reduce the loop over the fetal head, and 'loose' as the ability to manually reduce the loop over the head.” ↩

    2. 10b.

      Section Abstract, Result:  “Of 219,337 live births in this period, 6.6% had a tight nuchal cord and 21.6% had a loose nuchal cord.” ↩

    3. 10c.

      Section Abstract, Result:  “Term neonates with a tight nuchal cord were slightly more likely to be admitted to a Neonatal Intensive Care Unit (6.6% vs 5.9% admission rate, P=0.000). Those with a tight nuchal cord were not more likely to have dopamine administered or blood hemoglobin measured on the first day, nor were they more likely to receive a transfusion or to die.” ↩ ↩

    4. 10d.

      Section Abstract, Result:  “Owing to the very large number of subjects, several intergroup differences were statistically significant but all were judged as too small for clinical significance.”  Section Abstract, Conclusion:  “No differences in demographics or outcomes, judged as clinically significant, were associated with a tight nuchal cord.” ↩ ↩

  11. 11.

    Masad, Roee et al.  “The effect of nuchal cord on perinatal mortality and long-term offspring morbidity.”  Journal of Perinatology 40(3):439–444.  2020.  Soroka University Medical Center, Israel.  Read from the PubMed abstract;  full text paywalled.

    1. 11a.

      Section Abstract, Results:  “243,682 deliveries were included. Of them, 34,332 (14.1%) were diagnosed with nuchal cord. Perinatal mortality rate was comparable between groups (0.5 vs. 0.6%, p = 0.16).” ↩

    2. 11b.

      Section Abstract, Conclusions:  “Nuchal cord is not associated with higher rate of perinatal mortality nor long-term cardiorespiratory morbidity.” ↩ ↩

  12. 12.

    From Linde 2018 Table 5, term births:  530 deaths in 170,262 entangled births is 0.311%;  1,161 in 639,259 not entangled is 0.182%.  The difference is 0.130 percentage points, or 1.30 per 1,000 entangled births, about 1 in 771.  Entangled births are 170,262 of 809,521 term births, or 21.0%, so the excess across all term births is 0.21 × 1.30 = 0.27 per 1,000.  This treats the whole association as caused by the loop, so it is an upper bound. ↩ ↩ ↩

  13. 13.

    Dresang, Lee T., and Nicole Yonke.  “Management of spontaneous vaginal delivery.”  American Family Physician 92(3):202–208.  Aug 1, 2015.  Read from the PubMed abstract (PMID 26280140).

    1. 13a.

      Section Abstract:  “A tight nuchal cord can be clamped twice and cut before delivery of the shoulders, or the baby may be delivered using a somersault maneuver in which the cord is left nuchal and the distance from the cord to placenta minimized by pushing the head toward the maternal thigh.” ↩ ↩

  14. 14.

    Smith, K. C. et al.  “A survey of equine abortion, stillbirth and neonatal death in the UK from 1988 to 1997.”  Equine Veterinary Journal 35(5):496–501.  Jul 2003.  Animal Health Trust, Newmarket.  Read from the PubMed abstract (PMID 12875329).  Diagnostic submissions, not a population sample.

    1. 14a.

      Section Abstract, Results:  “Problems associated with the umbilical cord, comprising umbilical cord torsion and the long cord/cervical pole ischaemia disorder, were the most common diagnoses (38.8%: 35.7% umbilical cord torsion and 3.1% long cord/cervical pole ischaemia disorder).” ↩ ↩

  15. 16.

    Suzuki, Shunji, and Yukiko Fuse.  “Length of the umbilical cord and perinatal outcomes in Japanese singleton pregnancies delivered at greater than or equal to 34 weeks' gestation.”  Journal of Clinical Gynecology and Obstetrics 1(4–5):57–62.  Oct 23, 2012.  CC BY.  Japanese Red Cross Katsushika Maternity Hospital, Tokyo, 2002–2009.  Publisher site unreachable;  read from the Wayback copy.  Mirror:  Archive.org

    1. 16a.

      Section Results:  “The average of the length of the umbilical cord was 56.2 ± 11.7 cm (range: 19 - 133 cm).” ↩ ↩ ↩

    2. 16b.

      Section Discussion:  “In theory, fetal movement produces a tension on the cord that creates ample free length for delivery plus the length of the wrapped cord [ 3 ] . Although an entangled cord may be at risk for intermittent or partial occlusion of umbilical blood flow as previously reported [ 12 , 13 ] , the excessively long cord may have self-protective effects to protect the fetuses from the risk of decreasing umbilical blood flow.”  Reference 3 is a web page of Pediatric and Perinatal Pathology Associates. ↩

  16. 17.

    Naeye, R. L.  “Umbilical cord length: clinical significance.”  Journal of Pediatrics 107(2):278–281.  Aug 1985.  Read from the PubMed abstract (PMID 4020556).

    1. 17a.

      Section Abstract:  “Umbilical cord length in 35,779 neonates was analyzed to determine values after mid-gestation and to see if abnormal values have clinical significance. Growth slowed after twenty-eighth week of gestation but did not stop before term.” ↩

  17. 18.

    Miller, M. E. et al.  “Short umbilical cord: its origin and relevance.”  Pediatrics 67(5):618–621.  May 1981.  Read from the PubMed abstract (PMID 7254991).

    1. 18a.

      Section Abstract:  “These findings were interpreted as showing that umbilical cord growth occurs in response to tensile forces relating to intrauterine space availability and fetal movement during early development. Thus, the finding of a short umbilical cord may indicate diminished fetal movement from either early intrauterine constraint or fetal limb dysfunction.” ↩ ↩

  18. 19.

    Larson, J. D. et al.  “Multiple nuchal cord entanglements and intrapartum complications.”  American Journal of Obstetrics and Gynecology 173(4):1228–1231.  Oct 1995.  Read from the PubMed abstract (PMID 7485326).  Singleton, vertex, term deliveries in labour, 1990–1994.

    1. 19a.

      Section Abstract, Results:  “Of the 8565 deliveries, the frequency of two or more cord entanglements at delivery was 3.8%.” ↩

    2. 19b.

      Section Abstract, Conclusion:  “A multiple nuchal cord entanglement was associated with a greater risk of meconium, an abnormal fetal heart rate pattern during advanced labor, the need for operative vaginal delivery, and mild umbilical artery acidosis at birth; however, there was no added risk of an adverse neonatal outcome.” ↩

  19. 20.

    Peesay, Morarji.  “Nuchal cord and its implications.”  Maternal Health, Neonatology and Perinatology 3:28.  2017.  CC BY 4.0.  A review;  its figures are secondary.  Mirror:  PMC

    1. 20a.

      Section Biomechanics of umbilical cord, first paragraph:  “Wharton’s Jelly is a porous structure with poroelastic behavior and has proteoglycans and hyalauronic acid. It is supposed to protect against constriction due to fetal grasping, labor contractions, knots, kinks, or loops.” ↩

    2. 20b.

      Section Biomechanics of umbilical cord, second paragraph:  “Umbilical cords have elastic stretch up to 12.5% of its length [ 11 ]. Most cord ruptures happen within 12 in. of the fetus; 22% of the time ruptures occur at the placental end of umbilical cord. … Tensile strength of umbilical cord indicates that the average load required to break the cord is around 10–14 lbs. [ 11 ].”  Reference 11 is Crichton, Tensile strength of the umbilical cord, Am J Obstet Gynecol 1973;  not read. ↩

    3. 20c.

      Section Abstract:  “Nuchal cords are more likely to cause problems when the cord is tightly wrapped around the neck, with effects of a tight nuchal cord conceptually similar to strangulation.”  Section Clinical features:  “Infants with a tight nuchal cord may develop signs and symptoms such as hypovolemia, hypotension, decreased perfusion and mild respiratory distress. Other findings occasionally noted may include facial duskiness”. ↩ ↩

    4. 20d.

      Section Incidence:  “Larson JD et al. [ 3 ] reported that the overall incidence of nuchal cords was 6% at 20 wks GA and 29% at 42 weeks of gestation.”  Reference 3 is Larson 1995, whose abstract describes term deliveries only. ↩

  20. 21.

    From the Stillbirth Collaborative Research Network paper:  stillbirth affects "approximately 1 in 160 pregnancies" in the United States, which is 6.25 per 1,000, and cord abnormalities were a probable or possible cause in 10.4%.  6.25 × 0.104 = 0.65 per 1,000 pregnancies, about 1 in 1,540.  A "possible" cause is counted as a cause here, so this too is an upper bound. ↩ ↩

  21. 22.

    Krakowiak, Paula et al.  “Risk factors and outcomes associated with a short umbilical cord.”  Obstetrics and Gynecology 103(1):119–127.  Jan 2004.  Read from the PubMed abstract (PMID 14704255);  full text paywalled.

    1. 22a.

      Section Abstract, Results:  “A short cord was associated with increased risk for maternal labor and delivery complications, including retained placenta (RR 1.6; 95% CI 1.2, 2.3) and operative vaginal delivery (RR 1.4; 95% CI 1.3, 1.5). Adverse fetal and infant outcomes in cases included fetal distress (RR 1.8; 95% CI 1.6, 2.1) and death within the first year of life among term infants (RR 2.4; 95% CI 1.2, 4.6).” ↩ ↩

    2. 22b.

      Section Abstract, Results:  “Case infants were more likely to be female (OR 1.3; 95% CI 1.2, 1.4), have a congenital malformation (OR 1.6; 95% CI 1.4, 1.8), and be small for their gestational age (risk ratio [RR] 1.6; 95% CI 1.4, 1.9).” ↩

  22. 23.

    From Linde 2018 Tables 3 and 4:  short cords, perinatal death 0.67% against 0.46%, an excess of 2.1 per 1,000 short-cord births;  long cords, 0.83% against 0.44%, an excess of 3.9 per 1,000 long-cord births.  Each tail is about 10% of births by definition. ↩

  23. 24.

    Peregrine, E. et al.  “Ultrasound detection of nuchal cord prior to labor induction and the risk of Cesarean section.”  Ultrasound in Obstetrics and Gynecology 25(2):160–164.  Feb 2005.  Read from the PubMed abstract (PMID 15543520).

    1. 24a.

      Section Abstract, Results:  “A nuchal cord was present at 18% of deliveries. … The sensitivity of ultrasound in diagnosing a nuchal cord was 37.5%, with specificity, positive and negative predictive values of 80%, 29% and 85%, respectively. The presence of a nuchal cord did not significantly increase the risk of delivery by Cesarean section (35% vs. 28%; relative risk = 1.22; 95% CI, 0.80-1.87)”. ↩

  24. 25.

    Mercer, Judith S. et al.  “Nuchal cord management and nurse-midwifery practice.”  Journal of Midwifery and Women's Health 50(5):373–379.  2005.  Read from the PubMed abstract (PMID 16154063).

    1. 25a.

      Section Abstract:  “Evidence for specific management techniques is lacking. Cutting the umbilical cord before birth is an intervention that has been associated with hypovolemia, anemia, shock, hypoxic-ischemic encephalopathy, and cerebral palsy. This article proposes use of the somersault maneuver followed by delayed cord clamping for management of nuchal cord at birth”. ↩

  25. 26.

    Whitwell, K. E.  “Morphology and pathology of the equine umbilical cord.”  Journal of Reproduction and Fertility Supplement (23):599–603.  Oct 1975.  Read from the PubMed abstract (PMID 1060852).

    1. 26a.

      Section Abstract:  “In 95% of normal Thoroughbred foals the cord measures less than 84 cm. Factors which govern cord length are not known. Seven pathological conditions involving the umbilical cord are described. Increased length is the most common abnormality and predisposes to three potentially lethal conditions, strangulation of the cord around the fetus, excessive torsion, and allantochorionic necrosis at the cervical pole.” ↩