Abstract
ObjectivesTo determine risk factors for short and long umbilical cord, entanglement and knot. Explore their associated risks of adverse maternal and perinatal outcome, including risk of recurrence in a subsequent pregnancy. To provide population based gestational age and sex and parity specific reference ranges for cord length.DesignPopulation based registry study.SettingMedical Birth Registry of Norway 1999–2013.PopulationAll singleton births (gestational age>22weeks<45 weeks) (n = 856 300).MethodsDescriptive statistics and odds ratios of risk factors for extreme cord length and adverse outcomes based on logistic regression adjusted for confounders.Main outcome measuresShort or long cord (<10th or >90th percentile), cord knot and entanglement, adverse pregnancy outcomes including perinatal and intrauterine death.ResultsIncreasing parity, maternal height and body mass index, and diabetes were associated with increased risk of a long cord. Large placental and birth weight, and fetal male sex were factors for a long cord, which again was associated with a doubled risk of intrauterine and perinatal death, and increased risk of adverse neonatal outcome. Anomalous cord insertion, female sex, and a small placenta were associated with a short cord, which was associated with increased risk of fetal malformations, placental complications, caesarean delivery, non-cephalic presentation, perinatal and intrauterine death. At term, cord knot was associated with a quadrupled risk of perinatal death. The combination of a cord knot and entanglement had a more than additive effect to the association to perinatal death. There was a more than doubled risk of recurrence of a long or short cord, knot and entanglement in a subsequent pregnancy of the same woman.ConclusionCord length is influenced both by maternal and fetal factors, and there is increased risk of recurrence. Extreme cord length, entanglement and cord knot are associated with increased risk of adverse outcomes including perinatal death. We provide population based reference ranges for umbilical cord length.
Highlights
IntroductionIt has been estimated that about 10% of intrauterine deaths in the USA may be attributable to umbilical cord complications, and these complications are associated with clinically significant placental pathology [1]
A normal umbilical cord is of obvious importance for a normal fetal development
The risk of a cord knot was increased in polyhydramnios, and adding a long cord to the model significantly reduced the effect of polyhydramnios
Summary
It has been estimated that about 10% of intrauterine deaths in the USA may be attributable to umbilical cord complications, and these complications are associated with clinically significant placental pathology [1]. In case studies excessive long cords have been associated with cord entanglements, emergency deliveries and fetal thrombotic vasculopathy in the placenta, fetal death and increased risk of neurological complications [5,6]. A short cord has been associated with increased risk of fetal malformations, fetal distress and possibly placental abruption [7,8,9]. The aims of the present study was 1: to determine risk factors for long and short umbilical cord, cord knots and entanglements, 2: to study the associated risks of adverse outcome of pregnancies with abnormal cord length, cord knot and entanglement in the Norwegian population, 3: to study the risk of recurrence of abnormal cord length, cord knot and entanglement in a subsequent pregnancy of the same woman, and 4: to provide population based gestational age, sex and parity specific charts for umbilical cord length
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