Prenatal diagnosis of a lean umbilical cord: a simple marker for the fetusat risk of being small for gestational age at birth

Objective The purpose of this study was to investigate whether the prenatal diagnosis of a 'lean' umbilical cord in otherwise normal fetuses identifie s fetuses at risk of being small for gestational age (SGA) at birth and of having distress in labor. The umbilical cord was defined as lean when its c ross-sectional area on ultrasound examination was below the 10th centile fo r gestational age. Method Pregnant women undergoing routine sonographic examination were inclu ded in the study. Inclusion criteria were gestational age greater than 20 w eeks, intact membranes, and singleton gestation. The sonographic cross-sect ional area of the umbilical cord was measured in a plane adjacent to the in sertion into the fetal abdomen. Umbilical artery Doppler waveforms were rec orded during fetal apnea and fetal anthropometric parameters were measured. Results During the study Period 860 patients met the inclusion criteria, of whom 3.6% delivered a SGA infant. The proportion of SGA infants was higher among fetuses who had a lean umbilical cord on ultrasound examination than among those with a normal umbilical cord (11.5% vs. 2.6%, p < 0.05). Fetus es with a lean cord had a risk 4.4-fold higher of being SGA at birth than t hose with a normal umbilical cord. After 25 weeks of gestation, this risk w as 12.4 times higher when the umbilical cord was lean than when it was of n ormal size. The proportion of fetuses with meconium-stained amniotic fluid at delivery was higher among fetuses with a lean cord than among those with a normal umbilical cord (14.6% vs. 3.1%, p < 0.001). The proportion of inf ants who had a 5-min Apgar score < 7 was higher among those who had a lean cord than among those with normal umbilical cord (5.2% vs. 1.3%, p < 0.05). Considering only Patients admitted in labor with intact membranes and who delivered an appropriate-for-gestational-age infant, the proportion of fetu ses who had oligohydramnios at the time of delivery was higher among those who had a lean cord than among those with a normal umbilical cord (17.6% ve rsus 1.3%, p < 0.01). Conclusion We conclude that fetuses with a lean umbilical cord have an incr eased risk of being small for gestational age at birth and of having signs of distress at the time of delivery.