Perinatal outcomes after intrauterine growth restriction and intermittently elevated umbilical artery Doppler

Abstract

Background: Intermittently elevated umbilical artery pulsatility index has been identified among pregnancies with intrauterine growth restriction but has unclear clinical significance.

Objective: The purpose of this study was to analyze perinatal morbidity and stillbirth after intrauterine growth restriction with an intermittently elevated umbilical artery pulsatility index.

Study design: This retrospective cohort study included nonanomalous singleton, intrauterine growth-restricted pregnancies that received umbilical artery pulsatility index testing at a tertiary-care prenatal diagnostic center from 2010-2016. Women with persistently elevated umbilical artery pulsatility index, absent or reversed end-diastolic blood flow on umbilical artery pulsatility index, or only 1 umbilical artery pulsatility index result were excluded. Intermittently elevated umbilical artery pulsatility index was defined as ≥1 elevated umbilical artery pulsatility index (>95%) and ≥1 normal umbilical artery pulsatility index (≤95%). Women with an intermittently elevated umbilical artery pulsatility index were matched 1:3 by gestational age at intrauterine growth restriction diagnosis to those with a normal umbilical artery pulsatility index. The primary outcome was composite neonatal morbidity and deaths (stillbirth, mechanical ventilation, sepsis, intraventricular hemorrhage, and necrotizing enterocolitis). Secondary outcomes included 5-minute Apgar score, umbilical artery pH, delivery type, and interval from intrauterine growth restriction diagnosis to delivery. We compared outcomes after intermittently elevated umbilical artery pulsatility index with those after normal umbilical artery pulsatility index with multivariable logistic regression, adjusting for gestational age at delivery, betamethasone use, and maternal factors.

Results: Of 1893 women, 143 (7.6%) had an intermittently elevated umbilical artery pulsatility index and were matched to 429 control subjects. Among the 143 women with an intermittently elevated umbilical artery pulsatility index, 78 (54.5%), 52 (36.4%), and 13 (0.9%) women had elevated umbilical artery pulsatility index for 1-24%, 25-49%, and 50-74% of recorded Doppler measurements, respectively. None of the women had an elevated umbilical artery pulsatility index for 75-99% of recorded umbilical artery pulsatility index measurements. The last recorded umbilical artery pulsatility index was elevated for 37 women with an intermittently elevated umbilical artery pulsatility index (25.9%). Overall, the odds of composite neonatal morbidity was similar among intrauterine growth-restricted pregnancies with an intermittently elevated vs a normal umbilical artery pulsatility index (adjusted odds ratio, 1.05; 95% confidence interval, 0.59-1.87); there were no stillbirths. There was no difference in 5-minute Apgar scores, umbilical artery pH, rate of cesarean delivery for fetal distress, or interval from intrauterine growth restriction diagnosis to delivery between the 2 groups. Similarly, sensitivity analyses that stratified the population of intermittently elevated umbilical artery pulsatility index by the proportion of elevated umbilical artery pulsatility index to overall umbilical artery pulsatility index measurements and by whether the last umbilical artery pulsatility index recorded was normal or elevated showed no difference in neonatal morbidity or obstetric outcomes between the comparator groups.

Conclusion: Among intrauterine growth-restricted pregnancies, an intermittently elevated umbilical artery pulsatility index is neither uncommon nor associated with an increased risk of neonatal morbidity, stillbirth, or cesarean delivery. These findings suggest intrauterine growth-restricted pregnancies with intermittently elevated umbilical artery pulsatility index could be managed clinically as are those with normal umbilical artery pulsatility index.

Keywords: elevated umbilical artery pulsatility index; intrauterine growth restriction; neonatal morbidity; normal umbilical artery pulsatility index; stillbirth.