The association between persistent maternal hypotension and small for gestational age neonates

BACKGROUND: The association between maternal hypotension and poor fetal growth has not been well studied. OBJECTIVE: We hypothesized that the presence of persistent maternal hypotension will reflect a chronic reduction of uteroplacental blood flow, leading to placental hypoperfusion and subsequent poor fetal growth. We aimed to evaluate whether persistent hypotension is associated with the risk of having a small for gestational age neonate. A secondary aim was to evaluate whether transient hypotension is associated with the same risk of having a small for gestational age neonate. STUDY DESIGN: We performed a secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be data, a large prospective cohort study of nulliparous women. The inclusion criteria included delivery of subjects with singleton pregnancies at >= 24 weeks' gestation who had systolic and diastolic blood pressure data at 3 antenatal visits between 6 0/7 and 29 6/7 weeks' gestation. Univariable analyses were performed to evaluate the association among persistent hypotension (systolic blood pressure of <100 mm Hg and or diastolic blood pressure of <60 mm Hg at 3 antenatal visits), transient hypotension (systolic blood pressure <100 mm Hg and diastolic blood pressure <60 mm Hg at any 1 of 3 aforementioned visits but not all 3), maternal characteristics and small for gestational age neonates. Variables found to be significant (P<.05) were included in multivariable logistic regression. RESULTS: Here, 164 of 7233 participants (2.3%) had persistent hypotension. In univariable analyses, subjects with persistent hypotension compared with those without were significantly more likely to have small for gestational age neonates (21.3% vs 11.6%; P<.001). When adjusting for confounders, persistent hypotension remained significantly associated with an increased risk of having a small for gestational age neonate (adjusted odds ratio, 1.65; 95% confidence interval, 1.11-2.44). In multivariable analysis, transient hypotension was not associated with an increased risk of having a small for gestational age neonate. CONCLUSION: Persistent hypotension was significantly associated with small for gestational age among neonates born to low-risk nulliparous women.