Amniotic fluid index values after preterm premature rupture of the membranes and subsequent perinatal infection.

OBJECTIVE: Our purpose was to determine whether an amniotic fluid index (AFI) <5 cm after preterm premature rupture of the membranes is associated with an increased risk of perinatal infection.

STUDY DESIGN: We performed a nonconcurrent prospective analysis of 225 singleton pregnancies complicated by preterm premature rupture of the membranes, with delivery between 24 and 32 weeks' gestation. All included patients received 2 doses of betamethasone antenatally, in the first 24 hours after admission, and broad-spectrum antibiotic prophylaxis. Patients were categorized into 2 groups on the basis of a 4-quadrant AFI <5 cm (n = 131) or > or =5 cm (n = 94). Perinatal outcomes analyzed included latency until delivery, mode of delivery, and frequencies of clinical chorioamnionitis, postpartum endometritis, and culture-proved early neonatal sepsis. Continuous data were evaluated for normal distribution and tested for significance with the Student t test. Categoric data were tested with the chi(2) and Fisher exact tests. Multiple logistic regression analyses were performed with chorioamnionitis, endometritis, and early-onset neonatal sepsis each as the dependent variable in separate analyses. All 2-sided P values <.05 were considered significant.

RESULTS: Both groups were similar with respect to selected demographics, gestational age at rupture of the membranes, birth weight, and maternal group B streptococcal colonization. Patients with an AFI <5 cm demonstrated a shorter mean latency until delivery (5.5 +/- 4.0 vs 14.1 +/- 5.2) (mean +/- SD) days (P =.02), greater frequency of amnioinfusion therapy (23.6% vs 5.3%) (P <.001), and cesarean delivery for nonreassuring fetal testing (18.3% vs 4. 3%) (P =.01). Multiple logistic regression analysis showed that an AFI <5 cm was the only significant risk factor independently associated with early-onset neonatal sepsis (P =.004) and chorioamnionitis (P =.024).

CONCLUSIONS: An AFI <5 cm after preterm premature rupture of the membranes between 24 and 32 weeks' gestation is associated with an increased risk of perinatal infection and a shorter latency preceding delivery.