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 (AF I) <5 cm after preterm premature rupture of the membranes is associated wit h an increased risk of perinatal infection. STUDY DESIGN: We performed a nonconcurrent prospective analysis of 225 sing leton pregnancies complicated by preterm premature rupture of the membranes , with delivery between 24 and 32 weeks' gestation. All included patients r eceived 2 doses of betamethasone antenatally, in the first 24 hours after a dmission, and broad-spectrum antibiotic prophylaxis. Patients were categori zed into 2 groups on the basis of a 4-quadrant AFI <5 cm (n = 131) or great er than or equal to 5 cm (n = 94). Perinatal outcomes analyzed included lat ency until delivery, mode of delivery, and frequencies of clinical chorioam nionitis, postpartum endometritis, and culture-proved early neonatal sepsis . Continuous data were evaluated for normal distribution and tested for sig nificance with the Student t test. Categoric data were tested with the chi( 2) and Fisher exact tests. Multiple logistic regression analyses were perfo rmed with chorioamnionitis, endometritis, and early-onset neonatal sepsis e ach 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, ge stational age at rupture of the membranes, birth weight, and maternal group B streptococcal colonization. Patients with an AFI <5 cm demonstrated a sh orter mean latency until delivery (5.5 +/- 4.0 vs 14.1 +/- 5.2) (mean +/- S D) 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 A FI <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.