Decreased amniotic fluid volume at < 32 weeks of gestation is associated with decreased fetal movements

Abstract

The objective of this study was to assess the relationship between amniotic fluid volume (AFV) and fetal movements at < 32 weeks gestation as assessed by routine biophysical profile (BPP). From a database of 465 consecutive nonhypertensive, nondiabetic patients delivering at < 32 weeks gestation, patients with singleton, nonanomalous fetuses with AFV and fetal movements determined as part of a BPP assessment within 24 hours of delivery were studied. Amniotic fluid volume was scored 0 to 2, according to the following criteria: largest pocket in vertical diameter < 1 cm = 0; < 2 but > 1 cm = 1; > or = 2 cm = 2. Fetal movements (FM) were scored over 30 minutes: 0 if absent, 1 if 1 to 2 movements, 2 if > or = 3 gross (limb/trunk) movements. Variables assessed included fetal presentation, gestational age (GA), premature rupture of membranes (PROM) as a principal indication for delivery, clinical chorioamnionitis (diagnosed by previously published criteria), histologic parameters of infection (in amnion and umbilical cord assessed by a single pathologist blinded to clinical data), and neonatal outcome. Statistical analyses included contingency tables and analysis of variance with p < 0.05 considered significant. Three hundred and fifty-two patients met the inclusion criteria. One hundred and sixty-seven patients (47%) had PROM as a primary indication for delivery. Infrequently, decreased fetal well-being manifested by a BPP < 7 of 10 points was an indication for delivery despite prematurity (n = 7). Of the 352 patients, 80 (23%) had AFV = 0, 60 (17%) had AFV = 1, and 212 (60%) had AFV = 2; and 12 (3%) had FM = 0, 30 (9%) FM = 1, and 310 (88%) FM = 2. There was a significant correlation between decreased AFV and decreased fetal movements (p < 0.0001). Fetal presentation and GA were not significantly different between patients based on score of fetal movements. The incidence of clinical chorioamnionitis was significantly greater in patients with FM = 0 (p < 0.005). We conclude that decreased AFV is associated with decreased fetal movements irrespective of fetal presentation or gestational age. Neonatal outcome (umbilical vasculitis, sepsis, intraventricular hemorrhage) is affected only in unusual cases in which otherwise uncompromised (nonhypoxic, nonacidotic) fetuses have low scores on both these antepartum ultrasonographic parameters.