Fetal growth after preterm premature rupture of membranes: is it related to amniotic fluid volume?

OBJECTIVE

Preterm premature rupture of membranes (PPROM) has been associated with an increased rate of fetal growth restriction (FGR). It is unknown whether impairment of fetal growth is mediated through external compression from decreased amniotic fluid volume or (an)other mechanism(s).

METHODS

Over a three-year period all patients with singleton pregnancies experiencing PPROM at <37 weeks lasting greater than 10 days, and who underwent serial sonograms to assess fetal biometry after PPROM, were included in the study. Patients were excluded for congenital anomalies or other inherent risk factors for abnormal fetal growth. Fetal abdominal circumference (AC) percentiles were compared between the first sonographic exam after PPROM and the last exam before delivery. The median amniotic fluid index between PPROM and delivery was correlated with the change in AC percentiles while controlling for the duration of PPROM. Statistical analysis utilized one-way analysis of variance and correlation; a p value of <0.05 was considered significant.

RESULTS

Twenty-two patients met our inclusion criteria with a mean duration (+/-SD) of PPROM of 58 days (+/-46). The median AFI during the PPROM period was not correlated with the change in AC percentiles after controlling for duration of PPROM (p = 0.49).

CONCLUSIONS

The residual amniotic fluid volume after PPROM does not appear to correlate with fetal growth suggesting that the increased rate of FGR in PPROM is not secondary to oligohydramnios. We hypothesize that the intrauterine pathologic processes responsible for membrane rupture may also interfere with fetal growth.