Objective: To assess the association between the birth weight of newborns and microbial invasion of the amniotic cavity (MIAC) and/or intra-amniotic inflammation in pregnancies with preterm prelabor rupture of membranes.
Methods: A total of 528 pregnancies with preterm prelabor rupture of membranes were included in this retrospective cohort study. Transabdominal amniocentesis to determine the presence of MIAC (through culturing and molecular biology methods) and intra-amniotic inflammation (according to amniotic fluid interleukin-6 level) was performed as part of standard clinical management. Based on the presence of MIAC and/or intra-amniotic inflammation, the participants were divided into four subgroups: with intra-amniotic infection (presence of both), with sterile IAI (intra-amniotic inflammation alone), with colonization (MIAC alone), and with negative amniotic fluid (absence of both). Birth weights of newborns are expressed as percentiles derived from INTERGROWTH-21st standards for (i) newborn birth weight and (ii) estimated fetal weight.
Results: No differences in birth weights, expressed as percentiles derived from newborn weight standards (infection: median 52; sterile: median 54; colonization: median 50; negative amniotic fluid: median 51; p = .93) and estimated fetal weight standards (infection: median 47; sterile: median 51; colonization: median 47; negative amniotic fluid: median 53; p = .48) were found among the four subgroups. No differences in percentiles (derived from both standards) were found in the subset of participants who delivered within 72 h after rupture of membranes (newborn weight standard, p = .99; estimated fetal weight standard, p = .81).
Conclusions: No association was identified between the birth weight of newborns and the presence of intra-amniotic inflammatory and infection-related complications in pregnancies with preterm prelabor rupture of membranes.
Keywords: Amniocentesis; INTERGROWTH; amniotic fluid; estimated fetal weight; intra-amniotic inflammation; microbial invasion of the amniotic cavity; preterm birth.