TOPLINE

In pregnancies complicated by preterm prelabor rupture of membranes (PROM), intra-amniotic infection was associated with higher odds of early-onset neonatal sepsis and serious composite adverse perinatal outcomes than other intra-amniotic categories combined, whereas among cases with microbial invasion of the amniotic cavity, bacteria other than Ureaplasma species were associated with worse perinatal and neonatal outcomes than Ureaplasma species alone or in combination with other bacteria.

METHODOLOGY

• Researchers aimed to characterize the intra-amniotic categories of preterm PROM by determining their gestational age-dependent prevalence, amniotic fluid microbial profiles, and short-term perinatal and neonatal outcomes.
• The analysis included 961 women with singleton pregnancies complicated by preterm PROM between 23 + 0 and 36 + 6 weeks' gestation who had at least 2 hours between membrane rupture and the onset of regular uterine activity, delivered at least 24 + 0 weeks' gestation, had a viable fetus at admission, and underwent successful transabdominal amniocentesis from 2012 to 2022.
• Participants were classified into four intra-amniotic categories based on the presence or absence of intra-amniotic inflammation and microbial invasion of the amniotic cavity — intra-amniotic infection (n = 158; median maternal age, 31 years), sterile intra-amniotic inflammation (n = 70; median maternal age, 30 years), microbial invasion of the amniotic cavity without inflammation (n = 106; median maternal age, 30 years), and negative amniotic fluid for inflammation and microorganisms (n = 627; median maternal age, 31 years).
• Intra-amniotic inflammation was assessed by measuring the native amniotic fluid interleukin-6 (IL-6) levels, defined as elevated IL-6 levels at or above the platform-specific thresholds.
• Microbial invasion of the amniotic cavity was evaluated by conducting a microbiologic analysis of the amniotic fluid using culture and molecular methods, defined as the detection of microorganisms and/or their nucleic acids in the amniotic fluid.

TAKEAWAY

• The prevalence of intra-amniotic infection declined from 50%-58% at 23-25 weeks' gestation to 6% by 36 weeks and that of sterile intra-amniotic inflammation fell from 43% at 23-24 weeks' gestation to 4% by 34-36 weeks. In contrast, the prevalence of negative amniotic fluid for inflammation and microorganisms rose from 7% at 23-24 weeks' gestation to 75%-77% by 34-36 weeks; microbial invasion of the amniotic cavity without inflammation was first observed at 29 weeks' gestation and remained relatively stable at 9%-15% at 30-36 weeks.
• A total of 64 microbial species were identified in the amniotic fluid, with Ureaplasma species accounting for 64.4% of all microbial detections.
• Intra-amniotic infection vs the other three categories combined was associated with higher odds of early-onset neonatal sepsis (adjusted odds ratio [aOR], 3.4) and serious composite adverse perinatal outcomes (aOR, 2.0; P < .05 for both).
• Among pregnancies with microbial invasion, bacteria other than Ureaplasma species vs Ureaplasma species detected alone or in combination with other bacteria were associated with higher odds of early-onset neonatal sepsis (aOR, 5.9), culture-proven early-onset neonatal sepsis (aOR, 6.1), intraventricular hemorrhage grades I-II (aOR, 2.4), composite adverse perinatal outcomes (aOR, 2.9), and serious composite adverse perinatal outcomes (aOR, 3.4; P < .05 for all).

IN PRACTICE

"Our findings suggest that characterization of the intra-amniotic environment to identify intra-amniotic categories may provide clinically relevant information for the individualized management of preterm PROM," the authors wrote.

SOURCE

The study was led by Marian Kacerovsky, MD, PhD, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic. It was published online on August 31, 2026, in the American Journal of Obstetrics and Gynecology.

LIMITATIONS

As residual indication bias and treatment-related confounding could not be ruled out, the findings reflected associations rather than cause-and-effect relationships. The long study period might have introduced changes over time that influenced the results. The study was conducted at a single center in a White population, which might limit generalizability of the findings to other settings and populations.

DISCLOSURES

The study was supported by the University Hospital Hradec Kralove through The Biomedical Indicators for Personalized Medicine project co-funded by the European Union. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.