Meconium stained amniotic fluid exposure and long-term respiratory morbidity in the offspring.

Objective: Meconium stained amniotic fluid (MSAF) is a well-established risk factor for neonatal short-term respiratory complications. Little is known regarding the long-term morbidity. We investigated the possible association between MSAF and offspring respiratory morbidity.

Methods: A population-based, cohort study of singleton deliveries occurring between 1991 and 2014 at a sole regional tertiary medical center was performed. Incidence of offspring respiratory related hospitalizations up to the age of 18 years were evaluated and compared to unexposed offspring. A Kaplan-Meier survival curve was used to compare cumulative respiratory morbidity incidence, and a Cox proportional hazards model was used to control for confounders.

Results: During the study period 242,342 deliveries met the inclusion criteria. Of them, 14.7% (n = 35,609) were complicated with MSAF. Incidence of respiratory-related hospitalizations was significantly lower in children exposed to MSAF as compared to the unexposed group (4.5% vs. 4.9%, respectively; p < .01). Specifically, hospitalizations involving pneumonitis were significantly less common among the MSAF group (odds ratio, 0.35; 95% confidence interval [95% CI], 0.13-0.96; p = .03). The Kaplan-Meier survival curve demonstrated significantly lower total cumulative respiratory morbidity rates in the MSAF exposed group (log rank p < .01). In the Cox model, controlled for clinically relevant confounders, MSAF exhibited an independent and significant protective effect on long-term childhood respiratory morbidity (aHR, 0.91; 95% CI, 0.86-0.96; p < .01).

Conclusions: Fetal exposure to MSAF during labor appears to be associated with lower rates of long-term respiratory related hospitalizations in the offspring. Changes in offspring microbiome, as well as functional and anatomical modulations possibly resulting from MSAF exposure, might offer a plausible explanation of our findings.