Long-term respiratory outcomes in early-term born offspring: a systematic review and meta-analysis

Newborns exhibit the lowest immediate respiratory morbidity rates when born at full term (39-40 completed weeks of gestation). We evaluated whether early-term deliveries (37 0/7 to 38 6/7 weeks of gestation) bear a substantial impact on overall and specific long-term respiratory outcomes of offspring up to the age of 18 years compared with full-term or later deliveries.

We searched PubMed, Medline, Embase, and relevant reference lists from January 2012 to May 2020.

This systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews guidelines and was registered on International Prospective Register of Systematic Reviews. Any observational or randomized human trials addressing the association between early-term delivery and long-term respiratory outcomes in the offspring, restricted to studies published in English, were included. The search included terms relating to gestational age, pediatric morbidity, and respiratory outcomes. We included studies assessing long-term respiratory disease (1-18 years) of offspring born early term compared with offspring born full term and later.

Here, 2 independent reviewers extracted data and assessed the risk of bias. Using a random-effect meta-analysis, pooled relative risk with their 95% confidence intervals and heterogeneity were determined. Publication bias was assessed using funnel plots with Egger regression line and contours, and sensitivity analyses were performed using Baujat plots.

Overall, 14 studies were included after screening nearly 2500 abstracts. These studies included nearly 8 million patients and were subjected to qualitative and quantitative analyses. Early-term delivery significantly increased the risk of total respiratory morbidity in the offspring (relative risk, 1.20; 95% confidence interval, 1.16-1.26) compared with full-term delivery. The increased respiratory morbidity was attributed to obstructive airway diseases (relative risk, 1.19; 95% confidence interval, 1.12-1.27) and infectious respiratory diseases (relative risk, 1.22; 95% confidence interval, 1.17-1.29). Most studies were of acceptable quality.

This comprehensive meta-analysis suggested that early-term delivery poses a risk of long-term pediatric respiratory morbidity compared with full-term delivery. Other factors throughout the years cannot be accounted for. Our study has added an important perspective to be considered when balancing the fetal, maternal, and neonatal risks associated with delivery timing.