Background: Whether hypertensive disorders in pregnancy (HDP) are the risk factors of bronchopulmonary dysplasia (BPD) is controversial. A systematic review was made to determine the association between HDP and BPD in preterm infants.
Methods: We searched PubMed, Embase, Cochrane Library, ScienceDirect, Web of Science, with no language limitation, and reviewed the reference lists of the selected articles to identify additional relevant publications and contacted the authors of relevant studies for further information. The data were extracted independently by 2 reviewers who used a predetermined data extraction form. Studies were combined with an odds ratio (OR) using a random-effects model. Meta-regression and subgroup analysis were used to explore potential confounders. Funnel plots, Egger's test and Begg's test were used to investigate the publication bias. The Trim and Fill method was used to control the publication bias.
Results: A total of 787 studies were identified and only 15 studies (20 779 patients) were included. The pooled unadjusted OR showed that HDP was significantly associated with BPD (P=0.04; OR=1.29, 95% CI=1.01-1.65). Heterogeneity was substantial (I(2)=74%) and might be partially explained by different variables in maternal complications between the control groups across the studies. The pooled adjusted OR suggested the same conclusion that HDP was a risk factor for BPD (P=0.01; OR=1.59, 95% CI=1.11-2.26). Funnel plot and Egger's test showed that there were publication bias of unadjusted estimate of association between HDP and BPD.
Conclusions: Unadjusted analyses showed that the rate of BPD was slightly higher in the infants exposed to HDP, and adjusted analyses confirmed this finding. But this result should be interpreted cautiously because substantial heterogeneity and publication bias were identified in this review.