Systematic review and meta-analysis regarding maternal apelin in pregnant women with and without preeclampsia.

Aims: To investigate maternal circulating apelin levels in pregnancies with and without preeclampsia.Design and Method: Systematic review and meta-analysis of observational studies reporting circulating apelin in women who develop preeclampsia. We searched databases for appropriate studies published through December 2021, without language restriction. The quality of studies was evaluated using the Newcastle-Ottawa-Scale. Data were pooled as mean difference (MDs) or standardized MDs (SMDs) and 95% confidence interval (95% CI). A random-effects model enabled reporting of differences between groups, minimizing the effects of uncertainty associated with inter-study variability on the effects of different endpoints.Results: We identified a total of 122 studies, and ten of them reported circulating apelin in women with and without preeclampsia. Maternal apelin did not show a difference in preeclamptic compared to normotensive women (SMD: -0.38, 95%CI -0.91 to 0.15), although there was high heterogeneity between the included studies (I2 = 95%). Participants with preeclampsia had higher body mass index, lower gestational age at delivery, and birth weight. Preeclamptic pregnant women with higher BMI showed significantly lower apelin levels in the subgroup analysis. There was no significant apelin difference in the preeclampsia severity sub-analysis.Conclusion: There was no significant difference in apelin levels in pregnant women with and without preeclampsia.