Mediation effect of pregnancy-induced hypertension on the association between assisted reproductive technology and adverse neonatal outcomes: a population-based study

Background Assisted reproductive technology (ART) has been widely used in the treatment of infertility, and is associated with adverse maternal and neonatal outcomes. However, the potential pathways by which ART affects adverse neonatal outcomes are unclear. We aimed to investigate the role of pregnancy-induced hypertension (PIH) in the association between ART and adverse neonatal outcomes. Methods Adult women (aged ≥ 18 years) with a singleton pregnancy in the National Vital Statistics System (NVSS) 2020 were enrolled in this retrospective cohort study. Study outcomes were adverse neonatal outcomes, including premature birth, low birth weight, and admission to the neonatal intensive care unit (NICU). Logistic regression models were utilized to investigate the association between ART, PIH, and adverse neonatal outcomes, expressed as odds ratio (OR) and 95% confidence interval (CI). The distribution-of-the-product method was used to explore whether there was a mediating effect of PIH between ART and adverse neonatal outcomes, and the 95% CI of the distribution-of-the-product did not contain 0 indicating a mediating effect. Results This study included 2,824,418 women, of whom 35,020 (1.24%) women used ART, 239,588 (8.48%) women had PIH, and 424,741 (15.04%) neonates had any adverse neonatal outcomes. The use of ART was associated with higher odds of PIH (OR = 1.42; 95%CI: 1.37–1.46) and any adverse neonatal outcomes (OR = 1.47; 95%CI: 1.43–1.51). The distribution-of-the-product was 0.31 (95%CI: 0.28–0.34), and 8.51% of the association between ART and adverse neonatal outcomes was mediated through PIH. Among different adverse neonatal outcomes, PIH mediated 29.17% of the association between ART and low birth weight, 9.37% of the association between ART and premature birth, and 12.20% of the association between ART and NICU admission. The mediating effect of PIH was found in women of different ages (< 35 years and ≥ 35 years) and parities (primipara and multipara). Conclusion This study supports a mediating role for PIH in the association between ART and adverse neonatal outcomes. Further studies are needed to determine the mechanisms by which AR affects PIH so that interventions to reduce PIH can be developed to reduce adverse neonatal outcomes associated with ART.