Abstract
<title>Abstract</title> <p>Background Early childbearing is associated with adverse health outcomes for women and girls, including the risk of intimate partner violence (IPV) and adverse pregnancy outcomes. Most existing research has focused on the direct association between age and adverse birth outcomes, with younger mothers experiencing higher risk. Fewer studies have examined IPV as a potential effect modifier in this relationship. Those who experience early marriage are at higher risk of experiencing intimate partner violence, which may change that relationship. Early marriage is associated with increased risk of IPV, which may influence the association between age at first marriage and adverse pregnancy outcomes. In Kenya, where child marriage remains prevalent, further research is needed to better characterize these relationships. Design and Methods: The study design utilizes the 2022 Kenya Demographic Health Survey (DHS) data set to identify women under 30 and compare women who were partnered ≤ 18 versus ≥ 19. It was identified whether those included were exposed to adverse pregnancy outcomes. The outcome was self-reported adverse pregnancy outcomes. DHS defines union as the time that a woman or girl cohabitates with their partner. Logistic regression was used to assess the association between age at first marriage and adverse pregnancy outcomes, adjusting for IPV, education level, and number of pregnancies. An interaction term between age at first marriage and IPV was included to assess effect modification. Results Women who entered union at age 18 or younger had 68% higher odds of adverse pregnancy outcomes compared to those who entered union at age 19 or older. They also had higher odds of experiencing physical violence (OR ≈ 2.0) and any IPV (approximately 85.7% higher odds) compared to those who entered union later. In models including IPV interaction terms, the association between early union and adverse pregnancy outcomes was attenuated compared to models without IPV, suggesting potential effect modification by IPV exposure. Conclusions Intimate partner violence is independently associated with age at first marriage and adverse pregnancy outcomes and may modify the relationship between age at first marriage and adverse pregnancy outcomes among Kenyan women under 30.</p>