Maternal multimorbidity, lifestyle behaviours during pregnancy, and early-childhood growth trajectories: a register-based cohort study

<h2>Summary</h2><h3>Background</h3> The burden of chronic conditions is increasing in women during pregnancy, but maternal multimorbidity and associated long-term effects on children have not been well-studied. This study examines the associations of maternal multimorbidity and lifestyle behaviours with growth trajectories in children. <h3>Methods</h3> This longitudinal study used data of women who gave live birth between July 2020 and June 2021 in Huai'an, China. Information of 15 maternal long-term conditions were extracted from electronic maternity information system, and multimorbidity was defined as presence of two or more maternal conditions. Maternal lifestyle score was constructed based on physical activity, sleep duration and quality, regularity of daily meals, and dietary preference collected at the second trimester of pregnancy. Children's body mass index (BMI) was measured ten times, from birth to 36 months. Latent class growth mixed model was conducted to identify growth trajectories in children using age- and sex-specific BMI <i>z</i>-scores. Adjusted multinomial logistic regression models were used to assess the associations. <h3>Findings</h3> Among 22,440 mother–child pairs, 1288 (5.7%) mothers were screened for multimorbidity during pregnancy. Five growth trajectories were identified during children early-childhood. Children born to mothers with multimorbidity had 79% increased relative risks of experiencing low birth weight with accelerated BMI gain (relative risk ratio [RRR] = 1.79, 95% confidence interval [CI] = 1.39–2.31). The significantly rapid rate of BMI gain among these children occurred within the first eight months. Certain multimorbidity patterns were particularly associated with a higher relative risk of this growth trajectory, for example, the Cardiometabolic pattern (RRR = 2.63, 95% CI=2.03–3.40) and the Hepatic-haematological pattern (RRR = 1.79, 95% CI=1.18–2.71) were associated with a higher relative risk of offspring experiencing low birth weight with accelerate BMI gain. Among 7061 mothers who reported their lifestyle behaviours during pregnancy, 14.6% had unfavourable lifestyles. Children born to mothers with multimorbidity and unfavourable lifestyles were associated with 4.13-fold (1.65–10.3) increased relative risk of low birth weight with accelerated BMI gain. <h3>Interpretation</h3> Maternal multimorbidity and unfavourable lifestyles during pregnancy are associated with higher risks of children experiencing low birth weight with accelerated BMI gain. The provision of high quality comprehensive integrated antenatal care with healthy lifestyle education and interventions are required for all women and especially for women with multimorbidity, to improve their health and wellbeing during pregnancy and to contribute to health benefits for their infants. <h3>Funding</h3> China Medical Board (21-416), Natural Science Foundation of China (72474197), Zhejiang University Fundamental Research Fund for the Central Universities, Huai'an Science and Technology Program (HAB2024039), Key Medical Program of Jiangsu Health Commission (ZD2021044).