Vitamin D status and gestational weight gain: A narrative review of maternal and fetal metabolic risk.

内容摘要

Gestational Weight Gain (GWG) affects maternal and fetal health. Vitamin D insufficiency, common during pregnancy, may impact weight control via metabolic, inflammatory, and endocrine pathways. However, the association between maternal vitamin D and GWG remain unclear. Therefore, this narrative review's objective is to integrate existing evidence on the correlations between maternal vitamin D and GWG, examine the effect of pre-pregnancy Body Mass Index (BMI), assess the cumulative effects of vitamin D deficiency and inadequate GWG on pregnancy outcomes, and assess the efficacy of vitamin D supplementation. A narrative review was conducted in accordance with SANRA 2.0 principles, with the search strategy reported in line with PRISMA-S guidance. A literature review was conducted in PubMed, Scopus, and Google Scholar to identify studies examining gestational weight gain (GWG) and serum 25-hydroxyvitamin D status published between January 2015 and November 2025. Observational and interventional studies were eligible for inclusion. After eliminating duplicates, reviewers independently evaluated 1,395 records; 14 studies were included. The prevalence of vitamin D deficiency and its bidirectional associations with maternal weight, gestational weight gain as a modifier of vitamin D's metabolic effects, combined effects on fetal and offspring outcomes, and supplementation trial evidence were narratively synthesized. Vitamin D insufficiency affected 30-85% of pregnant women worldwide. Bidirectional vitamin D-GWG relationships differed among studies, with prepregnancy BMI as a substantial effect modifier. In overweight women, low first trimester vitamin D levels were associated with 3.70 kg higher total GWG. Vitamin D's insulin resistance protection was greatly reduced by excessive GWG. High-dose supplementation (1600 IU/day) met biochemical needs but did not affect GWG. In one cohort, both low vitamin D and suboptimal GWG independently predicted small-for-gestational-age births. The association between maternal vitamin D status and gestational weight gain remains inconsistent across the current evidence base. Pre-pregnancy BMI may modify this relationship, with the strongest associations observed among overweight and obese women. Integrated strategies addressing both vitamin D adequacy and appropriate gestational weight gain, particularly among women with elevated pre-pregnancy BMI, should be explored in future research. Vitamin D supports skeletal health and also contributes to immune and metabolic function. In pregnancy, achieving recommended gestational weight gain is important because both inadequate and excessive gain are linked to adverse outcomes for mothers and infants. This narrative review summarises global evidence on whether maternal vitamin D status is associated with gestational weight gain and whether pre-pregnancy body weight influences this relationship. We searched major bibliographic databases for studies published between 2015 and 2025 that measured vitamin D during pregnancy and reported gestational weight gain. Across studies, results were inconsistent. Some reported associations between lower vitamin D status and higher or lower gestational weight gain, while others found no clear relationship. Methodological differences likely explain part of this variability, including timing of vitamin D assessment, definitions of deficiency, measurement of weight gain, and adjustment for key factors such as pre-pregnancy body mass index, season, diet, physical activity, and supplementation. Although evidence remains mixed, higher pre-pregnancy adiposity is frequently associated with lower circulating vitamin D and may also relate to a greater likelihood of non-recommended gestational weight gain and metabolic complications. These overlapping risks highlight the importance of considering baseline maternal weight status when interpreting the vitamin D and gestational weight gain literature. Overall, current evidence does not establish a consistent causal link between vitamin D status and gestational weight gain. Robust prospective studies and adequately powered trials are needed to clarify directionality and determine whether optimising vitamin D status, within comprehensive antenatal care, supports healthier gestational weight trajectories.