Trimester-Based Analysis of Vitamin Supplementation During Pregnancy

Background: Maternal nutritional requirements change with each trimester, making it crucial to provide appropriate vitamin supplementation tailored to each stage. In this study, we investigated the trimester-specific patterns of various vitamin supplements in pregnant women. Methods: In this multicenter cross-sectional study, we analyzed a total of 816 singleton pregnant women who visited hospitals for prenatal care from April 2023 to December 2023. Participants were grouped by trimester, with 140 in the first trimester, 365 in the second, and 311 in the third trimester. A stratified analysis by trimester was performed using multiple linear regression and logistic regression models to examine trimester-specific differences in vitamin supplement intake. A one-way analysis of variance was conducted to compare the total vitamin supplement intake across trimesters. Results: Among the 816 pregnant women, 98.16% (801/816) reported taking at least one supplement, with the mean number of supplements increasing from 2.92 ± 1.27 in the first trimester to 4.04 ± 1.63 in the second and 4.37 ± 1.52 in the third trimester. Notably, iron supplementation increased significantly across trimesters. Stratification analysis revealed that maternal age significantly influenced calcium intake (p-value for interaction = 0.03), with women aged ≥35 years exhibiting higher intake in the third trimester. However, parity and body mass index (BMI) did not show significant interactions with any supplement type. Vitamin D and folic acid intake remained consistently high across trimesters, indicating widespread awareness of their importance. These findings suggest that supplementation practices vary based on pregnancy stage and maternal characteristics. Conclusions: Our study examined the patterns of vitamin supplement intake among pregnant women in Republic of Korea across trimesters. We anticipate that this research will serve as a foundational study, providing valuable insights for future investigations into trimester-specific supplement use among pregnant women.