multivitamin versus multivitamin-mineral supplementation and pregnancy outcomes: a single-blind randomized clinical trial

background: increased requirement and decreased dietary intakes of micronutrients during pregnancy might affect maternal health and pregnancy outcomes. this study was aimed to examine the effects of two types of multiple micronutrient supplementations on pregnancy outcomes in kashan, iran. methods: in a randomized single‑blind controlled clinical trial, 104 primigravid singleton pregnant women aged 18‑30 years were randomly assigned to receive either a multivitamin (n = 51) or a multivitamin‑mineral (n = 53) supplements for 20 weeks. participants consumed supplements once a day at week 16 of gestation. maternal anthropometric data as well as newborn’s weight, height, head circumference and 5‑min apgar score were also determined. independent samples t‑test was used for comparing between‑group means. multivariate linear regression analysis was used to identify determinants of newborn’s weight, height and head circumference. results: women taking multivitamin‑mineral supplements gained marginally less weight until week 28 than those taking multivitamin supplements (weight at week 28 of gestation: 67.5 ± 11.4 vs. 71.6 ± 10.3 kg, p = 0.06). mean body mass index at week 28 (25.8 ± 4.0 vs. 28.4 ± 3.7 kg/m2, p = 0.001) as well as at delivery (28.0 ± 3.9 vs. 30.1 ± 3.8 kg/m2, p = 0.006) was lower among women taking multivitamin‑mineral supplements than those taking multivitamin supplements. although no significant difference was seen in newborns’ height and apgar score between the two groups, mean birth weight (3.3 ± 0.4 vs. 3.1 ± 0.4 kg, p = 0.04) and head circumference (35 ± 1.4 vs. 34 ± 1.3 cm, p < 0.0001) of the infants whose mothers receiving multivitamin‑mineral supplements were higher than those whose mothers received multivitamins. multivitamin‑mineral use by pregnant women was a significant predictor of infants’ weight (β =0.191, p = 0.03) and head circumference (β =0.907, p = 0.005). conclusions: in conclusion, we found that birth weight and head circumference was increased in infants whose mothers received multivitamin‑mineral supplements for 5 months during pregnancy compared with infants whose mothers received multivitamin supplements.