This study sought to investigate whether administering 800 international units (IU) of vitamin D3 orally would enhance maternal serum 25-hydroxyvitamin D (25OHD) levels, improve lipid profiles, and affect pregnancy outcomes when compared to a dose of 400 IU in pregnant women dealing with overweight and obesity.

Conducted as a two-arm, parallel, non-blinded randomized controlled trial, the research encompassed 274 pregnant women with a body mass index (BMI) of ≥25 kg/m2 within sixteen weeks of gestation. Volunteers were randomized to receive 800 IU/day (intervention arm) or 400 IU/day (control arm) of oral vitamin D3 supplements. Maternal serum 25OHD and lipid levels at 24-28 weeks of gestation were the key endpoints assessed, while maternal and birth-linked factors were the secondary endpoints ascertained.

The intervention arm (n = 112) displayed substantially raised 25OHD levels at 24-28 weeks compared to controls (n = 119) (adjusted mean difference 6.52 nmol/L; 95% confidence interval [CI] 2.74, 10.31). Moreover, a greater proportion of women in the intervention group attained adequate 25OHD levels when compared to the control group (p < 0.001), as depicted in Table 1:

However, no substantial differences were observed in lipid profiles or maternal/birth outcomes between the two groups.

Though oral vitamin D3 supplementation of 800 IU effectively raised serum 25OHD levels, but it did not influence lipid profiles or pregnancy outcomes.