Antenatal Vitamin D3 Supplementation in Bangladesh: Randomized Controlled Trial

The primary aims of this study are:

AIM #1 - To assess the effect of weekly antenatal administration of oral vitamin D3 (875 mcg/week = 35,000 IU week ≈ 5,000 IU per day) started in the third trimester (26-29 weeks gestation) on maternal vitamin D status and fetal-neonatal vitamin D status (cord blood), in comparison to a placebo control supplement.

AIM #2 - To demonstrate the maternal and fetal safety of weekly maternal antenatal (second and third-trimester) vitamin D supplementation at a dose of 875 mcg/week by monitoring maternal serum calcium, urinary calcium excretion, cord blood calcium concentration, and newborn clinical parameters.

AIM #3 - To measure the effect of antenatal vitamin D supplementation on selected biomarkers of fetal-neonatal immune function in cord blood: in vitro stimulated cord blood mononuclear cell (CBMC) LL-37 expression, gene expression related to inflammatory and immunoregulatory pathways, Th1/Th2 cytokine secretion, and bactericidal properties.

Inclusion criteria

• Women aged 18 to <35 years.
• Current residence in Dhaka at a fixed address
• Plans to have the delivery performed at the Shimantik maternity center, and to stay in Dhaka throughout the pregnancy and for at least one month past the date of delivery.
• Gestational age of 26th to 29th (inclusive), estimated based on the first day of the last menstrual period (LMP).

Exclusion criteria

• Use of any dietary supplement containing more than 400 IU/day (10 mcg/day) of vitamin D within the month prior to enrolment, or refusal to stop taking supplemental vitamin D at any dose after enrollment.
• Current use of anti-convulsant or anti-mycobacterial (tuberculosis) medications.
• Severe anemia (hemoglobin concentration < 70 g/L).
• Complicated medical or obstetric history that may increase the risk of preterm birth or labor/delivery complications, based on self-report or clinical assessment by physician (e.g., cardiovascular disease, uterine hemorrhage, placenta previa, threatened abortion, hypertension, preeclampsia, preterm labor, or multiple gestation).
• Prior history of delivery of an infant with a major congenital anomaly, birth asphyxia, or perinatal death (stillbirth or death within first week of life).