The Effect of Intermittent Antenatal Iron Supplementation on Maternal and Infant Outcomes in Rural Viet Nam: A Cluster Randomised Trial

Cluster randomized trial in 104 rural communes in Ha Nam Province, Viet Nam, enrolling pregnant women before 16 weeks gestation between 28 September 2010 and 5 November 2010. Active-arm enrollment was 425 participants in twice-weekly IFA and 407 in twice-weekly MMN; women were age >16 years, lived in trial communes, and severe anemia at enrollment was excluded (Hb < 80 g/l). Participants were followed through 6 months postpartum.

Pregnant women received oral twice-weekly supplementation from enrollment until 3 months postpartum. The twice-weekly IFA arm provided 60 mg elemental iron plus 1.5 mg folic acid per capsule, taken as two capsules per week; the twice-weekly MMN arm used the same iron and folic acid dose plus UNIMMAP-containing multiple micronutrients, also two capsules per week. Both active regimens were compared with daily iron-folic acid supplementation.

Twice-weekly antenatal supplementation did not produce a clinically important improvement in birth weight or infant growth compared with daily iron-folic acid. In the twice-weekly IFA arm, mean birth weight was 3,178 [376] g and infants had a higher cognitive composite score at 6 months versus daily IFA (MD 1.89, 95% CI 0.23 to 3.56). The twice-weekly MMN arm also showed no clear advantage for birth weight, head circumference, or length-for-age z-score at 6 months, and infant cognitive scores were not clearly different from daily IFA. Overall, the findings support intermittent antenatal iron-folic acid in this low-iron-deficiency setting, while intermittent multiple micronutrients showed no clear additional benefit.

The trial was conducted in a single rural Vietnamese setting, which limits generalizability. Baseline anemia prevalence was low overall (12.6%), so the study may have had limited ability to show benefit in a population with relatively modest iron deficiency burden. Some outcome reporting was incomplete or imprecise in the extracted data, and the cluster design adds complexity to interpretation.