In the largest programmatic evaluation of antenatal micronutrient supplementation strategies and birth outcomes to date, this study estimated the comparative effectiveness of four antenatal supplementation strategies on adverse birth outcomes in 96 341 women (22·5% of whom had HIV) who presented to antenatal care before 24 weeks gestation in Botswana. The results showed that women who initiated iron-folic acid supplementation (IFAS) had lower risks of most adverse birth outcomes compared with women who initiated iron-only or folic acid-only supplementation, and differences were greatest in women with HIV and women aged 35 years or older. Women who initiated multiple micronutrient supplementation (MMS) had lower risks of preterm and very preterm birth and low and very low birthweight compared with women who initiated IFAS.
