Key Points
Micronutrient deficiencies during pregnancy are a global public health concern, yet the full extent of their burden and health consequences are unclear due to infrequent and inadequate assessment
Micronutrient deficiencies have been linked to compromised conception, length of gestation, and fetal development and growth, which can lead to pregnancy loss, preterm delivery, small birth size, birth defects and long-term metabolic disturbances
Antenatal supplementation with multiple micronutrients can improve birth outcomes and merits policy and program consideration in low-income settings
Preconception and periconception intervention research is needed to further assess the full public health effect of micronutrient adequacy on pregnancy outcomes
Abstract
Micronutrients, vitamins and minerals accessible from the diet, are essential for biologic activity. Micronutrient status varies widely throughout pregnancy and across populations. Women in low-income countries often enter pregnancy malnourished, and the demands of gestation can exacerbate micronutrient deficiencies with health consequences for the fetus. Examples of efficacious single micronutrient interventions include folic acid to prevent neural tube defects, iodine to prevent cretinism, zinc to reduce risk of preterm birth, and iron to reduce the risk of low birth weight. Folic acid and vitamin D might also increase birth weight. While extensive mechanistic and association research links multiple antenatal micronutrients with plausible materno–fetal health advantages, hypothesized benefits have often been absent, minimal or unexpected in trials. These findings suggest a role for population context in determining health responses and filling extensive gaps in knowledge. Multiple micronutrient supplements reduce the risks of being born with low birth weight, small for gestational age or stillborn in undernourished settings, and justify micronutrient interventions with antenatal care. Measurable health effects of gestational micronutrient exposure might persist into childhood but few data exists on potential long-term benefits. In this Review, we discuss micronutrient intake recommendations, risks and consequences of deficiencies, and the effects of interventions with a particular emphasis on offspring.