Micronutrient deficiencies in pregnancy worldwide: health effects and prevention

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.

Figures

Figure 1. The function and timing of micronutrients that affect outcomes in offspring

Insights on micronutrient function are primarily derived from reviews of data from in vitro studies, experimental animal models, observational data in human studies and a limited number of trials that have explored metabolic mechanisms and outcomes. The relevant time of action and the function of micronutrients is depicted, but the accumulation of fetal micronutrient stores, generally dependent on the status of the mother, is not. Availability of fetal micronutrient stores to support growth and developmental processes into infancy and beyond is, therefore, an implied pathway. Fol, folate.