Suboptimal micronutrient intakes in pregnancy
Maternal nutrition in pregnancy is very important as it supports the health of the mother and unborn infant. With an increasing demand during pregnancy, suboptimal micronutrient intakes are however a recognized risk. Research suggests that in developing as well as developed countries, suboptimal intakes are prevalent.
Maternal nutrition influences fetal growth and birth outcomes. Worldwide, notable differences exist in dietary and nutrient intakes, ranging from severe micronutrient deficiencies in developing countries to suboptimal intakes in more developed regions.1-3 Suboptimal nutrient intake in pregnancy can impair fetal development, which is increasingly researched and recognized as a potential mediating factor in an infant’s future health.4
A recent meta-analysis of Blumfield et al. mapped micronutrient intakes in pregnant women from five regions: Europe, USA/Canada, United Kingdom, Australia/New Zealand and Japan. The combined results of 62 nutrient intake studies were analyzed and compared to the local estimated average nutrient requirements (EAR). This analysis showed that especially the average folate-, iron- and vitamin D-intakes were in the majority of cases lower than recommended in pregnant women from developed regions (figure 1).3
Figure 1: percent intake of the EAR per region and nutrient
Many women and children in developing countries suffer from severe malnutrition, making it one of the main health problems. Maternal undernutrition in general contributes to fetal growth restriction, increasing the risk of neonatal deaths and stunting in survivors by 2 years of age. Also, suboptimum breastfeeding results in an increased risk for mortality in the first 2 years. Black et al. estimated that maternal and child undernutrition represents the underlying cause of 3·1 million child deaths annually or 45% of all child deaths in 2011.5
In developing countries, especially supplies of the micronutrients vitamin A, iron, zinc and iodine in pregnancy have received considerable attention due to their role in maternal and perinatal health. A short overview on health effects of each deficiency is provided below and in table 1, the prevalence of deficiencies is listed.
Maternal vitamin A deficiency can cause visual impairment and possibly other health consequences. It is estimated that in 2011, 15% of pregnant women worldwide suffer from vitamin A deficiency (serum retinol < 0.70 micromole/L).5
Anemia (haemoglobin <110 g/L) is highly prevalent during pregnancy (19% worldwide). Evidence suggests that it can increase the risk of maternal mortality and adversely affect child development. Also, there is strong biological plausibility for a causal link between maternal iron deficiency anemia and adverse birth outcomes.5
Estimates from 2012 suggest that 17% of the world’s population is at risk of zinc deficiency. The effect of subclinical zinc deficiency in women of reproductive age and during pregnancy on health and development outcomes is poorly understood. Zinc deficiency has been suggested as a risk factor for impaired growth, immunity, and metabolic status of surviving offspring.5
Maternal iodine deficiency is of concern because of its relation to adverse effects on fetal development. Global estimates of iodine deficiency suggest that 28.5% of the world’s population or 1.9 billion individuals are iodine deficient, representing mostly mild deficiency.5
Table 1. Prevalence of deficiencies in children under 5 years and pregnant women.
- Abu-Saad K, Fraser D. Maternal nutrition and birth outcomes. Epidemiol Rev. 2010;32:5–25.
- Blumfield et al. Systematic review and meta-analysis of energy and macronutrient intakes during pregnancy in developed countries. Nutr Rev. 2012 Jun;70(6):322-36.
- Blumfield ML et al. A systematic review and meta-analysis of micronutrient intakes during pregnancy in developed countries. Nutr Rev. 2013 Feb;71(2):118-32.
- Christian P, Stewart CP. Maternal micronutrient deficiency, fetal development, and the risk of chronic disease. J Nutr. 2010 Mar;140(3):437-45. doi: 10.3945/jn.109.116327. Epub 2010 Jan 13.
- Black. et al. Maternal and child undernutrition and overweight in low-income and middle-income countries. Lancet 2013: 382(9890):427-451.