The plausibility of micronutrient deficiencies being a significant contributing factor to the occurrence of pregnancy complications.

Numerous studies support the concept that a major cause of pregnancy complications can be suboptimal embryonic and fetal nutrition. Although the negative effects of diets low in energy on pregnancy outcome are well documented, less clear are the effects of diets that are low in one or more essential micronutrients. However, several observational and intervention studies suggest that diets low in essential vitamins and minerals can pose a significant reproductive risk in diverse human populations. Although maternal nutritional deficiencies typically occur as a result of low dietary intakes of essential nutrients, nutritional deficiencies at the level of the conceptus can arise through multiple mechanisms. Evidence from experimental animals supports the concept that in addition to primary deficiencies, secondary embryonic and fetal nutritional deficiencies can be caused by diverse factors including genetics, maternal disease, toxicant insults and physiological stressors that can trigger a maternal acute phase response. These secondary responses may be significant contributors to the occurrence of birth defects. An implication of the above is that the frequency and severity of pregnancy complications may be reduced through an improvement in the micronutrient status of the mother.