Is Supplementation with Micronutrients Still Necessary during Pregnancy? A Review

Abstract

Introduction: Proper nutrition during pregnancy is important to prevent nutritional imbalances that interfere with pregnancy. Micronutrients play critical roles in embryogenesis, fetal growth, and maternal health, as energy, protein, vitamin, and mineral needs can increase during pregnancy. Increased needs can be met by increasing the intake of dietary micronutrients. Severe micronutrient deficiency or excess during pregnancy can have negative effects on fetal growth (intrauterine growth retardation, low birth weight, or congenital malformations) and pregnancy development (pre-eclampsia or gestational diabetes). We investigate whether it is necessary to continue micronutrient supplementation during pregnancy to improve women’s health in this stage and whether this supplementation could prevent and control pathologies associated with pregnancy. Aim: The present review aims to summarize evidence on the effects of nutritional deficiencies on maternal and newborn morbidity. Methods: This aim is addressed by critically reviewing results from published studies on supplementation with different nutrients during pregnancy. For this, major scientific databases, scientific texts, and official webpages have been consulted. PubMed searches using the terms “pregnancy” OR “maternal-fetal health” AND “vitamins” OR “minerals” OR “supplementation” AND “requirement” OR “deficiency nutrients” were performed. Results: There are accepted interventions during pregnancy, such as folic acid supplementation to prevent congenital neural tube defects, potassium iodide supplementation to correct neurodevelopment, and oral iron supplementation during the second half of pregnancy to reduce the risk of maternal anemia and iron deficiency. A number of micronutrients have also been associated with pre-eclampsia, gestational diabetes mellitus, and nausea and vomiting in pregnancy. In general, experimental studies are necessary to demonstrate the benefits of supplementation with different micronutrients and to adjust the recommended daily doses and the recommended periconceptional nutrition for mothers. Conclusions: Presently, there is evidence of the benefits of micronutrient supplementation in perinatal results, but indiscriminate use is discouraged due to the fact that the side effects of excessive doses are not known. Evidence supports the idea that micronutrient deficiencies negatively affect maternal health and the outcome of pregnancy. No single micronutrient is responsible for the adverse effects; thus, supplementing or correcting one deficiency will not be very effective while other deficiencies exist.

Review of Dietary Recommendations for Twin Pregnancy: Does Nutrition Science Keep Up with the Growing Incidence of Multiple Gestations?

“…It is known that high doses of this vitamin can damage the fetal central nervous system and cause different congenital defects [ 17 , 36 , 39 ]. According to some experts, scientific data (based on studies in women with a singleton pregnancy) do not justify routine vitamin A supplementation, and the same applies to vitamins E, B1, B2 and K [ 86 ]. Without appropriate scientific studies, it is difficult to explicitly state that the same approach should be adopted for a twin pregnancy.…”

“…The latest position statement of the US Preventive Services Task Force is very cautious and indicates there are too little data to estimate the benefits and risks of routine iron supplementation in pregnant women in order to prevent the adverse course of pregnancy and experts from this organization do not take a different stand with regard to multiple pregnancies [ 98 ]. The same approach is adopted by the American College of Obstetricians and Gynecologists, and just like the previous opinion, does not refer to iron supplementation in women pregnant with twins [ 86 , 99 ]. Routine iron supplementation for all women is also not recommended in Great Britain.…”

“…Some argue that, apart from a routine vitamin–mineral supplement, women pregnant with twins should be advised to take additional doses of magnesium and zinc because the requirements for these elements considerably rise [ 37 ], while others do not reckon these elements need supplementation [ 36 ]. A very important mineral component during pregnancy is, undoubtedly, iodine and most scientific societies recommend its supplementation at 150–200 µg per day [ 83 , 86 , 102 ]. It is unknown, however, whether such a dose is also appropriate for women pregnant with twins.…”

The effect of blister packaging Iron and Folate on adherence to medication and hemoglobin levels among pregnant women at National Referral Hospital antenatal clinics in a low to middle income country: a Randomised Controlled Trial (The IFAd Trial)

“…Folic acid deficiency around conception period is associated with neural tubal defects and other non-genetic congenital abnormalities (cleft lip and heart disease). It has been suggested that folic acid deficiency causes placental vasculopathy that contributes to spontaneous abortion, premature placenta abruption and preeclampsia [ 6 , 7 ]. Similarly, iron deficiency has been observed to decrease the weight of the newborn, increased premature delivery and other complications during delivery.…”

“…Similarly, iron deficiency has been observed to decrease the weight of the newborn, increased premature delivery and other complications during delivery. Iron is necessary for the placenta, uterine enlargement, red blood cell synthesis and fetal growth [ 7 , 8 ].…”