Supplementation during pregnancy

 Although, in the general population, a healthy balanced diet should largely obviate the need for vitamin and mineral supplementation, pregnancy and lactation create extra nutritional demands that, for some individuals, may make supplementation advisable.

During pregnancy and especially while breastfeeding, a mother’s nutritional requirements change significantly and the recommended nutrient intake of vitamins and minerals increases. Maternal metabolism is altered by hormones that mediate the redirecting of nutrients to the placenta and mammary glands as well as the transfer of nutrients to the developing infant.

Risk factors resulting in the need for supplementation with vitamins in pregnancy

• Poor public awareness and lack of education results in lack of knowledge about adequate prenatal nutrition and care.
• Cultural beliefs with specific nutritional traditions and dietary taboos result in micronutrient deficiency having potential adverse consequences for both mothers and newborn infants.
•  Pregnancies are mostly unplanned in the western population, resulting in minimal time for folic acid reserve build up.
• Many people in developing countries exist on monotonous cereal- or legume based diets and has limited access to animal products or a variety of fruit and vegetables.
• Maternal micronutrient deficiencies may also exist due to gastro-intestinal disorders such as chronic diarrhoea resulting in malabsorption of nutrients.

Pregnancy related changes posing a risk for micronutrient deficiencies include

• Kidney function changes to handle the clearance of both foetal and maternal metabolic waste, resulting in increased urinary excretion of water-soluble vitamins (e.g. folate)
• By the third trimester, blood volume will have increased by 35–40% over the non-pregnant state, largely because of a 45–50% expansion of plasma volume and a 15–20% expansion of red blood cell mass. This then explains the increased need for iron, since it is metabolised in the production of red blood cells.
  

Vitamins

Folate

In South Africa, the RDA (recommended daily allowance*) of folic acid for pregnant women has remained unchanged since 1977.  This is despite the fact that since 2003, most cereals and bread products have been fortified in accordance with the Food Fortification Programme and thus contribute to the optimum levels of folic acid required.

In October 2003, South Africa embarked on a program of folic acid fortification of staple foods. They measured the change in prevalence of Neural Tube Defects (NTDs) before and after fortification and assessed the cost benefit of this primary health care intervention conducted among 12 public hospitals in four provinces of South Africa. The study showed a significant decline in the prevalence of NTDs following folic acid fortification in South Africa and declines of up to 30.5% were observed.

The Department of Health (2003) has set the level of fortification  of folic acid in wheat flour at 1.5 mg/kg and in maize meal at 2.21 mg/kg and it is well known that maize meal and bread are among the most widely consumed staple foods in South Africa, especially in the lower income groups.

It is recommended that folic acid should be taken for a minimum of one month before conception and for the first 12 weeks of pregnancy. The recommended dose of folic acid is at least 0.4mg daily to aid the prevention of neural tube defects (NTD). Where there is an increased risk of NTD (e.g. anticonvulsant medication, pre-pregnancy diabetes mellitus, previous child or family history of NTD) or with an increased risk for folate deficiency, (e.g. multiple pregnancies, haemolytic anaemia) a 5mg daily dose should be taken.

Vitamin B12

Vegetarians and vegans should be supplemented with vitamin B12 in pregnancy and lactation.

Vitamin D

Studies of pregnant women attending antenatal clinics have found a disturbing frequency of vitamin D deficiency in some communities. Women at increased risk include those with reduced sunlight skin exposure e.g. veiled women, those who use sunscreen on a regular basis and dark-skinned women. These patients should be supplemented with additional vitamin D during pregnancy.

Other Vitamin Supplementation

There is little evidence to support “routine” supplementation of other vitamins in pregnancy such as vitamin A, C & E.

Minerals

Iron

The iron demands of pregnancy and lactation are particularly pronounced due to the expanded red cell volume, blood loss around the time of delivery and the demands of the developing fetus and placenta. Iron supplementation will generally be recommended to pregnant women.  All women should have their haemoglobin level checked at the first antenatal visit and again at approximately 28 weeks’ gestation.

Calcium

If a woman avoids dairy in her normal  diet (e.g. lactose intolerant) and does not consume alternative high calcium food (e.g. calcium enriched soya milk), calcium supplementation is recommended at 1000mg/day.

Iodine

Iodine deficiency appears to be increasing in frequency. This may in part be related to a reduction in salt intake. Recent research suggests that iodine supplementation is mandatory in areas of regional deficiency. Women who are pregnant, breast feeding or considering pregnancy should take an iodine supplement of 150 micrograms each day.

Conclusion

The purpose of multiple-micronutrient supplementation during pregnancy is twofold: to improve pregnancy outcomes by reducing pregnancy complications, reducing the risk of developmental and common birth defects and to improve breast-milk quality.