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Fertility Blaze 2011 › Fertility Blaze Vol-1, No-7, 2011

ROLE OF Macro- and MICRONUTRIENTS IN PREGNANCY

ROLE OF Macro- and MICRONUTRIENTS IN PREGNANCY

Introduction

Pregnancy is a period when the metabolic demands of a woman increase with changes in her physiology and requirements of a growing fetus.1

Adequate maternal micronutrient status is especially critical during pregnancy and lactation. It is important to recognize that the status of the mother, right from the periconceptional period and throughout pregnancy and lactation represents a continuum, and that these three stages should not be considered separately. Moreover, the micronutrient status of the fetus and later the infant depends on adequate maternal status during pregnancy and lactation. It should also be recognized that multiple micronutrient deficiencies are likely to coexist when diets are inadequate. Some of these can contribute to poor pregnancy outcomes and infant development.2

During pregnancy, inadequate stores or intake of micronutrients can compromise the mother’s health by causing anemia, hypertension, complications of labor and even death. These deficiencies can affect the fetus as well, resulting in stillbirth, pre-term delivery, intrauterine growth retardation, congenital malformations, reduced immunocompetence and abnormal organ development.1

When several deficiencies are present, correcting just one may not yield the desired results. Similarly, even after all the deficiencies have been corrected, continued consumption of a diet poor in calories and protein may compromise some outcomes, such as fetal growth.1

A recent meta-analysis3   of studies done in low or middle income countries revealed that antenatal multimicronutrient supplementation led to a significantly reduced risk of low birth weight and improvement in the birth weight in comparison to iron/folic acid supplementation only.

Causes of macro- and micronutrient deficiencies2

  • Poor quality diet: This is the main cause of multiple micronutrient deficiencies, and is often due to an inadequate intake of animal source foods, i.e., meat and milk, especially in developing countries. Even in affluent countries, avoidance of meat and/or milk increases the risk of micronutrient depletion during pregnancy and lactation.
  • Gene polymorphisms can also cause micronutrient deficiencies by interfering with the absorption or altering the metabolism, leading to suboptimal maternal status of single nutrients.
  • Poor absorption: Certain dietary constituents, such as phytates and polyphenols, limit the absorption of nutrients, despite the consumption of adequate amounts of nutrients.
  • Diseases, such as malaria, and intestinal parasitic infections, also impair the metabolism of multiple micronutrients.
  • Increased requirement, as happens in pregnancy and/or lactation, increases the risk of inadequate intake.

Some important macronutrients and their deficiencies in pregnancy

Calcium

Calcium is required for the maintenance of skeletal, neuromuscular, and cardiac function.4

Deficiency of calcium may be associated with abnormal fetal development, pregnancy-induced hypertension, and pre-term delivery.1

Since the maternal skeleton does not provide calcium for the fetus’ needs, adequate calcium supplementation during pregnancy and lactation (1200 mg/day) is essential for fetal bone mineralization.5

Magnesium

Magnesium and calcium work in tandem. Magnesium relaxes muscles, while calcium stimulates muscles to contract. During pregnancy, magnesium helps build and repair the body’s tissues, and can prevent premature uterine contractions. Magnesium also helps build strong bones and teeth, regulates insulin and blood sugar levels, and helps certain enzyme function. There is evidence of its role in controlling cholesterol and irregular heartbeats.  6  

A compromised magnesium nutritional status may be involved in several disorders during pregnancy, such as hypertension, vasospasm, coagulation defects, premature delivery, intrauterine growth retardation and muscle cramping.7

Pregnant and lactating women require 310 mg of magnesium per day.5

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Some important micronutrients and their deficiencies in pregnancy

Iron

Iron is among the major trace elements required right from conception, throughout the pregnancy and during lactation. Iron stores at conception are a strong predictor of maternal iron status and risk of anemia in later pregnancy.8,9   It is also recognized that maternal iron status strongly affects the iron stores of the infant at birth.

Iron deficiency anemia is highly prevalent in women in developing countries. A deficiency of iron in the mother during pregnancy can result in preterm delivery and anemia,6   while iron deficiency during lactation may lead to mental retardation in the neonate.10,11      The recommended daily iron intake for pregnant women is 35 mg/day and for lactating women, 25 mg/day.5

Steps should be taken to ensure adequate maternal iron status early in pregnancy, throughout pregnancy and during the postpartum period.2

Increased iron requirements in pregnancy are often not met by changes in diet or absorption. Iron supplementation during pregnancy has been shown to improve iron stores and is recommended by national and international bodies.1

Zinc

Zinc is required to maintain structural integrity of proteins and regulate gene expression. It is recommended in the dose of 12 mg/day during pregnancy and lactation.5

Studies have shown that maternal zinc status was associated with birth weight, and zinc supplementation was found to lead to reduction in premature delivery, higher birth weight, and reduction in hypertension. One study12   showed that zinc supplementation during pregnancy improved fetal development by reducing fetal heart rate and increasing heart rate accelerations and variability, and fetal movements. In another study,13   maternal supplementation in pregnancy reduced morbidity of low birth weight infants in the first 6 months of life.

Vitamin D

Vitamin D aids in the absorption of calcium and phosphorous from dietary intakes, which are required for the formation of fetal skeleton.2   Deficiency of vitamin D during pregnancy may result in rickets or type 1 diabetes mellitus in the infant.14

Women whose clothing covers a high proportion of their skin, or whose skin is highly pigmented, are at greater risk of vitamin D deficiency. Even moderately low plasma 25-hydroxyvitamin D concentrations were found to be associated with poor fetal and infant skeletal growth and mineralization, and poor infant tooth mineralization. These biochemical and clinical signs of vitamin D deficiency were prevented by maternal supplementation with the vitamin.15  

The recommended daily intake of vitamin D during pregnancy and lactation is 600 IU/day.16

Iodine

Iodine is essential for fetal and neonatal growth and development. Severe iodine deficiency may result in abortion or stillbirth, congenital anomalies, neurological cretinism, or mental deficiency with deafness, spastic diplegia, squint and myxedematous cretinism.4

Despite universal salt iodization, intakes of iodine are often still inadequate. Pregnancy tends to increase the clinical and biochemical symptoms of iodine deficiency in women with marginal iodine status, resulting in abnormal thyroid hormone concentrations. It should be remembered that even mild maternal iodine deficiency can adversely affect fetal mental development; hence, maintaining an adequate iodine status in pregnancy is of utmost importance.17

It is recommended that pregnant women consume at least 200 μg of iodine per day.5

Manganese

Manganese helps in the formation of bone and cartilage. It is also a component of enzymes that play a role in the formation of carbohydrates, amino acids, and cholesterol. As part of a powerful antioxidant called manganese superoxide dismutase, it helps reduce oxidative stress.18

The recommended daily allowance of manganese is 2-5 mg/day in women, whether pregnant, lactating or not.5

Copper

Copper is a trace mineral, essential for forming red blood cells. This is especially important during pregnancy, when the blood supply doubles. Copper also enhances the body’s ability to mend tissues and break down sugars. During pregnancy, copper helps form the fetal heart, blood vessels, and the skeletal and nervous systems.19

Copper deficiency during pregnancy results in numerous gross structural and biochemical abnormalities that affect free-radical defenses, connective tissue metabolism, and energy production in fetal tissues. Even marginal copper deficiency might contribute to failure of implantation in more than 50% of cases, failure of 30% of successful implantations to reach term and serious congenital abnormalities in 3% of newborns delivered.20

The daily requirement of copper during pregnancy is 1.35 mg/day during pregnancy and lactation.5

Micronutrient supplementation during pregnancy

Efforts to prevent or treat micronutrient deficiencies should ideally be initiated even before a woman becomes pregnant. This will improve fertility and maternal health, and also bring down the incidence of birth defects.

The maternal intake of multiple micronutrients can be enhanced either by improving dietary quality or by prescribing multiple micronutrient supplements on the first antenatal visit. An observational study found a substantial reduction in preterm, very preterm, low birth weight and very low birth weight deliveries in women who started taking supplements in their first trimester as compared to those who did not.

Supplementation with multiple micronutrients is preferable to that with iron and folic acid alone, especially in developing countries where multiple deficiencies are prevalent.2

Conclusion

It is widely accepted that micronutrients have a major function in many periods of a woman’s life, particularly during pregnancy and lactation. There is considerable evidence supporting the role of various micronutrients in determining pregnancy outcomes, such as low birth weight and prematurity.

Inadequate stores or intake of micronutrients might have adverse effects both on the mother (hypertension, anemia, complications of labor) and the fetus (congenital malformations, pre-term delivery, intrauterine growth retardation). Micronutrient malnutrition during pregnancy is common, particularly in developing countries. Studies have shown that supplementation of certain trace elements and minerals could prevent some of the most severe adverse pregnancy outcomes. Supplementation with multiple micronutrients is preferable to that with iron and folic acid alone, especially in developing countries, where multiple deficiencies are more prevalent than single deficiencies.

References

  1. Black RE. Micronutrients in pregnancy. British Journal of Nutrition 2001;85(Suppl. 2):S193-S197.
  2. Allen LH. Multiple micronutrients in pregnancy and lactation: an overview. Am J Clin Nutr 2005;81(suppl): 1206S–12S.
  3. Shah PS, Ohlsson A. Effects of prenatal multi micronutrient supplementation on pregnancy outcomes: A meta-analysis. CMAJ 2009;180:E99–108.
  4. Lim CED, Yii MF, Cheng NCL. The role of micronutrients in pregnancy. Australian Family Physician 2009; 38(12): 980-984.
  5. National Institute of Nutrition. Nutrient Requirements and Recommended Dietary Allowances for Indians. A Report of the Expert Group of the Indian Council of Medical Research 2009. Available at http://www.pfndai.com/Draft_RDA-2010.pdf. Accessed on June 17, 2011.
  6. Magnesium in your pregnancy diet. Available at http://www.babycenter.com/0_magnesium-in-your-pregnancy-diet_659.bc. Accessed on June 3, 2011.
  7. Franz KB. Magnesium Intake during Pregnancy. Magnesium 1987;6:18-27.
  8. Bothwell TH. Iron requirements in pregnancy and strategies to meet them. Am J Clin Nutr 2000;72(suppl):257S– 64S.
  9. Casanueva E, Pfeffer F, Drijanski A, et al. Iron and folate status before pregnancy and anemia during pregnancy. Ann Nutr Metab 2003;47: 60–3.
  10. Dawson EB, McGanity WJ. Protection of maternal iron stores in pregnancy. J Reprod Med 1987;32:478–87.
  11. Casanueva E, Pfeffer F, Drijanski A, et al. Iron and folate status before pregnancy and anemia during pregnancy. Ann Nutr Metab 2003;47:60–3.
  12. Merialdi M, Caulfield LE, Zavaleta N, Figueroa A, Dominici F, Dipietro JA. Randomized controlled trial of prenatal zinc supplementation and the development of fetal heart rate. Am J Obstet Gynecol 2004;190: 1106–12.
  13. Osendarp SJ, van Raaij JM, Darmstadt GL, Baqui AH, Hautvast JG, Fuchs GJ. Zinc supplementation during pregnancy and effects on growth and morbidity in low birth weight infants: a randomised placebo controlled trial. Lancet 2001;357:1080 –5.
  14. Haider BA, Bhutta ZA. Multiple-micronutrient supplementation for women during pregnancy. Chichester, UK: John Wiley and Sons Ltd, 1993.
  15. Zeghoud F, Vervel C, Guillozo H, Walrant-Debray O, Boutignon H, Garabédian M. Subclinical vitamin D deficiency in neonates: definition and response to vitamin D supplements. Am J Clin Nutr 1997; 65:
    771– 8.
  16. Institute of Medicine of the National Academies. Dietary Reference Intakes for Calcium and Vitamin D. November 2010.
  17. Delange F, Wolff P, Gnat D, DramaixM, Pilchen M, Vertongen F. Iodine deficiency during infancy and early childhood in Belgium: does it pose a risk to brain development? Eur J Pediatr 2001;160:251– 4.
  18. Manganese in your pregnancy diet. Available at http://www.babycenter.com/0_manganese-in-your-pregnancy-diet_750.bc. Accessed on June 3, 2011.
  19. Copper in your pregnancy diet. Available at http://www.babycenter.com/0_copper-in-your-pregnancy-diet_677.bc. Accessed on June 3, 2011.
  20. Copper. Available at http://www.drlera.com/health_beauty/healthy_baby/copper.htm. Accessed on June 3, 2011.
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