Prenatal Nutrition

Author: Corenthian J Booker, MD, Staff Physician, Department of Obstetrics and Gynecology, Penn State Hershey Medical Center
Coauthor(s): Serdar H Ural, MD, Associate Professor of Obstetrics and Gynecology and Radiology, Director, Division of Maternal-Fetal Medicine, Medical Director, Labor and Delivery Suite, Penn State University College of Medicine

Background

The fields of obstetrics and nutrition have changed over the last few decades, greatly affecting the field of prenatal nutrition. The importance of nutrition in pregnancy cannot be overstated. It maintains maternal energy requirements, provides substrate for the development of new fetal tissues, and builds energy reserves for postpartum lactation. Recommendations for prenatal nutrition have traditionally been directed at 2 clinical arenas, weight gain in pregnancy and dietary intake in pregnancy.

Weight Gain and Pregnancy

An infant's birth weight is affected by many factors, including the mother's prepregnancy weight-for-height value and weight gain during pregnancy. Prepregnancy weight-for-height value is expressed as body mass index (BMI). BMI is defined as weight in kilograms divided by the square of height in meters. In 1959, the Metropolitan Life Insurance Company defined its weight-for-height standards by BMI. These standards are in common use today.

Underweight is defined as a BMI of less than 19.8. Normal weight is defined as a BMI of 19.8-26, which corresponds to between 25% and 75% of the expected weight-for-height value. Overweight is defined as a BMI of 26-29. Lastly, obesity is defined as a BMI that exceeds 29. Birth weight is affected by prepregnancy BMI independent of actual weight gain during pregnancy. Women who are underweight are at increased risk for low birth weight babies; women who are overweight or obese are at increased risk for macrosomic infants. Macrosomia is variably defined as weight exceeding 4000 g, 4500 g, or the 90th percentile. Macrosomic infants are at increased risk for shoulder dystocia and brachial plexus injuries.

Morbid obesity is defined by a BMI exceeding 35. Morbidly obese patients are at increased risk for preeclampsia, nonreassuring fetal heart tracings, meconium aspiration, late intrauterine fetal death, and early neonatal death.1

Of course, birth weight is also affected by weight gain during pregnancy. Although weight should be gained throughout pregnancy, it is most critical in the second trimester. Even if overall weight gain is poor, birth weight is usually acceptable with appropriate second-trimester weight gain. The following table relates low birth weight to both prepregnancy weight and pregnancy weight gain.

Rates of Low Birth Weight (<2500 g) by Weight and Weight Gain

 

Table
Pregnancy
Weight Gain, lb
Prepregnancy Weight, lb
<110 110-129 130-149 >150
<16 30% 20% 15% 7-8%
25-35 7-8% 6-7% 4-5% 3-4%
>35 5-6% 3-4% 3-4% 3-4%
Pregnancy
Weight Gain, lb
Prepregnancy Weight, lb
<110 110-129 130-149 >150
<16 30% 20% 15% 7-8%
25-35 7-8% 6-7% 4-5% 3-4%
>35 5-6% 3-4% 3-4% 3-4%

In 1990, the Institute of Medicine issued recommendations for weight gain during pregnancy.2 These recommendations are based on prepregnancy BMI. Women who are underweight are advised to gain a total of 12.5-18 kg (28-40 lb). This translates to 0.5 kg/wk in the second and third trimesters. Women of normal weight are advised to gain a total of 11.5-16 kg (25-35 lb), or 0.4 kg/wk, in the second and third trimesters. Women who are overweight or obese should limit their weight gain to 7-11.5 kg (15-25 lb), or 0.3 kg/wk, in the second and third trimesters.

Dieting during pregnancy is never recommended, even for patients who are morbidly obese. Severe restriction of energy (caloric) intake is associated with a 250-g decrease in average birth weight. Because of the expansion of maternal blood volume and construction of fetal and placental tissues, some weight gain is essential for a healthy pregnancy.

Weight gain within these parameters is associated with a lower rate of cesarean delivery, fewer infants with growth restriction or macrosomia, and a decreased incidence of postpartum obesity. Nevertheless, only 30-40% of pregnant women achieve appropriate weight gain.3 Further evaluation is needed if weight gain is persistently slow or does not equal 10 lb by mid pregnancy.

Diet in Pregnancy

The demands of pregnancy necessitate additional dietary requirements. Obviously, additional energy (caloric) intake is required to support recommended weight gain. Because energy requirements in pregnancy are increased by 17% over the nonpregnant state, a woman of normal weight should consume an additional 126 kJ/d (300 kcal/d); however, this energy should be of high nutrient density. Nutrient density reflects the amount of protein, vitamins, and minerals per 418 kJ (100 kcal) of food.

Protein should comprise 20% of a normal pregnancy diet. The recommended daily allowance (RDA) in pregnancy is 60 g. Fortunately, most American diets already contain more than enough protein. Pregnant women should be aware that many animal sources of protein are very high in fat and might contribute to excessive weight gain; therefore, animal proteins should be taken sparingly. Fat should only comprise 30% of a normal pregnancy diet. Carbohydrates should comprise the remaining 50%.

A sample diet for normal pregnancy is based on the food pyramid and should include 6-11 servings of grains; 3-5 servings of vegetables; 2-4 servings of fruit; 3-4 servings of dairy; 2-3 servings of meats, beans, or nuts; and 1 serving of sweets. Total energy intake should vary by BMI, but the average recommendation is 10,460 kJ/d (2500 kcal/d).

Vitamins in Pregnancy

The following recommendations are provided by the American Academy of Pediatrics and American College of Obstetricians and Gynecologist.2

Vitamin A

Vitamin A, a fat-soluble vitamin, is important for maintenance of visual function. Its main influence is on the retina, but it also aids glycoprotein synthesis and promotes cellular growth and differentiation in other tissues. Vitamin A is found in green leafy vegetables and yellow-orange vegetables. The nonpregnancy RDA is 700 mcg, the pregnancy RDA is 770 mcg. The lactation RDA is 1300 mcg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended. Doses exceeding 15,000 IU/d, often used to treat acne, are associated with an increased risk of birth defects and should not be used in pregnancy; however, alpha-carotene, a vitamin A precursor, is not teratogenic.

Vitamin B-1

Vitamin B-1, also known as thiamine, is a water-soluble B-complex vitamin. It is involved in the release of energy from cells. Its food sources include milk and raw grains. The RDA is 1.1 mg. In both pregnancy and lactation, the RDA increases to 1.4 mg. Well-balanced diets provide the pregnant and lactating RDA; therefore, routine supplementation is not recommended.

Vitamin B-2

Vitamin B-2, also known as riboflavin, is a water-soluble B-complex vitamin. It is also involved in the release of energy from cells. Vitamin B-2 is found in green vegetables, milk, eggs, cheese, and fish. The RDA is 1.1 mg. In pregnancy, the RDA increases to 1.4 mg; in lactation, it increases to 1.6 mg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin B-6

Vitamin B-6, also known as pyridoxine, is a water-soluble B-complex vitamin. It is important in protein, carbohydrate, and lipid metabolism. It is also involved in the synthesis of heme compounds. Vitamin B-6 is found mostly in vegetables. The RDA is 1.2-1.5 mg. The pregnancy RDA is 1.9 and in lactation, the RDA increases to 2 mg. Well-balanced diets provide the pregnant and lactating RDA; therefore, routine supplementation is not recommended.

Vitamin B-12

Vitamin B-12, a water-soluble B-complex vitamin, is essential for DNA synthesis and cell division. It is found in animal proteins. Deficiency is usually secondary to compromised intestinal function. Dietary deficiency is rare, but it is occasionally encountered in persons who follow strict vegan diets. The RDA is 2.4 mcg. The pregnancy RDA is 2.6 mcg. The RDA increases to 2.8 mcg with lactation. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin C

Vitamin C, also known as ascorbic acid, is a water-soluble vitamin with numerous functions. These include reducing free radicals and assisting in procollagen formation. Vitamin C is found in fruits and vegetables. Chronic deficiency impairs collagen synthesis and leads to scurvy. The RDA is 75 mg. The pregnancy RDA is 85 mg. The RDA increases to 120 mg with lactation. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin D

Vitamin D, a fat-soluble vitamin, is found in fortified milk. Exposure to ultraviolet light is necessary for vitamin conversion. Deficiency of vitamin D is associated with tooth enamel hypoplasia. The RDA in both pregnancy and lactation is 5 mcg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin E

Vitamin E, a fat-soluble vitamin, is an important antioxidant. It is found in animal protein and fats. Deficiency is not a major issue in obstetrics but has been implicated in newborn hemolytic anemia. The RDA is 15 mg. The pregnancy RDA is 15 mg; the lactation RDA is 19 mg. Well-balanced diets provide the RDA for women who are pregnant or lactating; therefore, routine supplementation is not recommended.

Vitamin K

Vitamin K, a fat-soluble vitamin, is required for synthesis of clotting factors VII, IX, and X. It is found in green leafy vegetables, tomatoes, dairy products, and eggs. Transportation of vitamin K from mother to fetus is limited; nevertheless, significant bleeding problems in the fetus are rare. However, newborn infants are often functionally deficient in vitamin K and receive parenteral supplementation at birth. The RDA is 90 mg. In pregnancy and lactation, the RDA stays at 90 mg. Well-balanced diets provide the RDA for women who are pregnant or lactating RDA; therefore, routine supplementation is not recommended.

Folic acid

Folic acid, a water-soluble B-complex vitamin, is important for DNA synthesis and cell replication. It is found in fortified grains, dried beans, and leafy greens.4 Much has been written about folic acid and pregnancy. Deficiency in pregnancy has been linked with maternal megaloblastic anemia and fetal neural tube defects. The RDA is 0.4 mg. The pregnancy RDA is 0.6 mg; the RDA decreases to 0.5 mg in lactation.

In 1998, the US Food and Drug Administration mandated fortification of grains with folate. The degree of fortification was calculated to provide only 0.1 mg/d of dietary folate. This was enacted to avoid having supplemental folate mask evidence of vitamin B-12 deficiency in susceptible populations, especially elderly persons. Cereal fortification has resulted in a 32% decrease in the prevalence of elevated maternal serum alpha-fetoprotein values5 and a 25% decline in the prevalence of open neural tube defects6 .

Despite fortification, sufficient folic acid is not provided by the average American diet and routine supplementation of 0.4 mg/d is recommended for healthy women. Folate supplements should be administered 3 months prior to conception and throughout the first trimester. If the mother has a prior child affected by a neural tube defect, supplementation in the subsequent pregnancy should be increased to 4 mg/d.

Niacin

Niacin is a water-soluble vitamin involved in the release of energy from cells. It is found in poultry, fish, and nuts. Deficiency results in pellagra. The RDA is 14 mcg. In pregnancy, the RDA increases to 18 mcg, and to 17 mcg in lactation. Well-balanced diets provide the RDA for women who are pregnant and lactating; therefore, routine supplementation is not recommended.

Minerals and Trace Elements in Pregnancy

Iron

Iron is essential to the production of hemoglobin. Its dietary sources include animal protein, dried beans, fortified grains, and any food cooked in cast iron cookware. Despite its numerous sources, women have difficulty maintaining iron balance using only a healthy diet. A well-balanced diet with 10,460 kJ/d (2500 kcal) contains approximately 15 mg of elemental iron; however, the absorption of iron is very inefficient and only approximately 10% of this is absorbed. With each normal menses, 12-15 mg of elemental iron is lost. Estimates indicate that a woman's diet must include 1.5-2 mg/d of elemental iron to compensate for menstrual losses alone. In pregnancy, 500 mg of additional iron is needed to expand maternal red cell mass. Another 500 mg is needed to supply fetal and placental tissues. On average, an additional 3 mg/d of elemental iron must be absorbed from dietary sources.

The RDA for elemental iron reflects these increased requirements. The RDA for women who are not pregnant is 15 mg, 1.5 mg of which is absorbed. In pregnancy, the RDA is 30 mg, 3 mg of which is absorbed. During lactation, the RDA returns to 15 mg. Well-balanced diets do not provide the pregnancy RDA for elemental iron; therefore, iron supplementation is recommended in normal pregnancy.

Various iron preparations are commercially available, and each delivers a slightly different amount of elemental iron. These preparations include ferrous sulfate, ferrous fumarate, ferrous gluconate, and polysaccharide iron complex. Pure elemental iron is available in 50-mg caplets of carbonyl iron. Providers should be aware of the elemental iron contained in any one specific preparation, and they should understand that only 10% of this is absorbed from the maternal gut. Absorption is enhanced by concurrent ingestion of foods containing vitamin C. Usually, one dose of any preparation containing at least 30 mg of elemental iron meets the RDA. Larger doses are required only to treat maternal iron deficiency anemia and only serve to constipate patients without anemia. Physicians should remember that iron competes with zinc at absorption sites. The clinical implications of this are discussed below in the zinc section.

Iron deficiency anemia is one of the most common pregnancy complications. Screening for iron deficiency anemia is recommended at the first prenatal visit and, thereafter, as indicated. Iron deficiency anemia is suggested if the complete blood cell count suggests a microcytic, hypochromic anemia. Confirmatory test results include a reduced serum iron level, increased total iron-binding capacity, decreased transferrin saturation, and reduced serum ferritin levels. If a provider is unable to perform the complete battery of confirmatory tests, the serum iron and ferritin levels usually suggest the correct diagnosis. Treatment is increased oral iron supplementation.

Many studies have shown that high hemoglobin values are associated with adverse pregnancy outcomes; however, iron supplementation cannot, in itself, raise hemoglobin to these levels.7 Any adverse outcomes are more likely secondary to underlying conditions responsible for high hemoglobin values.

Calcium

Calcium is a major component of bone; therefore, large quantities of calcium are required in pregnancy for construction of fetal tissues, especially in the third trimester. Pregnant women younger than 25 years also still require calcium for maternal bone mass. Hormonal adaptations and increased intestinal absorption protect maternal bone while meeting fetal calcium requirements. A well-balanced diet provides adequate calcium to meet all of these needs, and supplementation is not recommended. The RDA for nonpregnant, pregnant, and lactating women is 1000 mg.8

Calcium is found in dairy products and leafy green vegetables such as collard, kale, turnip, and mustard greens. Vitamin D is required for calcium absorption.

Phosphorus

Along with calcium, phosphorus is required for bone formation. Maternal serum inorganic phosphorus levels remain constant during pregnancy because of maternal adaptations. The RDA for nonpregnant, pregnant, and lactating women is 700 mg. Well-balanced diets easily provide the RDA for nonpregnant, pregnant, and lactating women; supplementation is not recommended. In fact, phosphorus is not usually in vitamin supplements.

Zinc

Zinc is involved in nucleic acid and protein metabolism; therefore, zinc is important in early gestation. The RDA is 8 mg. The RDA for pregnant women is 11 mg, which increases to 12 mg during lactation. Well-balanced diets provide the RDA for women who are pregnant and lactating, and supplementation is not recommended. Both iron and copper compete with zinc at absorption sites; therefore, zinc supplementation is recommended when elemental iron supplementation exceeds 60 mg/d. Likewise, whenever zinc supplements are used, copper should also be supplemented. Different prenatal vitamin formulations contain different amounts of copper and zinc. Usually, copper or zinc supplementation can be accomplished by careful selection of a prenatal vitamin formulation.

Sodium

Sodium is present in large quantities in the average American diet. It has received much attention. The RDA is 1.5 mg during pregnancy, lactation, and the nonpregnancy state. Whether pregnant or not, sodium should neither be restricted nor used excessively. Well-balanced diets "salted to taste" satisfy sodium requirements and obviate any need for supplementation. Pregnant women should remember that most processed and pre-prepared foods are high in sodium.

Prenatal Vitamin Supplements

A standard prenatal vitamin formulation contains the following supplements:

  • Iron - 30 mg
  • Zinc - 15 mg
  • Calcium - 250 mg
  • Vitamin B-6 - 2 mg
  • Folate - 0.4 mg
  • Vitamin C - 50 mg
  • Vitamin D - 5 mcg

Of course, contents vary by individual formulation, and nutrient supplementation should be chosen with attention to individual patient needs. A normal pregnancy and a well-balanced diet generally provide the RDA of all nutrients except elemental iron and folate, both of which must be supplemented. Prenatal vitamins are not otherwise necessary for every patient; however, these supplements are routinely prescribed to most patients for various important reasons. A major reason is that a nutritionally compromised pregnancy can be difficult to identify, and the potential benefits of routine supplementation overshadow any risk that can be attributed. Also, the psychological impact of supplementation cannot be overlooked. Many patients are uncomfortable with the idea of foregoing prenatal vitamins and are reassured by their prescription.

Shah et al conducted a systematic literature review of prenatal multimicronutrient supplementation on pregnancy outcomes. A significant reduction in risk of low birth weight was observed for mothers taking the mulitmicronutrients compared those taking with placebo or iron-folic acid supplementation. Birth weight was significantly higher in newborns in the multimicronutrient group compared with the iron-folic acid supplementation group. No significant differences were noted between multimicronutrients, iron-folic acid supplementation, or placebo on the risk of preterm birth or small-for-gestational-age infants.9

Special Considerations

Lactose intolerance

Lactose intolerance is especially common among women of African, Asian, and Middle Eastern descent. These women may have a difficult time getting adequate calcium in their diet. Encourage these women to drink lactose-free dairy products or calcium-enriched orange juice or soy milk; however, if their daily calcium intake is less than 600 mg (one serving of calcium-rich food), they will benefit from calcium supplementation. Many over-the-counter preparations are readily available. The total daily divided dose should be 500-1000 mg. The maximum tolerable daily divided dose is 2500 mg. If a woman is unable to tolerate any dairy products and has limited exposure to sunlight, she may also require supplemental vitamin D (400 IU/d). This scenario may arise in women who live in extreme northern latitudes. It may also occur in women who wear purdah, as is common among Muslims and women of Middle Eastern descent.

Vegetarian and vegan diets

Vegetarian diets are becoming increasingly prevalent. Well-balanced vegetarian diets that include dairy products provide adequate energy and nutrient intake and do not require special supplementation; however, vegan diets include no animal products whatsoever, including, meat, dairy, and eggs. A vegan diet, even if well balanced in all other respects, may be deficient in vitamins D and B-12. It may also be extremely low in fat, making satisfaction of energy requirements a challenge. Pregnant women who follow vegan diets require 400 IU/d of supplemental vitamin D, 2 mcg/d of supplemental vitamin B-12, and careful attention to energy intake.

Exercise

Although regular exercise in pregnancy is encouraged, athletes must give special attention to the nutritional demands of pregnancy. Both during exercise and at rest, women use carbohydrates faster when they are pregnant. Thus, they are prone to hypoglycemia. Exercise stimulates glucose use, which might further limit fetal access to nutrients. Pregnant women who exercise regularly are advised to increase their carbohydrate intake to compensate for their increased use.

Adolescents

The pregnant adolescent may also require careful attention to energy intake. Younger women may have increased energy requirements to satisfy the demands of ongoing maternal growth. At the same time, body image concerns may deter younger women from gaining the weight needed to support a healthy pregnancy. Consultation with nutritionists and social workers (eg, counselors) may be helpful if these dietary issues arise.

Multiple gestations

Women carrying multiple gestations have increased nutritional requirements. The recommended weight gain for twin gestations is 16-20 kg (35-44 lb). This amount of weight gain requires approximately 630 additional kJ/d (150 kcal/d) over the dietary requirements of singleton pregnancies. Women with triplets should gain 50 lb.10 Of course, these recommendations should be adjusted for prepregnancy BMI. Nutrient requirements are also increased in multiple gestations. Routine prenatal vitamin and mineral supplementation is recommended. The suggested amount of folic acid supplementation is 1 mg/d. Elemental iron requirements are often increased, requiring more frequent doses of iron supplements. Lastly, vitamin B-6 requirements are increased. The recommended supplementation for women with multiple pregnancies is 2 mg/d.

Hyperemesis gravidarum

Hyperemesis gravidarum is a common complication of early pregnancy. In the first trimester, when weight gain is not yet essential to fetal growth, mild hyperemesis is unlikely to affect fetal development. The initial therapy is avoidance of large boluses of food. Frequent, small meals and snacks are preferred. If this fails, patients may respond to vitamin B-6, 25 mg 3 times a day. When hyperemesis precludes all oral intake, severe dehydration and ketosis may result, which requires inpatient management and intravenous rehydration with a glucose-containing solution. In rare instances when starvation is prolonged, patients must be fed parenterally, by total parenteral nutrition or peripheral parenteral nutrition.

Eating disorders

Eating disorders are common in women during their reproductive years. Anorexia nervosa commonly results in amenorrhea and is not often observed in pregnancy. However, bulimia may complicate pregnancy. As in hyperemesis, bulimia is unlikely to affect fetal development in the first trimester. If it becomes persistent, the severe energy restriction may compromise fetal growth. Consultation with a psychiatrist is essential.

Malabsorption syndromes

Likewise, malabsorption syndromes and inflammatory bowel disease may compromise fetal growth. Increased ultrasonographic surveillance may aid in early detection of a growth-impaired pregnancy. Special diets and supplements may be required; therefore, these patients must be treated in conjunction with a gastroenterologist.

Bariatric surgery

The prevalence of obesity, and therefore bariatric surgery, has increased dramatically over the last 20 years, leading to an increased number of pregnancies following bariatric/gastric bypass surgery. 

Several types of procedures are performed. In general, the classes include gastric restriction such as banding, combined gastric restriction, and bypass such as the roux-en-Y gastric bypass (RGB) and the combined gastric restriction and intestinal malabsorption such as the biliopancreatic diversion (BPD). In general, gastric restriction limits the amount of food eaten, causing early satiety by decreasing the size of the stomach and decreasing the size of the outlet. The RGB has 2 components, the gastric restriction and also bypassing the duodenum and directly connecting the stomach to the jejunum, thus creating early satiety, mild malabsorption, and causing dumping syndrome when a large sugar load is ingested. The BPD combines gastric restriction and a greater degree of malabsorption. The frequency of the RGB is 70%, BPD 12% and gastric banding 16% (but includes several forms of banding).

Nutritional complications are not seen in purely restrictive procedures, whereas the malabsorption procedures cause most of the nutritional complications seen in patients undergoing bariatric surgery. Patients undergoing BPD and RGB often develop protein malnutrition, anemia, and deficiencies of iron, folate, calcium, vitamin B-12, and the lipid soluble vitamins such vitamins D, K, E and A.

No standard of care has been set related to the frequency of monitoring nutritional deficiencies of patients who become pregnant after undergoing bariatric surgery. However, in a recent review of bariatric surgery patients were advised to not get pregnant during the more rapid phase of weight loss because of an increased risk for micronutrient and macronutrient deficiencies during this period.11 General surgeons have a wide range of practice for monitoring micronutrient and macronutrient deficiencies.

The American College of Obstetrics and Gynecology recommends that all patients have preconceptional counseling and prenatal assessment of their nutritional status and, where appropriate, replacement of vitamin B-12, folic acid, iron, and calcium.12 In addition, the assessment of other potential nutritional deficiencies should be based on the practitioner’s clinical judgment. Pregnancy outcomes are favorable overall. Researchers have determined that pregnancies after bariatric surgery are less likely to be complicated by gestational diabetes, hypertension, macrosomia, and cesarean delivery than are pregnancies of obese women who have not had the surgery but can be associated with adverse perinatal outcomes. Consultation with a perinatologist may be helpful.

Poverty

Poverty nearly doubles the rate of insufficient weight gain. Nutritional counseling may assist patients who are impoverished in identifying low-cost foods with high-nutrient density. The federal Women, Infants, and Children (WIC) program, administered through the US Department of Agriculture Food and Nutrition Service, is a valuable resource for women who are impoverished (see Food and Nutrition Service ).

International issues

In the United States, the vast majority of pregnant women enjoy good nutrition; however, in much of the developing world, pregnant women may experience nutritional deficiencies not commonly observed in the United States.

For example, diets that are severely deficient in calcium have been associated with an increased prevalence of hypertensive disorders of pregnancy. Zinc deficiency, which can occur with poor dietary intake or increased dietary iron or copper intake, is associated with an increased risk of congenital anomalies, pregnancy loss, intrauterine growth restriction, and preterm delivery. Iodine deficiency is associated with fetal loss and cretinism. Vitamin A deficiency is widespread in developing nations and is associated with night blindness, intrauterine growth restriction, and preterm delivery. Vitamin D deficiency, which occurs mainly in women who have limited exposure to sunlight, is associated with neonatal tetany, rickets, and abnormal tooth development.

Thus, micronutrient supplementation may be beneficial to the public health of developing nations.13 When administering large doses of supplemental iron, remember that the increased serum hemoglobin level associated with iron supplementation can result in a greater attack rate of clinical malaria. Thus, malarial prophylaxis is indicated when large doses of elemental iron are given to pregnant women in endemic areas.

Keywords

gestational complications, pregnancy complication, birth defects, obstetrics, obstetrical complications, pregnancy, nutrition, maternal malnutrition, fetal malnutrition, maternal-fetal medicine, maternal energy requirements, birth weight, body mass index, BMI, fetal weight, maternal weight, macrosomia, lactation, pellagra, neural tube defects, folate deficiency, megaloblastic anemia, hyperemesis gravidarum, morning sickness, multiple gestation, multiple pregnancy, twin pregnancy, triplet pregnancy, bulimia, malabsorption syndrome, inflammatory bowel disease

 

References

  1. Cedergren MI. Maternal morbid obesity and the risk of adverse pregnancy outcome. Obstet Gynecol . Feb 2004;103(2):219-24. [Medline] .

  2. Institute of Medicine. Nutrition during pregnancy: weight gain and nutrient supplements . Washington, DC: National Academy Press; 1990.

  3. Hickey CA. Sociocultural and behavioral influences on weight gain during pregnancy. Am J Clin Nutr . May 2000;71(5 Suppl):1364S-70S. [Medline] .

  4. American College of Obstetricians and Gynecologists. Nutrition and Women . Washington, DC: ACOG Technical Bulletin; 1996.

  5. Evans MI, Llurba E, Landsberger EJ, et al. Impact of folic acid fortification in the United States: markedly diminished high maternal serum alpha-fetoprotein values. Obstet Gynecol . Mar 2004;103(3):474-9. [Medline] .

  6. Centers for Disease Control and Prevention. Spina bifida and anencephaly before and after folic acid mandate--United States, 1995-1996 and 1999-2000. MMWR Morb Mortal Wkly Rep . May 7 2004;53(17):362-5. [Medline] .

  7. Yip R. Significance of an abnormally low or high hemoglobin concentration during pregnancy: special consideration of iron nutrition. Am J Clin Nutr . Jul 2000;72(1 Suppl):272S-279S. [Medline] .

  8. Allen LH. Women's dietary calcium requirements are not increased by pregnancy or lactation. Am J Clin Nutr . Apr 1998;67(4):591-2. [Medline] .

  9. Shah PS, Ohlsson A. Effects of prenatal multimicronutrient supplementation on pregnancy outcomes: a meta-analysis. CMAJ . Jun 9 2009;180(12):E99-108. [Medline] .

  10. Brown JE, Carlson M. Nutrition and multifetal pregnancy. J Am Diet Assoc . Mar 2000;100(3):343-8. [Medline] .

  11. Karmon A, Sheiner E. Pregnancy after bariatric surgery: a comprehensive review. Arch Gynecol Obstet . May 2008;277(5):381-8. [Medline] .

  12. ACOG Committee Opinion number 315, September 2005. Obesity in pregnancy. Obstet Gynecol . Sep 2005;106(3):671-5. [Medline] .

  13. Ladipo OA. Nutrition in pregnancy: mineral and vitamin supplements. Am J Clin Nutr . Jul 2000;72(1 Suppl):280S-290S. [Medline] .

  14. Tofail F, Persson LA, El Arifeen S, Hamadani JD, Mehrin F, Ridout D, et al. Effects of prenatal food and micronutrient supplementation on infant development: a randomized trial from the Maternal and Infant Nutrition Interventions, Matlab (MINIMat) study. Am J Clin Nutr . Mar 2008;87(3):704-11. [Medline] .

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