Growth of the fetus (the unborn baby; Box 11-1) may be affected by various maternal factors, for example, the ingestion, digestion, absorption, and metabolism of nutrients. The fetus is dependent on these processes and transfer of nutrients through the placenta (the organ that allows the transfer of maternal nutrients to the fetus via the umbilical cord—referred to as the afterbirth at the time of delivery). An intact placenta of good size is critical for ideal growth of the fetus.

Box 11-1 Fetal Development

FIRST TRIMESTER (EMBRYO; CRITICAL STAGE)

Organs develop (4 to 12 weeks)

Central nervous system develops (4 to 12 weeks)

Skeletal structure hardens from cartilage to bone (4 weeks)

SECOND TRIMESTER (FETUS)

Growth and development continue (13 to 40 weeks)

Teeth calcify (20 weeks)

Fetus can survive outside womb (24 weeks)

THIRD TRIMESTER TO BIRTH

Growth and development continue

Storage of iron and other nutrients (36 to 40 weeks; premature babies often deficient in iron)

Development of necessary fat tissue (36 to 40 weeks)

The impact of maternal nutrition does not stop at birth. Breastfeeding, preparation for a future successful pregnancy, and even the infant’s feeding environment are all influenced by the mother’s nutrition. A well-nourished mother is better able to cope with the demands of infant care, and a well-nourished infant displays a pleasant disposition, facilitating the return of the mother’s strength and vitality. The relationship between maternal and infant nutrition is very much reciprocal.

To promote healthy outcomes during pregnancy the American Dietetic Association advises optimal weight gain; physical activity as appropriate; a varied diet that follows the 2005 Dietary Guidelines for Americans; vitamin and mineral supplementation appropriate to needs; avoidance of alcohol, tobacco, and drugs; and safe food handling. Women who are not meeting these goals or have chronic health problems can benefit from a referral to a registered dietitian (Kaiser and colleagues, 2008).

A well-balanced diet will help the fetus grow well and allow the mother to stay healthy for future pregnancies. Table 11-1 shows a sample menu to promote a healthy pregnancy.

Table 11-1

Sample Meal Plans for Pregnancy

	PREGNANT WOMAN	PREGNANT ADOLESCENT
Breakfast*	Orange juice,^† 1 c	Orange juice,† 1 c
	Shredded wheat	Shredded wheat
	Scrambled egg	Scrambled egg
	Toast, 1 slice	Toast, 2 slices
	Milk, 1 c	Butter or margarine
	Decaffeinated coffee	Marmalade†
		Milk, 1 c
Lunch	Tuna sandwich on whole-grain bread	Tuna sandwich on whole-grain bread
	Carrot and green pepper sticks	Carrot and green pepper sticks
	Oatmeal cookies†	Cheese cube
	Milk, 1 c	Oatmeal cookies†
		Fresh fruit
		Milk, 1 c
Midafternoon snack	Milk, 1 c	Chicken sandwich
		Milk, 1 c
Dinner	Broiled steak	Broiled steak
	Steamed broccoli	Steamed broccoli with melted cheese
	Baked potato	Baked potato with sour cream
	Tomato salad with French dressing	Vegetable salad with French dressing
	Apple slices	Apple with peanut butter
		Milk, 1 c
Bedtime	Hot milk or cocoa,^† 1 c	Milk or cocoa,^† 1 c

^*Needs more kcalories, protein, and calcium.

^†For women with gestational diabetes, juice may be deemed inappropriate for control of blood glucose; oranges or other vitamin C–containing fruit may be advised later in the day rather than at breakfast, and desserts should be restricted based on values obtained from the woman’s self-monitoring of blood glucose levels (SMBG).

WHAT GENERAL NUTRITIONAL ADVICE IS RECOMMENDED DURING PREGNANCY?

WEIGHT GAIN

A major determinant of fetal outcome during pregnancy is maternal weight gain. Adequate weight gain improves fetal growth. A woman who is underweight before pregnancy may benefit with more weight gain than is typically recommended to best promote development of the placenta and vasculature needed to deliver nutrients to the fetus. However, excess weight gain needs to be avoided for the health of the mother and the growing fetus. The weight gain advised for overweight women is for the products of conception (Figure 11-1).

Debate continues on optimal weight gain. During the 1960s limits were set at 20 lb or less. In recent years the following amounts were felt to be the ideal weight gain:

• 25 to 35 lb for normal-weight women (body mass index [BMI] 20 to 26)

• 28 to 40 lb for an underweight woman (BMI < 20)

• 15 to 20 lb for an overweight woman (BMI > 26)

Average weight gain of about 1 lb per week in the second and third trimesters of pregnancy is expected. A grid can be used to plot weight gain throughout the pregnancy (Figure 11-2).

FIGURE 11-2 Recommended prenatal weight gain. Chart to monitor weight gain throughout pregnancy. *LMP,* Last menstrual period; *PGW,* pregestational weight (weight before conception). (From the New York State Health Department, WIC Program.)

However, current evidence is once again suggesting lower levels of weight gain during pregnancy are optimal. Evidence supports the Institute of Medicine (IOM) weight gain recommendation that will help to achieve better pregnancy outcomes in obese and overweight women (Jain and colleagues, 2007). Some distinctions with the new 2009 IOM guidelines are as follows:

• 28 to 40 lb for underweight women (BMI < 18.5)

• 25 to 35 lb gain for normal-weight women (BMI 18.5–24.9)

• 15 to 25 lb for overweight women (BMI 25–29.9)

• 11 to 20 lb for women with obesity (BMI ≥ 30)

Only about one third of U.S. women gain within IOM recommendations, with most far exceeding the goals (Olson, 2008). A large proportion of adolescents gain more than is recommended by the IOM. However, the use of adult BMI categories for determining weight gain in adolescent pregnancies may not be appropriate (Groth, 2007).

For multiple births increased weight gain is expected. One study of twins found the optimal rates of fetal growth and birth weights were associated with the maternal weight gains listed in Table 11-2 (Luke and colleagues, 2003).

Table 11-2

Prenatal Weight Gain Recommendations for Multiple Birth

WEIGHT CATEGORY	0-20 WEEKS (lb/wk)	20-28 WEEKS (lb/wk)	28-40 WEEKS (lb/wk)
Underweight
Normal weight			1
Overweight			1
Obesity

For triplet gestations a higher weight gain would be expected. A normal prepregnancy BMI and a total gestational weight gain of at least 35 to 45 lb are associated with fewer pregnancy complications (Eddib and colleagues, 2007).

Fact & Fallacy

FALLACY

Because a pregnant woman is “eating for two,” she should eat twice as much.

FACT

It should be remembered that the second person is very small—about 7 lb at birth. Although some nutrient requirements increase dramatically during pregnancy, the overall caloric need increases by only about 15%, amounting to about an extra 150 kcal/day during the first trimester and an additional 350 kcal/day for the remainder of the pregnancy, for a total of about 2200 to 2900 kcal. The additional kilocalories can easily come from extra milk, meat, and fruit (see Table 1-4). Individual guidance for kcalorie needs should be based on pregnancy weight gain and other parameters such as levels of blood glucose and ketones. Therefore it is important that a pregnant woman consume mainly nutrient-dense foods.

To promote a healthy diet, a pregnant woman should be encouraged to consume at least the minimum number of servings recommended by the 2005 Dietary Guidelines and the MyPyramid Food Guidance System (Table 11-3), with a focus on the use of whole grains and unprocessed or minimally processed foods. This equates to about 1500 kcal daily depending on choices. This is likely too few kcalories, but if weight goals are being met and there are no ketones (see section on diabetes), this level may be appropriate.

Table 11-3

Changes in Foods From the MyPyramid Food Groups During Pregnancy and Lactation

MYPYRAMID GROUPS*	NONPREGNANT WOMEN	PREGNANT WOMEN (SECOND HALF OF PREGNANCY)	LACTATING WOMEN
Milk
Adult	3 c or more	3 c or more	4 c or more
Adolescent	4 c or more	5 c or more	5 c or more
Vegetable and fruit
Citrus and other vitamin C foods	1 serving	2 servings	2-3 servings
Dark green, leafy or deep orange vegetable	1 serving at least every other day	1 serving daily	1-2 servings daily
Other fruits or vegetables, including potatoes^†	3-4 servings	2 servings	2 servings
Meat or alternate	2 servings or more	3 servings or more (6 oz cooked or more)	3 servings or more (6 oz cooked or more)
Cereal and bread, whole grains	6 servings or more	6 servings or more	6 servings or more

If fortified milk is not used, obtain physician’s instructions for vitamin D supplementation.

Use iodized salt.

Use water or other beverages—at least 6 to 8 c daily.

^*Additional servings of these or any other food may be added as needed to provide the necessary calories and palatability.

^†Total vegetable and fruit intake advised to be at least c daily.

HOW DOES NUTRITION INFLUENCE THE OUTCOME OF PREGNANCY?

PREGNANCY PLANNING

Good nutritional status for an optimal pregnancy outcome begins long before conception. Adequate growth and development (see Chapter 12) of the female child helps support reproductive health. Having adequate nutrient stores to allow for fetal growth and development is critical.

PREVENTION OF NEURAL TUBE DEFECTS

Neural tube defects (NTDs) are severe congenital malformations due to failure of neural tube formation in the first few weeks of pregnancy. This has been linked with folic acid deficiency. Because conception generally occurs days and weeks before its recognition, all women of childbearing years are advised to consume folic acid (0.4 to 1.0 mg/day), optimally from supplements, but also from foods naturally high in folic acid and fortified foods. Adequate intake of folic acid is advised through pregnancy, the postpartum period of 4 to 6 weeks, and through the duration of breastfeeding.

Neural tube defects include the condition spina bifida, in which the spinal canal does not fully close, and other congenital anomalies such as altered brain development, oral facial cleft, structural heart disease, limb defect, urinary tract anomaly, and hydrocephalus. There has been a decrease in the prevalence of cleft lip and cleft palate in the United States that coincided with the 1998 mandatory folic acid fortification of enriched cereal grains.

There is an increased need for folic acid supplementation with several health risks. This includes epilepsy, type 1 diabetes, class II or III obesity (see Chapter 6), family history of neural tube defect, and belonging to a high-risk ethnic group, such as the Sikh population. A higher intake also is advised for women with a history of poor compliance, variable diet, no consistent birth control, and substance use. The recommended intake for high-risk women is a multivitamin with 5 mg folic acid, beginning at least 3 months before conception and through the first semester of pregnancy. During the second and third trimesters of pregnancy, the postpartum period, and throughout breastfeeding 0.4 to 1.0 mg is advised (Wilson and colleagues, 2007).

Folate intake by women of childbearing age in the United States has decreased by approximately 130 mcg/day, after an earlier rise from food fortification. This is believed to be due to lower-carbohydrate diets and consequently less intake of fortified grain products. There are concerns of an increased incidence of neural tube defects, and recommendations have been made to consider the optimal means to fortify the food supply (Quinlivan and Gregory, 2007).

There may be other factors required to reduce the incidence of neural tube defects that are related to homocysteine. Adequate intake of vitamins B₁₂ and B₆ is advised for all women of reproductive age (Candito and colleagues, 2008). Without these B vitamins a number of biologic processes are affected as a result of suppressed methylation (addition of CH₃ to various body compounds). Due to its short half-life, vitamin B₆ is particularly important for undisturbed embryo (the term used for the fetus in the first trimester) development. It should be taken along with folic acid as a periconceptional supplement to prevent embryonic deformities (Weingärtner and colleagues, 2007). Vitamin B₁₂ deficiency, such as found with a vegan diet or among women with previous bariatric weight loss surgery, should be considered for infants with encephalopathies (degenerative diseases of the brain) that may be reversible if caught early (Gutiérrez-Aguilar and colleagues, 2005).

OBESITY

Obesity is an epidemic worldwide, and its adverse effects on conception, the health of the fetus, and lactation are now being recognized. Maternal risks of obesity during pregnancy include gestational diabetes, hypertension and preeclampsia (see later section), and increased incidence of delivery complications, whereas risks to the fetus include miscarriage, macrosomia, and stillbirth (Catalano, 2007). The ability to successfully breastfeed also is impaired with obesity. Increased efforts are likely required to promote the production and flow of breast milk with an obese woman. Women should ideally be counseled to prevent obesity or lose weight before conception.

Bariatric weight loss surgery is increasingly being advocated for women of childbearing years. This can help in some regards, but other adverse effects can occur with these procedures. Extremely obese persons often have nutritional deficiencies, particularly in fat-soluble vitamins, folic acid, and zinc. Bariatric surgery can worsen these deficiencies because of the severely reduced food portions and malabsorption in bypass procedures. Protein deficiency can develop that may require enteral or parenteral nutritional support (see Chapter 15). Anemia can develop from deficiency of iron, folic acid, and/or vitamin B₁₂. Wernicke encephalopathy from thiamin deficiency can develop that causes neurologic damage. A thorough nutritional follow-up should be performed before conception and during pregnancy after obesity surgery (Folope, Coëffier, and Déchelotte, 2007).

PREEXISTING DIABETES MANAGEMENT

Type 1 diabetes was once considered an automatic cause for alarm if pregnancy occurred. Even with long-standing diabetes, it is now believed that the outcome for mother and child is likely to be favorable if the various health concerns are managed well. It is now known that if a pregnant woman with diabetes maintains near normal blood glucose levels before conception and throughout the pregnancy, she is just as likely as a woman without diabetes to bear a healthy, normal infant.

It is paramount, however, that tight control over blood sugar levels be achieved before conception to help prevent birth defects from developing during the critical first trimester. For women with preexisting type 2 diabetes, the same precautions need to be taken. With uncontrolled type 2 diabetes, rates of perinatal mortality (25 per 1000) and congenital malformation (99 per 1000) are at least as poor as those in uncontrolled type 1 diabetes. The rates of hypertension, preeclampsia, cesarean birth, and postpartum hemorrhage are increased with uncontrolled type 2 diabetes (Dunne, 2005).

An added concern of women who are taking insulin to manage their diabetes is nighttime hypoglycemia. Lantus has not yet been approved for the management of diabetes because of its altered protein structure. Lantus would be the optimal long-acting insulin to use because it is peakless with low likelihood of hypoglycemia. Until Lantus is found to be safe to use during pregnancy, the other long-acting insulin, NPH, is advised. However, NPH does increase the risk of hypoglycemia, especially during the time of peak action, which is about 6 hours, with a variable range of peak action between 4 and 8 hours. It is for this reason that evening doses of long-acting insulin should be given at bedtime to allow for the peak action to occur closer to the time of the dawn phenomenon after 4 AM (refer to Chapter 8). An evening snack that includes carbohydrate is recommended for all women during pregnancy to decrease production of ketones, but such a snack will also help prevent nighttime hypoglycemia.

With the advent of insulin pump therapy increased numbers of women during pregnancy use this technology. With appropriate and educated use of insulin pumps, maintaining normal blood glucose levels is easier than provision of insulin by injection. However, risks still exist. In one study the rates of diabetic ketoacidosis (DKA) and neonatal hypoglycemia were significantly higher in the group using pump therapy (Chen and colleagues, 2007).

Neonatal hypoglycemia needs to be avoided as much as hyperglycemia. Maintaining normal glucose levels during fetal life depends entirely on continuous placental glucose transfer. If the maternal level of blood glucose is low, the placental transfer of glucose to the fetus will be low. A number of health concerns for the fetus can develop with exposure to hypoglycemia. One problem is seizures (Okanishi and colleagues, 2008). Hypoglycemia is linked with developmental delay and permanent brain damage. Intrauterine growth retardation and prematurity may also be a consequence of fetal hypoglycemia. Hyperglycemia during pregnancy causes the fetus to increase endogenous insulin production, which can lead to hypoglycemia when this high supply of glucose is stopped, such as at delivery, but also potentially in utero. The goal of treatment in infants with hyperinsulinemia is to prevent brain damage from hypoglycemia by maintaining plasma glucose at 70 mg/dL (Palladino, Bennett, and Stanley, 2008).

Control of pregnancy with diabetes is best handled with a medical team approach, so that the most appropriate plan and means of control are developed, including aspects such as insulin, diet, and home glucose monitoring. This includes the mother in making decisions regarding how to manage her blood glucose levels. Discussion should include the benefits of diabetes management during pregnancy. This has been shown to help compliance and outcomes with a group of educated women realizing good metabolic control (A_1c of 7.5%; see Chapter 8) as compared with a noneducated group (A_1c of 8.4%). Clinical outcomes noted in the group of educated women included control of retinopathy, milder cases of preeclampsia, and no perinatal deaths (Todorova, Mazneikova, and Ivanov, 2004). Although this study defined good control with an A_1c of 7.5%, most health care professionals advise an A_1c in the 5% range during pregnancy for optimal fetal outcomes.

There are different viewpoints on optimal maternal blood glucose levels. The American College of Obstetricians and Gynecologists (ACOG, 2005) goals are as follows:

• Less than or equal to 95 mg/dL fasting

• Less than or equal to 100 mg/dL preprandial

• Less than or equal to 140 mg/dL 1-hour postprandial

• Less than or equal to 120 mg/dL 2-hours postprandial

The American Diabetes Association (ADA, 2004) advises the following:

• 80 to 110 mg/dL preprandial

• Less than or equal to 155 mg/dL 2-hours postprandial

The higher values of the ADA reflect revised guidelines using the newer blood glucose meters that are calibrated to read the higher plasma levels in order to match laboratory values. High postprandial blood sugar levels may indicate a need for further carbohydrate restriction (particularly needed at breakfast), a need for insulin, or both. Morning urine ketone levels must also be monitored for a woman with GDM who is restricting her carbohydrate intake. Too little carbohydrate intake, too little insulin production, or weight loss of any amount can cause the mother’s body fat to break down excessively. The resulting ketone buildup is potentially detrimental to the growing fetus and needs to be corrected with increased carbohydrates especially at night, insulin, or both. On occasion, a middle-of-the-night carbohydrate snack may be necessary to stop the morning ketonuria; this is usually not a problem because ketonuria is most likely to occur in the third trimester when the mother is up in the night using the bathroom.

IMPACT OF SEASON

Development of certain conditions have been related to season of birth, including schizophrenia, multiple sclerosis, type 1 diabetes, and longevity. This may be influenced by seasonal variation in nutrient intake during pregnancy (Watson and McDonald, 2007). Significantly fewer adolescents living in Chicago who developed diabetes were born during October. This was especially true among males and those who apparently had developed type 2 diabetes (Grover, Lipton, and Sclove, 2004).

One nutrient that is influenced by season is vitamin D. This is certainly true in Northern climates, but there is evidence that subclinical vitamin D deficiency can occur, even in regions with a temperate climate at a latitude 39.5 degrees N (Cabezuelo and colleagues, 2007). Vitamin D deficiency in utero has been linked with craniotabes (soft bone tissue of the skull due to reduced mineralization) in otherwise normal neonates. The condition can persist at least until 1 month of age among breastfeeding infants (Yorifuji and colleagues, 2008).

ABILITY TO CONCEIVE

The mother’s nutrition and health status influences the growth and development of the fetus, but it can even affect the ability to conceive a pregnancy. Polycystic ovary syndrome (PCOS) is associated with reproductive dysfunction. Reversing obesity and insulin resistance has been shown to increase fertility without the need for costly assisted reproduction. In fact, women who undergo bariatric weight loss surgery often have unplanned pregnancies because of the increased fertility associated with achieving a more normal body weight.

INFLUENCING CONCEPTION

The quality of male sperm is now recognized as being important in achieving a healthy pregnancy outcome. Even moderate increases in blood lead content were found to be related to an increase in immature sperm concentration, and altered size of sperm (Telisman and colleagues, 2007). Cigarette smoking increases levels of both lead and cadmium in semen and leads to increased oxidative damage to sperm (Kiziler and colleagues, 2007).

Vitamin C has been linked with healthier sperm. A low level of seminal ascorbic acid is associated with DNA damage of sperm. An adequate intake of vitamin C helps prevent oxidative damage of sperm quality (Song, Norkus, and Lewis, 2006). The plasma ascorbic acid content of semen was found decreased in smokers and in infertile men. Beyond DNA damage of sperm, low vitamin C levels and smoking are related to low sperm count and motility (Mostafa and colleagues, 2006). As reviewed previously in the book, excess vitamin C is linked with increased oxidative damage. The conception of a healthy pregancy may be helped when men consume moderate amounts of a variety of vitamin C foods.

PREVENTION OF BIRTH DEFECTS

Good nutritional status begins before conception and can help prevent birth defects. Down syndrome may be influenced by maternal nutritional status. Children with Down syndrome have been noted to have abnormalities in the metabolism of vitamin B₆. Oxalate is a marker of pyridoxine deficiency and is elevated in the amniotic fluid of fetuses with Down syndrome (Baggot and colleagues, 2008).

Fact & Fallacy

FALLACY

You can safely avoid gaining too much weight during pregnancy by taking calcium supplements instead of drinking milk.

FACT

Milk provides more nutrients than just calcium. A calcium supplement will not give you the extra 30 g of protein found in the recommended 4 cups of milk. Vitamin B₂ and other nutrients, such as potassium, magnesium, phosphorus, vitamins A and D, and other trace elements, are found in milk as well. Low-fat or skim milk can be used by weight-conscious women.

WHAT ARE NUTRITIONAL CONCERNS THROUGHOUT THE TRIMESTERS OF PREGNANCY?

FIRST-TRIMESTER CONCERNS

Once a pregnancy has been successfully conceived, the first trimester is the critical period of pregnancy. This is the period during which the embryo develops (see Box 11-1). In this period all formation of organs occurs, such as that of the heart, brain, liver, and intestinal tract.

Anemia

Iron deficiency anemia may be evident at the start of pregnancy. This can be due to a variety of problems. For any woman during pregnancy, iron deficiency anemia may occur later during pregnancy when iron intake and stores do not meet increased demands. This is generally preventable and treatable by daily supplements of 30 to 60 mg of ferrous salts. For women who do not tolerate large doses of iron, 18 mg is the standard amount in multivitamin and mineral preparations. However, evidence suggests intolerance to iron supplements is due to tablet size, rather than the iron content (Nguyen and colleagues, 2008).

An increased intake of red meat and cereals fortified with iron (in combination with a vitamin C source) may be adequate to meet iron goals. Undertaking iron studies is advised if there is concern about iron deficiency anemia. This is, in part, due to potential for iron overload. Endometriosis, for example, appears to be adversely affected by iron overload (Defrère and colleagues, 2008).

A newer cause of anemia is related to bariatric weight loss surgery, which is increasingly being performed on women of childbearing years. Iron deficiency develops after gastric bypass for several reasons, including intolerance of red meat, diminished stomach secretions, and malabsorption with removal of portions of the small intestine. Oral iron supplementation and vitamin C in addition to a multivitamin should be prescribed for women of childbearing years who have had bariatric surgery. Monitoring is required because it may take years before anemia develops. Once iron deficiency has developed, parenteral iron or blood transfusions may be required (Love and Billett, 2008).

Other forms of anemia also may occur during pregnancy. Copper deficiency causes one form of anemia. Both iron and copper are essential micronutrients and are required for a wide variety of enzymatic and other processes within the developing fetus (McArdle and colleagues, 2008). Deficiency of vitamin B₁₂ or folic acid, both forms of macrocytic anemia, may be a cause. If vitamin B₁₂ deficiency is suspected during pregnancy, as with a woman following a vegan diet, urinary methylmalonic acid excretion and plasma homocysteine levels should be determined and vitamin B₁₂ supplementation should be started during pregnancy as needed and with the young infant to avoid potentially irreversible damage of the fetus and infant. One case of severe vitamin B₁₂ deficiency involved a 7-month-old infant who developed muscular weakness believed to be due to impaired myelination that was irreversible (Schlapbach and colleagues, 2007).

Morning Sickness

Nausea or morning sickness commonly occurs in the first trimester and for some women throughout the entire pregnancy. The cause of the nausea is not fully understood but is probably related to hormonal changes during pregnancy. Reduced motility throughout the gastrointestinal (GI) tract occurs, which is believed to allow for the increased absorption of nutrients. However, the reduced motility may also lead to feelings of fullness and nausea. Because high-fat foods further slow the movement of food through the GI tract, they should be avoided unless tolerated and appropriate for individual weight gain goals.

Preliminary evidence suggests ginger (Zingiber officinale) may be an effective and safe treatment for nausea and vomiting in pregnancy. Use of 650 mg of ginger or 25 mg of vitamin B₆ 3 times per day were both found to be effective for treatment of nausea and vomiting in pregnancy. However, ginger was more effective than vitamin B₆ (Chittumma, Kaewkiattikun, and Wiriyasiriwach, 2007). Doses needed for control of nausea and vomiting have not been specifically determined. One study found the dose of 1 g of ginger or 40 mg of vitamin B₆ daily were equally effective in reducing vomiting, and once again ginger was found to be more effective in controlling nausea (Ensiyeh and Sakineh, 2008).

Applied in daily doses of up to 6 g, fresh ginger root generally has few side effects (Betz and colleagues, 2005). The level of vitamin B₆ in treating nausea and vomiting is much higher than the DRI. The average dose of vitamin B₆ in one study, approximately 130 mg/day for a period of about 5 to 13 weeks, was associated with one major malformation, and the average birth weight was approximately 3000 to 4000 g (Shrim and colleagues, 2006). Long-term ingestion of vitamin B₆ greater than 100 mg/day is associated with neuropathy. The DRI for vitamin B₆ is 2.6 mcg during pregnancy, and the upper tolerable intake level (UL) has not been determined. Caution is advised.

An assessment of common provider advice for moderate to severe nausea with occasional vomiting includes the following:

• Eat frequent, small meals (93% of providers)

• Snack on soda crackers (68.5%)

• Take vitamin B₆ along with medication (67.1%) (Power, Milligan, and Schulkin, 2007)

The nausea of pregnancy may be related to low blood glucose levels. It is well known that the hormone glucagon can cause severe nausea, and this hormone is produced in response to lowering of blood glucose levels. It may be for this reason that the standard advice for women to eat dry toast or crackers before getting out of bed has been found helpful.

For a woman with morning sickness, a gradual increase in food consumption during the late afternoon and evening can replace nutrients that were not consumed in the morning. Including a bedtime carbohydrate snack with a protein source may help to stabilize blood sugar levels during the night and help prevent morning sickness.

Hyperemesis Gravidarum

Hyperemesis gravidarum, commonly referred to as simply hyperemesis, is characterized by excessive and prolonged vomiting beyond the first trimester. The severity of vomiting leads to significant weight loss, and the diagnosis includes a weight loss of over 5% with electrolyte imbalance. It is probably more common than statistics show because treatment may be in a physician’s office rather than in a hospital setting. The cause of hyperemesis is generally unknown, although various issues have been implicated, including hyperthyroidism, infection with Helicobacter pylori, and altered hormones. Hyperemesis can cause serious dehydration and vitamin deficiencies, such as thiamin deficiency, which causes signs and symptoms of beriberi and Wernicke’s encephalopathy (Indraccolo and colleagues, 2005).

Altered taste perception and aversion to smells of cooking food have been noted. It is partially for this reason that all foods that are tolerated are considered acceptable when severe nausea and vomiting are adversely affecting weight gain. Nutrient density becomes a minor issue when weight gain is paramount to combat the effects of hyperemesis. If a woman with hyperemesis can tolerate jelly beans or potato chips, they may be warranted as a source of concentrated kcalories to prevent further weight loss. Once the hyperemesis is resolved, more nutrient-dense foods can be included such as vegetables.

It is advised to check for ketones (see section on gestational diabetes) in order to determine management need (Sheehan, 2007). Control of ketones requires hydration and insulin, but with hyperemesis of pregnancy provision of carbohydrates also will be required. An assessment of treatment of women who had suffered with hyperemesis for at least 27 weeks revealed the most effective treatments included intravenous (IV) hydration, serotonin inhibitors, and parenteral nutrition (Goodwin and colleagues, 2008). However, parenteral nutrition (provision of nutrients directly into large veins; see Chapter 15) is not without risk. One study found peripherally inserted central catheter (PICC; see Chapter 15) line has the potential for greater complications, such as infection and clot formation, while providing no advantage over tube feeding (see Chapter 15) in the management of pregnancies with hyperemesis (Holmgren and colleagues, 2008).

Fact & Fallacy

FALLACY

Hyperemesis is psychologic in origin.

FACT

There is little evidence that hyperemesis is caused by psychologic problems; rather, it is more likely that it causes psychologic distress itself. Stronger evidence indicates that hormonal or other physical issues are the basis for the development of hyperemesis. Smells, odors, and motion have been known to precipitate nausea and vomiting.

Promoting Neurologic Development

On a positive note, the inclusion of omega-3 fatty acids is now recognized to promote the development of the neurologic system in utero and early infancy. The primary source of omega-3 fatty acids, fish, comes at the risk of mercury poisoning. Sources relatively low in mercury include salmon, followed by shrimp, as the prime sources of omega-3 fatty acids. The more popular tuna can be consumed for omega-3 fatty acids but poses a greater risk for mercury toxicity (Mahaffey, Clickner, and Jeffries, 2008). One debate is how much fish is enough to provide the benefits of the omega-3 fatty acids without being detrimental due to mercury content. Higher fish intake was found associated with better child cognitive test performance, but higher mercury levels with poorer test scores. Fish consumption of two servings or less per week was not associated with a benefit (Oken and colleagues, 2008).

The large ocean fish such as shark, swordfish, and marlin or lake fish often contain high amounts of mercury and should be avoided during pregnancy. The appropriate state health department can be contacted regarding advisories for specific lake fish that should be avoided. Generally, small fish such as sardines are less likely to have high levels of mercury or other toxic substances harmful to a growing fetus.

Certain nutrients have greater effects on brain development than do others. These include protein, energy, certain fats, iron, zinc, copper, iodine, selenium, vitamin A, choline, and folate. Deficiency of these nutrients during fetal development includes adverse effects on information processing, memory, autonomic nervous regulation, and motor coordination (Georgieff, 2007).

Adequate intake of the B vitamins during pregnancy is important to promote neurologic development of the fetus. A dietary deficiency of vitamin B₁ is a cause of nerve damage. Wernicke’s encephalopathy can occur with severe hyperemesis. Thiamin supplementation should be provided to women with prolonged vomiting in pregnancy, especially at the first indication of neurologic signs and symptoms (see Chapter 3) (Chiossi and colleagues, 2006). Optimally thiamin should be provided intravenously in such a situation. Vitamin B₁₂ deficiency in utero (and in infancy) causes growth retardation, impaired or regression of psychomotor development, muscular hypotonia, and brain atrophy (Lücke and colleagues, 2007).

During gestation there is a high demand for the B vitamin choline. Adult rats supplemented with choline during early gestation have improved memory performance throughout their life span, whereas prenatally choline-deficient rats have memory deficits (Kovacheva and colleagues, 2007). It has been demonstrated that choline has a lasting effect on brain and behavior of the rat offspring (Cheng and colleagues, 2008). In one case of depletion of plasma choline and a similar substance in a pregnant woman, low placental weight and low infant birth weight was noted. The cause of the choline depletion appeared related to medications used to treat her bipolar disorder (Gossell-Williams, Fletcher, and Zeisel, 2008). Another B vitamin, pyridoxine, affects development of the part of the brain related to the learning process and memory retention. Reduced intellect and altered behaviors may occur in children of women with pyridoxine deficiency during pregnancy. Deficiency of this vitamin is common among women who used anovulatory steroids before pregnancy (Krishna and Ramakrishna, 2004).

Neurologic development continues into the second trimester and throughout early infancy. For women with low intake of fish, a daily vitamin/mineral supplement containing 200 mg docosahexaenoic acid (DHA) appears appropriate. This level of DHA given beginning at the twenty-first week of gestation significantly raised maternal levels of DHA at both the thirty-seventh week and 3 weeks postpartum, with breast milk containing twice the level of DHA as for women without the supplement (Bergmann and colleagues, 2008).