also called PKU, is a rare inherited disorder that causes an amino acid called phenylalanine to build up in your body. PKU is caused by a defect in the gene that helps create the enzyme needed to break down phenylalanine.

Without the enzyme necessary to process phenylalanine, a dangerous buildup can develop when a person with PKU eats foods that are high in protein. This can eventually lead to serious health problems.

For the rest of their lives, people with PKU — babies, children and adults — need to follow a diet that limits phenylalanine, which is found mostly in foods that contain protein.

Babies in the United States and many other countries are screened for PKU soon after birth. Recognizing PKU right away can help prevent major health problems.

PKU symptoms can be mild or severe and may include:

• Intellectual disability (formerly called mental retardation)
• Delayed development
• Behavioral, emotional and social problems
• Psychiatric disorders
• Neurological problems that may include seizures
• Hyperactivity
• Poor bone strength
• Skin rashes (eczema)
• A musty odor in the child's breath, skin or urine, caused by too much phenylalanine in the body
• Fair skin and blue eyes, because phenylalanine cannot transform into melanin — the pigment responsible for hair and skin tone
• Abnormally small head (microcephaly)

Babies born to mothers with high phenylalanine levels don't often inherit PKU. However, they can have serious consequences if the level of phenylalanine is high in the mother's blood. Complications at birth may include:

• Intellectual disability
• Low birth weight
• Delayed development
• Abnormally small head
• Heart defects
• Behavioral problems

Testing your baby after birth

A PKU test is done a day or two after your baby's birth. The test isn't done before the baby is 24 hours old or before the baby has ingested some protein in the diet to ensure accurate results.

A nurse or lab technician collects a few drops of blood from your baby's heel or the bend in your baby's arm.

A laboratory tests the blood sample for certain metabolic disorders, including PKU.

If you don't deliver your baby in a hospital or are discharged soon after the birth, you may need to schedule a newborn screening with your pediatrician or family doctor.

If this test indicates your baby may have PKU:

Your baby may have additional tests to confirm the diagnosis, including more blood tests and urine tests

You and your baby may undergo genetic testing to identify gene mutations

• Nutrition assessment that includes appropriate weight for height and adequacy and quality of dietary intake and habits

• Diagnosis of nutrition-related problems or risk factors such as diabetes, phenylketonuria (PKU), and obesity

• Intervention based on an individual’s dietary goals and plan to promote appropriate weight gain, ingestion of a variety of foods, appropriate use of dietary supplements, and physical activity

• Evaluation as an integral part of the nursing care provided to women during the preconception period and pregnancy, with referral to a nutritionist or dietitian as necessary

are birth defects of the brain, spine, or spinal cord. They happen in the first month of pregnancy, often before a woman even knows that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In spina bifida, the fetal spinal column doesn't close completely.

Getting enough folic acid, a type of B vitamin, before and during pregnancy prevents most neural tube defects.

Neural tube defects are usually diagnosed before the infant is born, through lab or imaging tests. There is no cure for neural tube defects. The nerve damage and loss of function that are present at birth are usually permanent. However, a variety of treatments can sometimes prevent further damage and help with complications.

Anencephaly is a defect in the closure of the neural tube during fetal development. The neural tube is a narrow channel that folds and closes between the 3rd and 4th weeks of pregnancy to form the brain and spinal cord of the embryo. Anencephaly occurs when the "cephalic" or head end of the neural tube fails to close, resulting in the absence of a major portion of the brain, skull, and scalp. Infants with this disorder are born without a forebrain (the front part of the brain) and a cerebrum (the thinking and coordinating part of the brain). The remaining brain tissue is often exposed--not covered by bone or skin. A baby born with anencephaly is usually blind, deaf, unconscious, and unable to feel pain. Although some individuals with anencephaly may be born with a rudimentary brain stem, the lack of a functioning cerebrum permanently rules out the possibility of ever gaining consciousness. Reflex actions such as breathing and responses to sound or touch may occur.

The cause of anencephaly is unknown. Although it is thought that a mother's diet and vitamin intake may play a role, scientists believe that many other factors are also involved.

Recent studies have shown that the addition of folic acid (vitamin B9) to the diet of women of childbearing age may significantly reduce the incidence of neural tube defects. Therefore it is recommended that all women of childbearing age consume 0.4 mg of folic acid daily.

Foods Providing 500mcg or More per Serving

• Liver: chicken, turkey, goose (100g [3.5oz]) Foods Providing 200mcg or More per Serving

• Liver: lamb, beef, veal (100g [3.5oz]) 

Foods Providing 100mcg or More per Serving

• Legumes, cooked (½ cup)

• Peas: black-eyed, chickpea (garbanzo)

• Beans: black, kidney, pinto, red, navy

• Lentils

• Vegetables (½ cup)

• Asparagus

• Spinach, cooked

• Papaya (1 medium)

• Breakfast cereal, ready-to-eat ½ to 1 cup)

• Wheat germ (¼ cup)

Foods Providing 50mcg or More per Serving

• Vegetables (½ cup)

• Broccoli

• Beans: lima beans, baked beans, or pork and beans

• Greens: collards or mustard, cooked

• Spinach, raw

• Fruits (½ cup)

• Avocado

• Orange or orange juice

• Pasta, cooked (1 cup)

• Rice, cooked (1 cup)

Foods Providing 20mcg or More per Serving

• Bread (1 slice)

• Egg (1 large)

• Corn (½ cup)

• The uterine-placental-fetal unit.

• Maternal blood volume and constituents: During pregnancy, the total blood volume increases by about 40% to 50% over normal. The plasma volume increases by 50% in women in their first pregnancies and more than this in multifetal pregnancies. Although red blood cell (RBC) production also is stimulated, the expansion of RBC mass is not as great as that of plasma volume.

• Maternal mammary development.

A condition in which a baby doesn't grow to normal weight during pregnancy.

Both normal-weight and underweight women with inadequate weight gain have an increased risk for giving birth to an infant with intrauterine growth restriction.

• Progressive weight gain during pregnancy is essential to ensure normal fetal growth and development and the deposition of maternal stores that promote successful lactation.

• Recommended weight gain during pregnancy is determined largely by prepregnancy weight for height. The recommended total weight gain is as follows: underweight women, 12.5 to 18kg (28 to 40lbs); normalweight women, 11.5 to 16 kg (25 to 35lbs); overweight women, 7 to 11.5 kg (15 to 25lbs); and obese women 5 to 9╯kg (11 to 20lbs). For twin gestations, the recommended total weight gain is 21 to 28 kg (46 to 62lbs) for women who are underweight before conception, 17 to 25╯kg (37 to 54lbs) for normal-weight women, 14 to 23 kg (31 to 50lbs) for overweight women, and 11 to 19 kg (25 to 42lbs) for obese women.

• There is not enough information available to make firm recommendations about optimal weight gain for women with more than 2 fetuses, but provisional recommendations have been made for all prepregnancy body mass index (BMI) categories except the underweight category The provisional recommendations for a gestation with more than 2 fetuses suggest that normal-weight women gain 17 to 25 kg, overweight women gain 14 to 23 kg, and obese women gain 11 to 19 kg.

• Weight gain should be achieved through a balanced diet of regular foods chosen from all the different food groups.

• The pattern of weight gain is important: approximately 0.5 kg per week during the second and third trimesters for underweight women, 0.4 kg per week for normal-weight women, 0.3 kg per week for overweight women, and 0.2 kg per week for obese women.

Milk, meat, eggs, and cheese

Other valuable sources of protein are legumes, whole grains, and nuts.

8 to 10 glasses (2.3 L)

Foods in the diet should supply an additional 700 mL or more of fluid.

Dehydration may increase the risk for cramping, contractions, and preterm labor.

• Adolescence or less than 2 years postmenarche

• Frequent pregnancies: three within 2 years

• Poor fetal outcome in a previous pregnancy

• Poverty/food insecurity

• Poor diet habits with resistance to change

• Use of tobacco, alcohol, or drugs

• Weight at conception under or over normal weight

• Problems with weight gain

• Any weight loss

• Weight gain of less than 1 kg/month after the first trimester

• Weight gain of more than 3 kg/month after the first trimester

• Multifetal pregnancy

• Low hemoglobin and/or hematocrit values

• Diabetes

• Chronic illness, including an eating disorder, that affects intake, absorption, or metabolism of nutrients

Fish

• 3-oz can of sardines

• 4½-oz can of salmon (if bones

are eaten)

Beans and Legumes

• 3 cups of cooked dried beans

• 2½ cups of refried beans

• 2 cups of baked beans with

molasses

• 1 cup of tofu (calcium added in

processing)

Greens

• 1 cup of collards

• 1½ cups of kale or turnip

greens

Baked Products

• 3 pieces of cornbread

• 3 English muffins

• 4 slices of French toast

• 2 (7-inch diameter) waffles

Fruits

• 11 dried figs

• 1⅛ cups of orange juice with

calcium added

Sauces

• 3 oz of creamy pesto sauce

• 5 oz of cheese sauce

1000 mg daily for women 19 years and older

1300 mg for those younger than 19 years old

There is no increase in daily recommended intake during pregnancy

1.5 g/day to 2.3 g/day

Table salt is the richest source of sodium: 2.3 g/1 teaspoon

Malformations of the central nervous system in infants

When large amounts of iron and folic acid are consumed, the absorption of zinc is inhibited and the serum zinc levels are reduced as a result. Because iron and folic acid supplements are commonly prescribed during pregnancy, pregnant women should be encouraged to consume good sources of zinc daily. Women with anemia who receive high-dose iron supplements also need supplements of zinc and copper.

Is needed for protection against oxidative stress, and pregnancy is associated with increased oxidative stress.

Vegetable oils and nuts are especially good sources and whole grains and green leafy vegetables are moderate sources.

Is needed so that sufficient amounts of the vitamin can be stored in the fetus.

Deep yellow and deep green vegetables and fruits such as leafy greens, broccoli, carrots, cantaloupe, and apricots, provides sufficient amounts of carotenes that can be converted in the body to vitamin A.

Supplements are not recommended

• Improving the nutrition knowledge, meal planning, and selection and food preparation skills of young women

• Promoting access to prenatal care

• Developing nutrition interventions and educational programs that are effective with adolescents

• Striving to understand the factors that create barriers to change in the adolescent population

Is a normal finding in the third trimester of pregnancy

If it occurs in the first or second trimester, it could be related to calorie and protein deficiencies.

11 g/dL in the first and third trimester

10.5 g/dL in the second trimester

33% during the first and third trimester

32% during the second trimester

• A diet rich in vitamin C (in citrus fruits, tomatoes, melons, and strawberries) and heme iron (in meats) increases the absorption of iron supplement; therefore include these in the diet often.

• Bran, tea, coffee, milk, oxalates (in spinach and Swiss chard), and egg yolk decrease iron absorption. Avoid consuming them at the same time as the supplement.

• Iron is absorbed best if it is taken when the stomach is empty; that is, take it between meals with a beverage other than tea, coffee, or milk.

• Iron can be taken at bedtime if abdominal discomfort occurs when it is taken between meals.

• If an iron dose is missed, take it as soon as it is remembered if that is within 13 hours of the scheduled dose. Do not double up on the dose.

• Keep the supplement in a childproof container and out of the reach of any children in the household.

• The iron may cause stools to be black or dark green.

• Constipation is common with iron supplementation. A diet high in fiber with adequate fluid intake is recommended.

• Antiemetic medications, vitamin B6, ginger, and P6 acupressure may be effective in reducing the severity of nausea, although the evidence supporting them is not strong.

• Eat dry, starchy foods such as dry toast, melba toast, or crackers on awakening in the morning and at other times when nausea occurs.

• Avoid consuming excessive amounts of fluids early in the day or when nauseated (but compensate by drinking fluids at other times).

• Eat small amounts frequently (every 2 to 3 hours), and avoid large meals that distend the stomach.

• Avoid skipping meals and thus becoming extremely hungry, which may worsen nausea. Have a snack such as cereal with milk, a small sandwich, or yogurt before bedtime.

• Avoid sudden movements. Get out of bed slowly.

• Decrease intake of fried and other fatty foods. Try high-carbohydrate foods such as toast, rice, or potatoes. Some women find high-protein meals or snacks helpful.

• Breathe fresh air to help relieve nausea. Keep the environment well ventilated (e.g., open a window), go for a walk outside, or decrease cooking odors by using an exhaust fan.

• Eat foods served at cool temperatures and foods that give off little aroma. Avoid spicy foods.

• Avoid brushing teeth immediately after eating.

• Try salty and tart foods (e.g., potato chips and lemonade) during periods of nausea. Sucking a lemon slice may help.

• Try herbal teas such as those made with raspberry leaf or peppermint to decrease nausea.

A severe type of nausea during pregnancy.

Hyperemesis gravidarum, or severe and persistent vomiting causing weight loss, dehydration, and electrolyte abnormalities, occurs in up to 1% of pregnant women. Intravenous fluid and electrolyte replacement, enteral tube feeding, and in some instances total parenteral nutrition have been used to nourish women with hyperemesis gravidarum.

Vitamin B₁₂ which can result in megaloblastic anemia, glossitis (beefy red tongue), and neurologic deficits in the mother. 

However, this diet provides all the essential amino acids needed.