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Am Fam Physician. 2020;102(7):420-426

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For many patients, pregnancy is a highly anticipated and exciting phase of life, but it can also be anxiety provoking. Family physicians can resolve some of this anxiety and promote maternal and fetal health by making specific recommendations at prenatal visits. A daily prenatal vitamin with at least 400 mcg of folic acid and 30 mg of elemental iron should be recommended to promote neurologic and musculoskeletal fetal development. Weight gain in pregnancy should be guided by preconception body mass index. People who are underweight should gain 28 to 40 lb, those who have a normal weight should gain 25 to 35 lb, and those who are overweight or obese should gain 15 to 25 lb or 11 to 20 lb, respectively. A well-balanced diet including omega-3 fatty acids should be encouraged. Unpasteurized foods should be avoided during pregnancy because of the risk of listeriosis. Caffeine intake should be limited to 200 mg per day (about two small cups of coffee), and artificial sweeteners should be avoided. Pregnant patients should be encouraged to engage in regular cardiovascular activity for at least 150 minutes per week. Bed rest is not recommended. Sex can be continued throughout an uncomplicated pregnancy. Avoidance of alcohol and marijuana is recommended. The effects of hair dye or hair straightening products on fetal development or neonatal outcomes are unclear.

In 2016, prenatal care was initiated in the first trimester in more than 75% of pregnancies,1 providing a multitude of opportunities for family physicians to counsel these patients on the basics of a healthy pregnancy. During prenatal visits, physicians can dispel many myths about pregnancy. This article will discuss physical activity, provide recommendations for weight gain during pregnancy, review components of a well-balanced diet, discuss supplement and medication use, and dispel myths related to topics that have traditionally been taboo: sex and the use of marijuana and alcohol during pregnancy. Communicating this information in an individualized manner will promote maternal and fetal health.

Clinical recommendationEvidence ratingComments
Weight gain during pregnancy should be individualized based on prepregnancy body mass index.26 CSystematic review, cohort study, and guidelines showing that early weight gain and maternal obesity are associated with higher infant mortality
Unpasteurized foods should not be consumed during pregnancy.7,8 CPractice recommendations and analysis showing poor neonatal outcomes in patients with listeriosis
A prenatal vitamin with folic acid, vitamin D, calcium, and iron should be recommended for pregnant patients.1,3,4,9 AMeta-analyses and systematic reviews showing decreased fetal neural tube defects and promotion of musculoskeletal development
Instead of routinely being given a fish oil supplement, pregnant patients should be encouraged to consume two or three servings per week of fish that contains low levels of mercury.3,11 BRandomized controlled trials showing that high fish consumption decreases preterm birth, observational studies showing increased neurodevelopment in children, and expert opinion/usual practice
Pregnant patients should be encouraged to engage in moderate-intensity exercise for at least 150 minutes per week.15,16,19,20 BSystematic review and meta-analyses showing fewer newborn complications and maternal health benefits
Alcohol should not be consumed during pregnancy.36,37 CCase-control study showing risk of fetal alcohol spectrum disorder and lower birth weight
Caffeine intake should be limited to 200 mg per day during pregnancy.41,42 AMeta-analyses showing increased early pregnancy loss with high doses of caffeine
RecommendationSponsoring organization
Do not place patients, even those at high risk, on activity restriction to prevent preterm birth.Society for Maternal-Fetal Medicine
Do not routinely recommend activity restriction or bed rest during pregnancy for any indication.American College of Obstetricians and Gynecologists

Weight Gain and Diet

The National Academy of Medicine recommends that weight gain during pregnancy be based on preconception body mass index(Table 1).2 Patients should be counseled that pregnancy does not require doubling caloric intake.2 Weight goals should be individualized according to the baseline fitness level, prepregnancy weight, and other metabolic considerations. A safe recommendation is 350 to 450 calories per day above the previous intake3 (e.g., two slices of bread with half an avocado, ¾ cup of Greek yogurt or 1 cup of blueberries with two hard-boiled eggs). These recommendations optimize birth weight and minimize adverse pregnancy outcomes.2,4 Excessive weight gain and preexisting maternal obesity are associated with increased antepartum complications, including fetal death, stillbirth, and neonatal death5,6 (Table 25 ).

Prepregnancy body mass index (kg per m2)CategoryRecommended weight gain
< 18.5Underweight28 to 40 lb (12.7 to 18.1 kg)
18.5 to 24.9Normal weight25 to 35 lb (11.3 to 15.9 kg)
25.0 to 29.9Overweight15 to 25 lb (6.8 to 11.3 kg)
≥ 30Obese11 to 20 lb (5.0 to 9.1 kg)
RiskAbsolute risk per 10,000 pregnancies (95% CI)

Maternal BMI = 20 kg per m2 Maternal BMI = 25 kg per m2 Maternal BMI = 30 kg per m2
Fetal death7682 (76 to 88)102 (93 to 112)
Stillbirth4048 (46 to 51)59 (55 to 63)
Perinatal death6673 (67 to 81)86 (76 to 98)
Neonatal death2021 (19 to 23)24 (22 to 27)
Infant death3337 (34 to 39)43 (40 to 47)

When advising pregnant patients about their diet, physicians should counsel about foods to limit or avoid. Foods such as soft cheeses made from unpasteurized milk, deli meats, sprouts, melons not eaten immediately after cutting, and raw or smoked fish can be contaminated with Listeria monocytogenes. The risk of listeriosis is 18 times higher in patients who are pregnant compared with the general population.7 Other unpasteurized foods such as kefir, kombucha, and kimchi are less well studied. The Centers for Disease Control and Prevention recommends that all unpasteurized foods be avoided during pregnancy to prevent listeriosis.8 The mortality rate of fetal listeriosis is 25% to 35%, depending on the gestational age at the time of infection.7

Vitamins and Supplements

A well-balanced diet rich in vitamin D, folic acid, iron, calcium, omega-3 fatty acids, and other micronutrients should be encouraged for pregnant patients (Table 33,914 ). Prenatal vitamins are recommended because they provide folic acid, iron, calcium, and vitamin D. Ideally, they should be started before conception and should contain at least 400 mcg of folic acid,2,3 30 mg of elemental iron,2,3 200 to 300 mg of calcium,4 and 400 IU of vitamin D.4 Because of the role that vitamin D plays in bone development, the daily recommended intake for patients of childbearing age is 600 IU.9 Vitamin D can be obtained from fortified cereals, pasta, breads, cow's milk, cheese, and yogurt.9 Salmon and eggs are also excellent sources.9 Vitamin D can be synthesized in the skin when exposed to sunlight.9

MicronutrientRecommended daily intakeCommon amount in prenatal vitamins
Calcium1,000 mg200 to 300 mg
Elemental iron30 mg27 mg
Folic acid400 to 1,000 mcg*600 mcg
Omega-3 fatty acids650 mg0 to 450 mg
Vitamin D600 IU200 to 600 IU

Calcium is an important part of the prenatal diet. The recommended daily intake is 1,000 mg for people 19 years and older and 1,300 mg for those 14 to 18 years of age.9 Calcium can be obtained from milk and other dairy sources, and it is present in lower concentrations in dark green leafy vegetables.

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