Weight Gain in Pregnancy

Weight gain guidelines for pregnant women are dictated primarily by the woman’s prepregnancy BMI. Weight gain guidelines are outlined in Table 1.1 [3]. These recommended weight gain ranges apply to all women irrespective of height, and racial or ethnic group.

In addition to total weight gain, the pattern of weight gain is also important and the IOM has indicated appropriate rates of weight gain during the second and third trimesters as summarized in Table 1.1. Any sudden and drastic gain in weight should be investigated carefully, as this may indicate fluid retention and possible hypertension.

Energy and Macronutrient Needs During Pregnancy

Calorie needs during pregnancy are not increased in the first trimester, but are increased by 340 kcal/ day in the second trimester and by 450 kcal/day in the third trimester. Individuals who engage in little physical activity may need less, and the converse is true for individuals who are very active. The best way to assess whether caloric intake is sufficient is by monitoring weight gain.

Protein needs are increased by approximately 25 g/day, for a total of 71 g/day. Protein-rich foods include lean meat, poultry, fish (some fish should be limited or avoided during pregnancy as described below), eggs, beans, nuts, and peanut butter. Protein supplements, such as high-protein drinks, are not recommended.

Approximately 175 g/day of carbohydrate is required during pregnancy. Again, this amount is adequately provided by a healthy diet, and most women have no difficulty achieving this. Carbohydrate is necessary to provide energy to the fetal brain and to spare protein for tissue growth. Some women who have adopted very low-carbohydrate diets should be counseled on the importance of including complex carbohydrates in their meals and snacks as the safety of low-carbohydrate diets during pregnancy has not been established.

Essential fatty acids (n-3 and n-6 fatty acids) are required for proper development of the fetal central nervous system. Good sources of these fats include vegetable oils, seeds, nuts, and fish. Several research studies have shown a clear positive association between fish intake during pregnancy and indicators of neurodevelopment of the child, including cognition and visual acuity [7, 8]; however, evidence from RCTs is inconclusive [9].

Table 1.2 Recommended dietary allowance (RDA) and adequate intake (AI) for selected nutrients in pregnancy

Life stage

RDA folate (pg/day)

RDA vitamin D(pg/day)

RDA vitamin A(pg/day)

RDA vitamin B12 (pg/day)

RDA iron (mg/day)

RDA calcium (mg/day)

Pregnancy, 14-18 years

600

15

750

2.6

27

1300

Pregnancy, 19-30 years

600

15

770

2.6

27

1000

Pregnancy, 31-50 years

600

15

770

2.6

27

1000

Lactation, 14-18 years

500

15

1200

2.8

10

1300

Lactation, 19-30 years

500

15

1300

2.8

9

1000

Lactation, 31-50 years

500

15

1300

2.8

9

1000

Source of information: Refs. [10, 11]

Although fish are the richest source of n-3 fatty acids, intake of some fish should be limited, and some fish should be avoided, during pregnancy due to concerns about mercury, as discussed below.

Fluid needs during pregnancy are generally accommodated for in response to increased levels of thirst. Water, milk, and unsweetened beverages are the best choices for hydration.

 
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