Weight Matters

Undernutrition and Overnutrition
During the childbearing years, a woman's weight can affect outcomes of pregnancy and have far-reaching effects on the woman's health as well. Women who are very thin or very short when they conceive are at increased risk for delivering an infant who has fetal growth restriction. This condition contributes strongly to the high prevalence of low birthweight (weight less than 2,500 g) in the developing world. About four million infants born this small die. Many of the surviving infants are at increased risk for cognitive and neurological deficits and other adverse health outcomes. In addition, low-birthweight infants are more likely to become small adults. This may reduce their work capacity, and among women, it increases the risk of delivering a low birthweight infant.

The prevalence of overweight and obesity is alarmingly high in many countries and increasing rapidly throughout much of the world—in industrialized and developing nations alike. Currently, for example, more than 40% of nonpregnant U.S. women ages 15 to 49 years are overweight or obese. The majority of girls and adolescents who are overweight or obese will become overweight or obese adults. Obesity before pregnancy increases women's risk during the entire life cycle. For example, obesity increases risks for infertility, maternal and fetal complications during pregnancy (including congenital malformations) and delivery. During the postpartum period, obesity may impair lactation performance and, later in life, increase risk of chronic diseases such as cardiovascular disease and Type II diabetes.

Key Messages
Healthy weight before and during pregnancy improves the likelihood of favorable reproductive outcomes. Measures that help women achieve a healthy weight include:

• Monitoring their body weight and taking corrective actions as needed over the entire reproductive cycle.
• Delaying the first pregnancy to permit full developmental maturation before the start of childbearing.
• Gaining the appropriate amount of weight during pregnancy.
• Continuing to be active during pregnancy and the postpartum period but avoiding activities that produce a sensation of extreme fatigue.
• Gradually losing weight through diet and physical activity during the postpartum period (if overweight or at risk for retention of excessive weight).

Recommendations

• Increase awareness that healthy weight throughout the life cycle improves the likelihood of good health, including favorable reproductive outcomes.
• In preparation for motherhood, assist girls, adolescents, and women to achieve and/or maintain a healthy weight. Aim to reduce the number of women who start pregnancy with a Body Mass Index (BMI) less than 18.5 kg/m2 or greater than 25 kg/m2.
• Where adolescent pregnancy is highly prevalent (especially among the underweight and overweight), aim to increase the average age at first pregnancy to permit full developmental maturation before the start of childbearing.
• Assist women to gain a healthy amount of weight during pregnancy.
• Help women to aim for a healthy weight following birth.

Strategies to support these recommendations include the development of policies, guidelines, strategies, programs, and materials to promote the importance of healthy weight for favorable reproductive outcomes. In addition, surveillance and evaluation systems should be developed to monitor weight and behavioral changes in diet and physical activity. Health care providers should also be trained in weight management issues.