Effects of dieting and physical activity on pregnancy and lactation.

Concerns regarding weight control and fitness during the reproductive years have prompted questions about dieting and physical activity among pregnant and lactating women. Dieting to lose weight is never recommended during pregnancy, even among obese women. Once lactation is established, moderate energy restriction to achieve a weight loss of < or = 2 kg/mo is probably safe for women who are overweight initially. There are several potential risks and benefits of exercise during pregnancy and lactation. The data available indicate that moderate aerobic exercise is safe and beneficial for most women, if appropriate guidelines are followed.