Body Mass Index Calculator

Heart disease, diabetes, high blood pressure, and adverse pregnancy outcome are all linked to being overweight. Your body mass index (BMI) is one of the most accurate ways to determine when extra pounds translate into health risks. It is a measure which takes a person’s weight and height into account to gauge total body fat in adults. In general, a BMI of 25 to 29.9 is considered overweight, and a BMI of 30 or higher is considered obese. The higher your BMI, the greater your risk of developing additional health problems.

According to health experts, people who are overweight but have no other health risk factors (such as high cholesterol or high blood pressure) should eat healthier and exercise to keep from gaining additional weight. For people who are overweight and also have health risks, experts recommend actively trying to lose weight. Always be sure to consult your doctor or other health professional before beginning any exercise or weight-loss program, especially during pregnancy.

Weight Gain During Pregnancy

No single weight gain target meets the needs of all pregnant women as the optimal amount of weight gain varies with the woman's height, age, plans to breast feed, and whether she is delivering twins. There are however, a few generally accepted basic guidelines. Women who enter pregnancy at more than 120% of standard weight still have a required weight gain of 15–25 pounds at a rate of about 0.7 pounds per week. Women who are at ideal body weight and are not going to nurse have a target of gaining about 22 pounds overall at a rate of 0.8 pounds per week. Women who enter pregnancy between 90% and 110% of ideal body weight and plan to nurse have a target weight gain of between 25–35 pounds overall at a rate of 0.9 pounds per week during the second and third trimesters. Physically immature adolescents and women at less than 90% of ideal body weight have a target weight gain of 32 (or a range of 28–40) pounds at a rate of 1.1 pounds per week. Women who know they are going to have twins have a target weight gain of 40 (or a range of 35–45) pounds with a weekly rate of 1.4 pounds during the last 20 weeks of pregnancy.

Another way to determine the appropriate weight gain for pregnancy is by using the body mass index (BMI) calculator above. According to the standard set in 1990 by the Institute of Medicine of the National Academy of Sciences, a woman with a low BMI (less than 19.8) should gain a total of 27.5–39.7 pounds during pregnancy; a woman with a normal BMI (19.8–24) should gain a total of 25.4–35.3 pounds during pregnancy; and a woman with a high BMI (greater than 25–29.9) should gain a total of 15.4–25.4 pounds during pregnancy. Short women (less than five feet) should strive for gains at the lower end of the ranges. Obese women (BMI greater than 29.9) have a separate recommended target weight gain of about 13.2 pounds. 

The amount of weight gain during pregnancy varies considerably among women with good pregnancy outcomes, in fact, published studies suggest that only 30–40% of American women actually have weight gains within the recommended ranges. For that reason, weight gain alone is not likely to be a good screening tool for pregnancy complications. On the other hand, weight gains outside the recommended ranges are associated with twice as many poor pregnancy outcomes than are weight gains within the ranges. 

Weight loss programs are not generally recommended during pregnancy, however, it should be noted that being overweight while pregnant increases the incidence of various conditions in both the mother and the fetus, such as gestational diabetes and blood pressure problems. The risk is proportional to the amount of excess weight. Overweight women have a higher risk of cesarean deliveries and a higher incidence of anesthetic and post-operative complications in these deliveries. Poor responsiveness in the newborn, large head, and some birth defects are more frequent in infants of obese mothers. Maternal obesity also increases the risk of newborn death and infants of overweight mothers require admission into intensive care units more often than do infants of normal-weight mothers. Although there are risks associated with being overweight during pregnancy, dieting during pregnancy can seriously endanger the health of the fetus and is not recommended. 

Some women are concerned that the recommended weight gain will result in too much weight gain or more weight retention after the baby is born, but there is no evidence to support this concern.