Intervening to Prevent Postpartum Weight Gain

One approach to preventing weight gain is to identify times when individuals are at greatest risk of gaining weight, and to intervene. For women, pregnancy and the year afterward is a particularly risky time for weight gain. In one study, 40% to 50% of severely obese women reported that their weight problems began during previous pregnancies (Int J Obes 14:159, 1990).

Dr. Rena R. Wing and a team of University of Pittsburgh researchers found that behavioral weight loss intervention using group discussions, instruction on self-monitoring, and telephone follow-up was effective in helping women lose pregnancy-related weight (Int J Obesity 22:1103, 1998).

Treatment and control groups

Ninety new mothers were randomly assigned to 1 of 2 groups. The first group (n=43), which acted as controls, received an informational brochure about healthy eating and exercise (former Surgeon General C. Everett Koop’s On Your way to Fitness), and were assessed before the study began and 6 months later. The second group (n=47) entered a correspondence behavioral weight loss program that focused on low-fat, low-calorie meals and increasing physical activity. The second group attended 2 group sessions, and received 16 written lessons about nutrition, exercise, and changing behavior, and telephone follow-up contacts. The women were asked to keep a diary to monitor their weight loss and to return their records by mail.

Six months later

Among those who completed the program, the correspondence group lost significantly more weight during the 6-month treatment program than the control group: a mean of 7.8 kg (79% of their excess weight) vs. 4.9 kg. (44% of excess weight). The treatment group also lost a greater percentage of their pretreatment body weight than the control group: 10% vs. 5.8%. More than twice as many women in the correspondence group returned to their prepregnancy weights (33% vs. 11.5% of the control group).

According to Dr. Wing, the key to successful intervention might have been the fact that women were encouraged to use self-monitoring and had feedback on their diaries. There was no relationship between the number of phone contacts and weight loss. In addition, although the women were encouraged to reduce their fat intake to 20% of daily calories, they only reduced this to 30%.

Some difficulties of intervening in the postpartum period

Along with the successes came a few negatives; for example, 27% percent of the women dropped out of the program. Most of these dropouts were heavier at the start of the study and retained more of their pregnancy-related weight gain than women who completed the program. The reasons for dropping out were unknown, but the authors noted that a possible explanation was that participating in a weight-loss program was too big a burden for new mothers. Even those who stayed in the program were unable to increase their physical activity levels in spite of the emphasis on activity in the program. This also suggested that it was difficult for the new mothers to make behavioral changes. Five of the women became pregnant again, and only a third returned to their prepregnancy weight. Since the strongest predictor of return to prepregnancy weight was the amount of weight retained at pretreatment, the 6-month program may have been too short, according to the authors.