The effect of weight loss in overweight, lactating women on the growth of their infants. A randomized study of the effects of aerobic exercise by lactating women on breast-milk volume and composition. Randomized trial of the short-term effects of dieting compared with dieting plus aerobic exercise on lactation performance. Structured diet and physical activity prevent postpartum weight retention. Reducing postpartum weight retention through a correspondence intervention. The effects of exercise and social support on mothers reporting depressive symptoms: a pilot randomized controlled trial.
The retention of weight gained during pregnancy may contribute to obesity. Lactation should promote weight loss, but weight loss is highly variable among lactating women. The risks associated with the restriction of energy intake during lactation have not been adequately evaluated. The purpose of this study was to determine whether weight loss by women during lactation affects the growth of their infants.
                We randomly assigned 40 breast-feeding women who were overweight (defined as a body-mass index [the weight in kilograms divided by the square of the height in meters] of 25 to 30) at 4 weeks post partum either to restrict their energy intake by 500 kcal per day and to exercise for 45 minutes per day for 4 days per week (the diet-and-exercise group) or to maintain their usual dietary intake and not exercise more than once per week for 10 weeks (the control group). We measured the weight and fat mass of the women and the weight and length of the infants before, during, and at the end of the study period.
                The mean (+/-SD) energy intake decreased by 544+/-471 kcal per day in the diet-and-exercise group. As compared with the control group, the women in the diet-and-exercise group lost more weight (4.8+/-1.7 kg vs. 0.8+/-2.3 kg, P<0.001) and fat mass (4.0+/-2.0 kg vs. 0.3+/-1.8 kg, P<0.001). The gains in weight and length of the infants whose mothers were in the diet-and-exercise group (1925+/-500 g and 7.8+/-2.0 cm, respectively) were not significantly different from those of the infants whose mothers were in the control group (1861+/-576 g and 7.3+/-1.7 cm).
                Weight loss of approximately 0.5 kg per week between 4 and 14 weeks post partum in overweight women who are exclusively breast-feeding does not affect the growth of their infants. The potential risks and benefits of regular exercise during lactation have not been adequately evaluated. We investigated whether regular aerobic exercise had any effects on the volume or composition of breast milk.
                Six to eight weeks post partum, 33 sedentary women whose infants were being exclusively breast-fed were randomly assigned to an exercise group (18 women) or a control group (15 women). The exercise program consisted of supervised aerobic exercise (at a level of 60 to 70 percent of the heart-rate reserve) for 45 minutes per day, 5 days per week, for 12 weeks. Energy expenditure, dietary intake, body composition, and the volume and composition of breast milk were assessed at 6 to 8, 12 to 14, and 18 to 20 weeks post partum. Maximal oxygen uptake and the plasma prolactin response to nursing were assessed at 6 to 8 and 18 to 20 weeks.
                The women in the exercise group expended about 400 kcal per day during the exercise sessions but compensated for this energy expenditure with a higher energy intake than that recorded by the control women (mean [+/- SD], intake, 2497 +/- 436 vs. 2168 +/- 328 kcal per day at 18 to 20 weeks; P < 0.05). Maximal oxygen uptake increased by 25 percent in the exercising women but by only 5 percent in the control women (P < 0.001). There were no significant differences between the two groups in maternal body weight or fat loss, the volume or composition of the breast milk, the infant weight gain, or maternal prolactin levels during the 12-week study.
                In this study, aerobic exercise performed four or five times per week beginning six to eight weeks post partum had no adverse effect on lactation and significantly improved the cardiovascular fitness of the mothers. Limiting postpartum weight retention is important for preventing adult obesity, but the effect of weight loss on lactation has not been studied adequately.
                We evaluated whether weight loss by dieting, with or without aerobic exercise, adversely affects lactation performance.
                At 12+/-4 wk postpartum, exclusively breast-feeding women were randomly assigned for 11 d to a diet group (35% energy deficit; n = 22), a diet plus exercise group (35% net energy deficit; n = 22), or a control group (n = 23). Milk volume, composition, and energy output; maternal weight, body composition, and plasma prolactin concentration; and infant weight were measured before and after the intervention.
                Weight loss averaged 1.9, 1.6, and 0.2 kg in the diet, diet + exercise, and control groups, respectively (P < 0.0001) and was composed of 67% fat in the diet group and nearly 100% fat in the diet + exercise group. Change in milk volume, composition, and energy output and infant weight did not differ significantly among groups. However, there was a significant interaction between group and baseline percentage body fat: in the diet group only, milk energy output increased in fatter women and decreased in leaner women. The plasma prolactin concentration was higher in the diet and diet + exercise groups than in the control group.
                Short-term weight loss (approximately 1 kg/wk) through a combination of dieting and aerobic exercise appears safe for breast-feeding mothers and is preferable to weight loss achieved primarily by dieting because the latter reduces maternal lean body mass. Longer-term studies are needed to confirm these findings. Postpregnancy weight retention contributes to the near-epidemic prevalence of obesity in the United States. This study examines the impact of an individualized, structured diet and physical activity intervention on weight loss in overweight women during the first year postpartum.
                Forty overweight postpartum women were randomized to either a structured (STR) or a self-directed (SELF) intervention. Measurements included body weight, percent body fat, daily caloric intake, habitual physical activity, and cardiorespiratory fitness. Subjects in STR received individualized diet and physical activity prescriptions derived from baseline measurements. They met weekly for the first 12 weeks and kept daily food and activity diaries. Subjects in SELF received a single 1-hour educational session about diet and activity.
                Only 23 of 40 participants remained in the study at 1 year postpartum. Of those, STR (n = 13) had a significant weight loss (7.3 kg, p < 0.01), a significant decrease in percent body fat (6%, p < 0.01), and no change in fat-free mass. SELF (n = 10) had no significant change in weight, percent body fat, or fat-free mass.
                Women who committed to this one class per week for 12 weeks postpartum had a high likelihood of successful weight loss that persisted at 1 year. Women who were overweight before pregnancy were unlikely to lose the pregnancy-related weight without the help of a formal intervention. This suggests that healthcare professionals should strongly encourage postpartum women to enroll in a structured diet and exercise program. Since post-pregnancy weight retention may contribute to the development of obesity, we sought to determine whether a behavioral weight loss intervention was effective in returning women to their pre-pregnancy weight.
                Ninety women who had given birth in the past 3-12 months and whose weight exceeded their pre-pregnancy weight by at least 6.8 kg were randomly assigned to either: a) a six-month behavioral weight loss intervention, delivered via correspondence or b) a no-treatment control group. Assessments of body weight, physical activity and eating patterns were conducted at pre-treatment and six months (post-treatment).
                During the six month treatment, subjects in the correspondence condition lost significantly more weight than control subjects (7.8 kg vs 4.9 kg, P = 0.03) and lost a greater percentage of their excess postpartum weight (79% vs 44%, P = 0.01). Furthermore, a significantly greater percentage of correspondence subjects than controls returned to their pre-pregnancy weight (33% vs 11.5%, P < 0.05). Weight loss in the correspondence group was correlated with completion of self-monitoring records (r = 0.50, P < 0.005).
                A behavioral weight loss intervention, delivered via correspondence, appears to be effective in reducing women's postpartum weight retention. Future studies should examine the acceptability and the long-term impact of a correspondence postpartum weight loss intervention. A 12-week randomized controlled trial was conducted (n = 20) investigating the effects of a multi-intervention programme of exercise and social support compared to a control group. Both groups had given birth in the past 12 months and were experiencing depressive symptomatology. Pretest data of physical fitness and structured questionnaires were compared to post-test data. The results from the study showed that mothers who were in the multi-intervention group improved their fitness levels and depressive symptomatology significantly more than the control group. However, there were no significant changes to either group's social support levels. These results are encouraging and suggest that a pram push walking intervention might be an effective treatment for mothers suffering postnatal distress.
Preliminary evidence from this review suggests that both diet and exercise together and diet alone help women to lose weight after childbirth. Nevertheless, it may be preferable to lose weight through a combination of diet and exercise as this improves maternal cardiorespiratory fitness and preserves fat-free mass, while diet alone reduces fat-free mass. This needs confirmation in large trials. For women who are breastfeeding, more evidence is required to confirm whether diet or exercise, or both, is not detrimental for either mother or baby.
[Note: The 23 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]