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. The effect of weight loss in overweight, lactating women on the growth of their infants. Antenatal exercise and birthweight. Continuing regular exercise during pregnancy: effect of exercise volume on fetoplacental growth. A diet and physical activity intervention for preventing weight retention among Taiwanese childbearing women: a randomised controlled trial.
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. 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. Does strenuous antenatal exercise reduce birthweight? Does reducing maternal exercise increase birthweight? What to advise about exercise during pregnancy? We recruited 117 women who intended to exercise 5 or more times weekly during pregnancy to a study of whether reducing the amount of maternal exercise during pregnancy is associated with an increase in birthweight. Only 61/117 (52%) of women agreed to be randomised to either continue or to reduce (to 3 or fewer sessions of exercise weekly) their intended pregnancy exercise program. Most women who refused randomisation did not want to risk being asked to reduce their exercise during pregnancy. Within the randomised trial, there was no statistically significant difference between the mean birthweight of babies born to women who continued and those who reduced their intended exercise program. The high rate of refusal of randomisation limits the power of the study to find a difference in birthweight, limits the generalisability of the results and shows that many women intending to exercise at this level during pregnancy have an uncompromising attitude to exercise. The purpose of this study was to test the null hypothesis that the volume of exercise at different times during pregnancy has no effect on fetoplacental growth.
                Seventy-five women who exercised regularly were evaluated before pregnancy and randomly assigned at 8 weeks' gestation to one of 3 exercise regimens for the remainder of pregnancy. Primary outcome variables included placental growth rate, birth weight, and placental volume at term.
                The offspring of the women who were randomly assigned to a high volume of exercise in mid and late pregnancy were significantly lighter (3.39 kg vs 3.81 kg) and thinner (8.3% fat vs 12.1% fat) than those offspring born of women who were randomly assigned to reduce their exercise volume after the 20th week. Maternal weight gain, fresh placental volumes, and histomorphometric indices of placental function were greater in the high-low group.
                These data indicate that a high volume of moderate-intensity, weight-bearing exercise in mid and late pregnancy symmetrically reduces fetoplacental growth, whereas a reduction in exercise volume enhances fetoplacental growth with a proportionally greater increase in fat mass than in lean body mass. to examine the effect of individual counselling on diet and physical activity from pregnancy to six months post partum, or from birth to six months post partum, on weight retention among Taiwanese women.
                a randomised controlled trial assigned participants to two experimental groups [from pregnancy to six months post partum (EP) and from birth to six months post partum (EPP)] and one comparison group.
                a 3900-bed medical centre in northern Taiwan with around 3000 births annually.
                a sample of 189 women who had regular check-ups during pregnancy and gave birth at the medical centre.
                the comparison group received the routine outpatient department obstetric educational programme. The EP group attended regularly scheduled clinic visits with individualised dietary and physical activity education plans from 16 gestational weeks to six months post partum, and received on brochure. The EPP group received the same educational intervention as the EP group from 24-48 hours after birth to six months post partum.
                body weight, body mass index, health-promoting behaviour and psycho-social variables (self-efficacy, body image, depression and social support).
                average gestational weight gain was 14.02, 15.27 and 16.22 kg in the three EP, EPP and comparison groups respectively, and average weight retention at six months post partum was 2.34, 4.06 and 5.08 kg in the three groups, respectively.
                a diet and physical activity intervention from pregnancy is effective for reducing post-pregnancy weight retention.
                the findings of the present study should be taken into consideration when incorporating significant others and weight-loss maintenance strategies with interventions for a healthier family lifestyle.
                Copyright © 2009 Elsevier Ltd. All rights reserved.
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.]