PREGNANCY WEIGHT RETENTION IN MORBID-OBESITY

Recent hypotheses suggest that for women who develop morbid obesity, i ncreases in weight associated with pregnancy may represent a significa nt contribution to their obesity status. The effects of multiple pregn ancies on weight gain were studied in 96 morbidly obese women (<13.6 k g over ideal weight at ages 20-24 or before an earlier first pregnancy and currently >44.5 kg over ideal weight) and 115 random control wome n from the Utah population. Self-reported weights for each pregnancy i ncluded: prepregnancy, greatest during pregnancy, and 6 weeks followin g delivery, which were validated against available hospital records, M ean number of pregnancies in each group were similar (4.2 and 4.3), ra nging from 1 to 9. Mean current age was 46 and mean weight gain since ages 20-24 was 46.0 kg in the morbidly obese and 14.1 kg in controls. Regression of current weight on total number of pregnancies, adjusting for weight at ages 20-24, showed a 1.3 kg/pregnancy increase in curre nt weight (p=0.03) with no difference between groups (p=0.6). Weight g ain subsequent to the last pregnancy was not related to the number of pregnancies (p=0.2). Morbidly obese women gained more weight during pr egnancy than controls only for the first pregnancy, Gains were similar for all other pregnancies. Morbidly obese women had smaller weight lo sses after delivery than the controls, but these differences were not significant. For the first pregnancy, morbidly obese women had a net w eight retention that was 4.0 kg greater than the controls at 6 weeks p ost-partum and an average of 1.6 kg/pregnancy greater retention for th e remaining pregnancies. Pregnancy weight gains for each pregnancy sub sequent to the first pregnancy were constant. These findings suggest: 1) women who develop morbid obesity have slightly less weight loss aft er delivery and greater between-pregnancy weight gains than controls; 2) the number of pregnancies does not affect the amount of weight gain ed after the last pregnancy; and 3) while multiparity may augment weig ht gain in morbidly obese women, it is probably not a primary factor i n the later development of morbid obesity.