[Weight-control behaviors during pregnancy and their association with pre-pregnancy dieting experiences]

Objectives　Few studies have examined the weight-loss behaviors (i.e., dieting behaviors) among pregnant women who were not obese before pregnancy or explored the association between dieting behaviors during pregnancy and previous dieting experiences. Therefore, in this study, we aimed to identify the weight-loss behaviors practiced by pregnant women during pregnancy and to examine their associations with adherence to gestational weight gain guidelines of the Japan Society of Obstetrics and Gynecology, and as well as with past dieting behaviors.Methods　We included 601 pregnant women from Takatsuki City, Osaka Prefecture, Japan. After excluding participants with missing questionnaire responses, 529 participants were analyzed. Participants completed self-administered questionnaires during antenatal and one-month postpartum health examinations. Information regarding dieting behaviors during adolescence, the year before pregnancy, and pregnancy, including gestational weight gain, was collected. For the 496 participants with recorded pregnancy weight gain values, the odds ratios for achieving the recommended weight gain were calculated for "appropriate" and "inappropriate dieting behaviors." Furthermore, logistic regression analysis was used to calculate age- and pre-pregnancy body mass index-adjusted odds ratios (95% confidence intervals) for participants who engaged in dieting behaviors during their teenage years and the year before pregnancy and who subsequently engaged in "dietary restriction" or "inappropriate behaviors" during pregnancy.Results　Of all participants, 39.9% engaged in dieting behaviors during pregnancy. Among pregnant women with available gestational weight gain data, 33.5% achieved the recommended weight gain, whereas only 18.8% of women who were underweight before pregnancy met the guideline. The adjusted odds ratio for achieving weight gain compared to no dieting behavior was 1.0 (0.6-1.5) for "appropriate behaviors" and 1.0 (0.5-2.0) for "inappropriate behaviors," showing no significant association in either case. "Dietary restriction" during pregnancy and "inappropriate behaviors" were associated with "dietary restriction" in the year before pregnancy [6.4 (3.2-12.6), 6.1 (3.1-12.0)] and "inappropriate dieting" [6.0 (3.1-11.7), 6.4 (3.3-12.3)].Conclusions　Approximately 40% of non-obese pregnant women engaged in dieting behaviors during pregnancy. Moreover, those who engaged in "dietary restriction" or "inappropriate behaviors" in the year before pregnancy may continue such behaviors during pregnancy. Thus, antenatal checkups and nutritional guidance are required for guiding appropriate weight gain and screening previous dieting experiences. Furthermore, preconception care is necessary to ensure appropriate weight management.