Background: Maternal obesity is known to adversely impact both time to conception and pregnancy outcomes. Some data suggests modest weight loss achieved with lifestyle modification reduces time to conception but does not alter pregnancy outcomes. Bariatric surgery alters pregnancy outcomes, but guidelines suggest delaying conception 18-24 months after surgery. We have compared ‘time to conception’ in obese women after a lifestyle modification (standard care) and after a VLED program.
Methods/design: A two-arm, parallel group, randomized control trial, was conducted at the University of Melbourne. Women (n=164) aged 18-38 years, with a BMI 30-55kg/m2, who planned to conceive in the next 6-12 months were randomized to one of two 12-week interventions. Group A aimed for modest weight loss (MWL ≤3% body weight) using a hypocaloric diet. Group B aimed for substantial weight loss (SWL 10-15% body weight) using a modified Very Low Energy Diet (VLED). Participants were observed for 12-months to determine if pregnancy occurred. Time to conception is calculated as the time from the end of the 12-week weight loss intervention to a derived date based on menstrual period and/or ultrasound dates.
Results: Of the 164 women enrolled in the study, n= 124 (76%) completed the weight loss phase of the study and were considered in the current analysis. Mean weight loss achieved was 3.1+/-3.9kg (3.1%) and 12.9+/-5.1kg (12.0%) in Groups A and B respectively. Of completers, n=71 achieved pregnancy (Group A n=30; Group B n=41); the observation period is ongoing in n=38 completers. Time to conception was 136.3 (+/- 94.7) days in Group A and 80.0 (+/-83.37) days in Group B (p=0.043). Miscarriage rate was n=7 (23%) and n=9 (21%) in Groups A and B respectively.
Conclusion: Substantial weight loss prior to conception decreases the time to conception in women with obesity when compared with modest weight loss.
Trial Registration: ANZCTR 12614001160628.