Weight Loss and Fecundity Among Women with Overweight or Obesity: A Real-World Data Cohort Study

Background: Women living with overweight or obesity face more difficulties conceiving and are at higher risk of pregnancy complications than women with normal weight. This study examined the association between weight loss and fecundity among women with overweight or obesity. Methods: Between 2000 and 2020, 246,713 women aged 18-40 years with BMI≥25 kg/m2 were followed using UK health records for a median (IQR) of 185 days (67, 912). Cox regression was used to compare time to pregnancy between women who lost 10%25% of their weight during a 2-year baseline period and women who maintained their weight (±3%). Follow-up started after the baseline period and was truncated at 3 years, at prescription of contraceptives or at the start of fertility treatment. Adjustments were made for smoking status, parity, baseline health status including polycystic ovary syndrome, socioeconomic status, age, ethnicity, and baseline BMI. Risk of pregnancy complications (gestational diabetes and pregnancy-induced hypertension) was estimated using logistic regression adjusted for the same covariates. Results: 195,666 women maintained, and 51,004 lost 10%-25% of their weight (median weight loss 14%). Baseline BMI was slightly higher, and follow-up time was shorter in the weight loss group (BMI 29.4 vs BMI 28.4, and 166 days vs 191 days, respectively). Women in the weight loss group had a 5.8% (HR 1.06; 95% Cl: 1.02,1.10) higher rate of conception, 42% (OR 0.58; 0.49, 0.69) lower odds of gestational diabetes, and 20% (OR 0.80; 0.62, 1.04) lower odds of pregnancy-induced hypertension, compared to women who maintained their weight, accounting for measured confounders. Conclusions: In a real-world population of women living with overweight or obesity, a median weight loss of 14% is associated with improved rates of conception and reduced occurrence of pregnancy related complications. Our findings provide further evidence of the benefits of weight loss on fecundity among women living with overweight or obesity.