For a study, researchers sought to see if obesity was linked to a longer time of pregnancy in a group of women who were trying to get pregnant after ceasing their contraception. The FACT (Fertility After Contraceptive Termination) research was subjected to secondary analysis. The prospective study included 432 women between the ages of 18 and 35 who had stopped using contraception to become pregnant, were sexually active with a male partner and supplied pregnancy status data within the first 12 months. The primary outcome, time to pregnancy, was calculated from the moment contraception was stopped to the projected due date. While adjusting for potential confounding variables, they used Cox proportional hazard models to investigate correlations between normal (< 25.0), overweight (25.0–29.9), and obese (30 or >) body mass index (BMI) with time to pregnancy. 

After controlling for covariates, participants with a BMI of 30 or higher were shown to have a longer time to pregnancy than those with a BMI of 25 or less (aHR 0.62; 95% CI 0.44–0.89). Participants with normal BMIs had a median time to pregnancy of 5.3 months (95% CI 3.8–6.4), compared to 8.2 months (95% CI 6.8–10.8) for those with obesity. Participants with BMIs less than 25, 25–29.9, and 30 or more had pregnancy rates of 76.4% (95% CI 69.7–82.6%), 69.5% (95% CI 60.5–78.1%), and 59.1% (95% CI 51.0–67.4%) at one year, respectively. Menstrual irregularity was similarly linked to lower fertility (aHR 0.67; 95% CI 0.46–0.97).

Participants with obesity who stopped contraception with the purpose of becoming pregnant had a longer time to pregnancy than those with normal BMIs. Understanding the causes of this link will help patients and clinicians make better decisions.