Research

Hormonal

Female overweight (BMI 25-29), obesity (BMI 30-34), and very obesity (BMI >=35) are associated with significantly reduced fecundability (longer time-to-pregnancy) compared to normal weight women, with the association strengthening when central adiposity (waist circumference) is controlled for.

If you are trying to conceive and have a BMI in the overweight or obese range, your time-to-pregnancy may be significantly longer than if you were normal weight. This effect is even stronger if you carry excess weight around your waist. While weight loss is not a guaranteed fix, maintaining a healthy weight may improve your chances of conceiving naturally within a typical timeframe.

GoodSupportsHIGH confidence
We found longer TTPs for overweight (FR = 0.83, 95% CI = 0.70 –1.00), obese (FR = 0.75, 95% CI = 0.58– 0.97), and very obese (FR = 0.61, 95% CI = 0.42– 0.88) women, compared with normal weight women. After further control for waist circumference, FRs for overweight, obese, and very obese women were 0.72 (95% CI = 0.58 –0.90), 0.60 (95% CI = 0.42 –0.85) and 0.48 (95% CI = 0.31– 0.74), respectively.
Lauren A. Wise et al. · Human Reproduction · 2009

Why this rating

Prospective cohort study with large sample size (n=1651) and rigorous statistical controls, though self-reported anthropometric data introduces minor measurement error.

Source

An internet-based prospective study of body size and time-to-pregnancy

Lauren A. Wise et al. · Human Reproduction · 2009

DOI 10.1093/humrep/dep360

cohort · n=1651Cited 265×
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DOI resolved against Crossref · corpus check 2026-06-10

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