Women of a healthy weight (BMI <30) tend to have better pregnancy outcomes both naturally and through fertility treatments
There has been a lot of controversy in the medical literature about the importance of being at normal weight to optimize the outcomes of fertility treatment, especially IVF. Various groups have found either reduced pregnancy/delivery rates, but others have found no effect in women who are over the usual weight guidelines. (Don’t know your BMI? Try BMI-Calculator.net. BMI is not a perfect reflection of body fat percentage, but it’s used for most medical studies since actual percent body fat is much more difficult to determine).
Some infertility problems are affected greatly by weight and/or extremes of exercise. Many extremely lean and/or active women (example: ballerinas, elite athletes) lose their periods, and their fertility. Women with a genetic tendency to ovarian issues can develop irregular cycles and reduced fertility if they are over the normal weight range.
This is often correctable with weight loss.
There is little question that being overweight influences pregnancy outcomes. Obese, and certainly morbidly obese, women are at higher risk of many pregnancy complications including preeclampsia (blood pressure elevations which may lead to early delivery), diabetes, cesarean section, even birth defects and complications in the newborn (For more information, visit Pregnancy-Info.net).
We would all like to be in an ideal weight range, but achieving this goal can be difficult. Most medical complications related to weight are improved by even a 10 percent weight loss, which is manageable for most women. The usual mantra of good food choices, portion control and exercise seems to be the best approach for most people. Only rarely would bariatric surgery be considered unless a woman had other serious health issues like high blood pressure and diabetes. Bariatric surgery seems to lead to increased fertility and lowers the risk of pregnancy complications into a normal range.