Weight management to optimise fertility
In males and females, fertility is impaired if body mass index (BMI) is too low or too high. Consider underlying causes of abnormal weight, including eating disorders, before starting fertility treatments. For those who are overweight or obese, see General principles of managing excess body weight. Before considering pharmacotherapy to induce ovulation, consider the need for weight loss. A 5% reduction in body weight in overweight or obese anovulatory females may improve response to ovulation induction and reduce the risk of gestational diabetes.
Rapid weight loss is not desirable because it may have effects on the fetus; females should wait at least 1 year after bariatric surgery before trying to conceive. The safety of weight loss medications (such as phentermine or liraglutide) in pregnancy is unknown; their use is not recommended in females planning pregnancy. The impact of bariatric surgery on male fertility is not clear; studies have conflicting results.
The BMI threshold for fertility treatment in females is controversial. Several authorities suggest BMI should be below 35 kg/m2 before treatment, including assisted reproductive technology; however, the female’s age and time remaining for fertility treatment should be considered.