Fertility and being overweight
If you’re trying to get pregnant, or intend to start trying, know that being overweight – especially significantly so – can affect your chances of conceiving and having a healthy baby. If you are overweight and planning to get pregnant in the next year or few years, you might commit to a healthy eating and regular exercise plan. Losing even a few kilos can make a difference. The father’s weight can also affect your chances of getting pregnant.
How can I tell if I’m ‘overweight’ or ‘obese’?
One common measure of whether a person is ‘overweight’ or ‘obese’ is the body mass index or BMI. You calculate your BMI by dividing your weight in kilograms by the square of your height in metres. A healthy BMI is considered to be between 18.5 and 24.9. Having a BMI between 25 and 29.9 is considered ‘overweight’ and a BMI over 30 is considered ‘obese’.
The facts about women, weight and fertility
Obesity can affect fertility by causing hormonal imbalances and problems with ovulation, particularly for obese women having their first baby. Obesity is associated with poly-cystic ovary syndrome (PCOS), a common cause of infertility. PCOS is a common hormonal condition especially in infertile women, affecting up to one in five women of reproductive age. Early diagnosis, living a healthy lifestyle and treatment can help optimise fertility.
If a mother is obese, it increases the risk of pregnancy complications and health problems for the baby. Risks associated with obesity in pregnancy include miscarriage, hypertension, pre-eclampsia , gestational diabetes, infection, blood clotting, need for induction of labour, Caesarean birth and stillbirth.
Babies born to overweight or obese mothers are more likely than those born to healthy-weight mothers to become obese children and adults, and to have more health problems.
For women with diabetes, it is especially important to plan for pregnancy. If possible, it is recommended to review your diabetes and your general health with your doctor, at least three to six months before trying to conceive.
- Women who are overweight or obese have less chance of getting pregnant overall. They are also more likely than women of healthy weight to take more than a year to get pregnant.
- The risk of pre-eclampsia doubles in overweight women and triples in obese women. Overweight women have twice the risk of gestational (pregnancy-related) diabetes and obese women eight times the risk, compared with women of healthy weight.
- A woman who is obese is more than twice as likely to have a miscarriage as a woman of healthy weight. There is twice the risk that her baby will not survive.
- Infants born to obese women are more likely to be large for their age, need neonatal intensive care or have a congenital abnormality.
- High levels of leptin and low levels of adiponectin may also reduce rates of conception.
Obesity and Infertility Treatment
Even with our most advanced treatments such as in vitro fertilization (IVF), pregnancy rates are reduced in a person who is obese. Obesity makes the IVF procedures of egg retrieval and embryo transfer more difficult. Even when these procedures go well, there is increasing evidence of a lower IVF pregnancy rate in obese patients.
Obesity in Men
Overweight and obese men are more likely to have lower sperm counts with lower motility (normal sperm movement). Being overweight or obese can also cause hormonal changes that reduce fertility and make men less interested in sex. Men who are very overweight are also more likely to have problems getting an erection. Together, these factors reduce the chances of men who are overweight or obese the chance of getting their partner pregnant naturally or having a successful fertility treatment.