Obesity and infertility – the impact of body weight on fertility in women and men

Obesity can adversely affect health and can cause problems with blood circulation, heart function, hypertension and the skeletal system. However, these are not the only areas where we can experience problems resulting from excessive weight.

According to researches carried out over many years and, as confirmed cases show, high BMI can cause fertility problems, both in women and men, causing, among others, ovulation disorders and deterioration of semen parameters in men by a negative impact on the work of hormones. How can overweight and obesity affect fertility in both men and women, and what complications can they cause if they become pregnant?

Fertility disorders in women and men caused by overweight and obesity

Having a high BMI can result in various changes in the body, affecting, among others the disruption of normal hormonal balance and it can elevate inflammatory conditions that impede fertilisation and impair fertility both in women and men. Notwithstanding, each case needs to be looked at individually, because although there is a large group of possible complications and fertility disorders resulting from being overweight, not all of them may occur in every patient and it is not excluded that new problems may appear, that previously have not been related to obesity.

In women, possible obesity-related fertility disorders include insulin resistance, ovulation problems and excessively high levels of androgens, the hormones responsible for the development of certain sexual characteristics in the foetus. Ovulation disorders may prolong the time to get pregnant due to the difficulty of hitting the exact day of ovulation or egg fertilising due to the occurrence of non-ovulatory cycles.

Further, a more excessive body weight leads more often to endometriosis and polycystic ovarian syndrome (PCOS), both of which have a direct impact on conceiving problems. Importantly, obesity and overweight-related disorders in women can lead not only to problems with conception but also with maintaining a pregnancy and cause a number of complications when it comes to carrying a pregnancy to term.

In men, excessive body fat causes excessive estrogen production and testosterone deficiency, which significantly reduces sperm characteristics and can make conception difficult. Obesity also reduces the secretion of growth hormone which in men has impact on sperm production.

Can being obese cause complications during pregnancy?

The first problem for a woman who become pregnant will be a significantly higher risk of spontaneous miscarriage if she is overweight – excess body fat adversely affects the hormonal balance, causing, among other things, a reduction in the secretion of FSH, LH, oestradiol, AMH and progesterone necessary to maintain the pregnancy and its normal development. Obesity is also associated with increased risk of insulin resistance, hyperinsulinemia, diabetes and hypertension, which require constant monitoring and may pose additional risks to pregnant women.

Excessive body weight has a negative impact on pregnancy and foetal development because it does increase the risk of complications and birth defects and making prenatal diagnosis, including even a basic ultrasound examination, more difficult. Overweight women may experience problems during pregnancy with fluctuations in blood pressure, respiratory problems, cholecystitis, thrombotic complications, gestational diabetes, as well as exposing the baby to increased weight at birth. Among the more serious complications associated with maternal overweight are foetal abnormalities, the risk of spina bifida, a higher risk of haemorrhage during childbirth and also perinatal infections.

Does obesity cause permanent fertility problems?

The consolation for obese people planning to get pregnant and have a baby in the future is that in many cases, fertility problems, that are related to obesity, are not permanent, and even a small loss of weight can increase the likelihood of pregnancy. Therefore, unless many years of overweight or obesity led to disorders that are difficult to treat and require constant monitoring, such as diabetes or insulin resistance, the chances of getting pregnant and hence the fertility in both women and men should increase as the BMI returns to a lower, normal level. It is worth trying to lose weight in advance, so that the woman’s body in particular can prepare for the foetus and the child’s proper development up to birth.