top of page

Obesity and Reproductive health

M, 30, had been married for the past 3 years and had not been able to conceive. She had her first menstruation at the age of 12. Her menstruation had been irregular, occurring once every month to one and half months. Her periods usually lasted 5 days. Since she got married, the cycle had changed to once in 2 to 3 months lasting between 3 to 12 days. The amount varied from scanty to heavy flow with clots. There were no abdominal cramps or discomfort during menses.

She was obese with a BMI of 32. Clinical examination of her reproductive organs was normal. Pelvic ultrasound examination revealed enlarged ovaries with multiple small cysts. Blood hormonal tests confirmed that she had polycystic ovarian syndrome (PCOS).

Her spouse, aged 34, was also obese with a BMI of 34. Semen analysis revealed suboptimal numbers of sperm with reduced motility.

Prevalence of Obesity

Obesity, defined as an excessive accumulation of body fat, is a global health issue. In Singapore, one in 10 adults is considered obese according to the most recent surveys by the Ministry of Health. Besides health risks such as cardiovascular diseases and diabetes, an important but often overlooked consequence of obesity is its impact on fertility.


Impact of Obesity on female reproductive health

Obesity affects female reproduction by the following mechanisms:

  • Excess body fat produces abnormally high levels of female hormone, oestrogen. This results in disruption of hormonal balance and leads to irregular menstrual cycles due to absent or infrequent ovulation.

  • Obesity is closely linked to polycystic ovary syndrome (PCOS).  The increased levels of male hormones and insulin resistance in PCOS make it more difficult for conception to occur.

  • Fat tissues also produce leptin, the hormone that regulates energy balance. High levels of leptin in obesity can cause inhibition of ovulation, resulting in infertility.

Moreover, obesity increases the risk of pregnancy complications such as gestational diabetes, preeclampsia, and miscarriage. These complications not only threaten the health of the mother but also reduce the likelihood of a successful pregnancy. The reduced efficacy of in vitro fertilization (IVF) in obese women further underscores the adverse impact of obesity on female reproductive health.


Impact of Obesity on Male Fertility

Obesity can affect male fertility in the following ways:

  • Excess body fat can lead to the increased conversion of male hormone, testosterone, to estrogen in the fat tissue, resulting in lower levels of circulating testosterone. This hormonal imbalance can impair the production of sperm and reduce libido.

  • Obesity is associated with erectile dysfunction (ED), which impairs the ability to engage in sexual intercourse and thus decreases the chances of conception. The increased prevalence of diabetes and cardiovascular disease among obese men further contributes to ED.

  • Obesity is also linked to poor semen quality, including reduced sperm concentration, motility, and morphology.

  • The oxidative stress and inflammation associated with obesity can damage sperm DNA, further compromising male fertility.  

M and her spouse understood the negative impact of obesity on fertility and general health. They were motivated and expressed the wish to support each other on weight management. Lifestyle changes, including eating a balanced diet and regular exercises, are the mainstay in reducing weight. A reduction of 5-10 % of weight is found to improve both egg and sperm health. M was also given medications to correct her hormonal imbalance and her spouse was prescribed micronutrients to help improve sperm quality. They are progressing well albeit slowly on their long journey to achieve pregnancy.


bottom of page