• Dr Peter Chew

Obesity and infertility

Updated: Nov 12, 2018

Q. I am 30 years old and have been married for 3 years. Recently, I am trying to conceive. My menses are rather irregular occurring once every 6 weeks to 2 months.  My gynecologist thinks my menstrual irregularity is due to my being overweight as my BMI is 27. He advises me to lose weight if I want to become pregnant. How does obesity affect fertility? I have difficulty losing weight. I have tried taking appetite suppressant drugs. I lose weight temporarily but I become fat again as soon as I stop taking medicine. I am rather depressed. Can you help? Will surgery to reduce stomach help?


A. Normal menstruation essentially depends on the balance of two hormones (estrogen and progesterone) produced by the ovary. These hormones, in turn are influenced by pituitary gland (a small gland at the base of the brain) as well as other centers in the brain. There are two sources of estrogen in the body. The main source is the ovary while an indirect and small source is from the adrenal gland (a small gland on top of kidney). The ovary produces estrogen directly and cyclically while the adrenal gland produces estrogen indirectly through the fat cells. In obese patient, the erratic inflow of estrogen from the fat cells interferes with the cyclical estrogen production of the ovary. This ultimately results in disturbance in ovulation and infertility.

Another reason for obese patients to be infertile is its association with a disorder called PCOS (polycystic ovarian syndrome) where there is excess of male hormone (testosterone) and a diabetic-like state in the body. This deranged biochemistry makes the ovary unlikely to ovulate or produces poor quality eggs.


There is no easy and quick-fix way to weight loss. An approach involving lifestyle changes through proper diet, exercise, behavior modification, stress reduction together with medications is found to be most effective. The key to successful weight loss lies in your brains, not in your stomach.


You may consider the following:

• Joining a slimming group. Group work, with regular weigh-ins and sharing of experiences, can help motivation.

• Learn your own weaknesses and food triggers: look for ways to beat them

• Tell people you are dieting - you might bore them, but it helps you to commit to the idea

• Do not be overambitious - a gradual loss of 1kg max a week is the most you should expect.


Medical research has shown that a reduction of 10% of body weight in obese patients may correct the hormone and metabolic derangements. This will increase the chances of conception. Stomach stapling is not advisable in your case as you are not extremely obese. It is an invasive procedure and carries surgical risks. It should be used as a last resort.

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