Association between PCOS, BMI and pregnancy

Author: Dr Durga G Rao, Co-Founder & Medical Director, Oasis Fertility

PCOS (Polycystic Ovary Syndrome) has become very common these days with 1 in 5 women living with it. It is the most prevalent endocrine disorder that affects 8-13% of premenopausal women. The major reproductive features of PCOS are increased androgen production, and disordered gonadotropin secretion that results in menstrual irregularity, excess body hair, acne, and infertility.

In most cases, women with PCOS are obese and it’s a vicious circle. 38% – 88% of women with PCOS have overweight / obesity and the most important thing is obesity lowers the chance of pregnancy and increases the risk of miscarriage. Research also suggests that there is a remarkable improvement in the success rate of pregnancy in the case of women who try to lose weight.

Let us gear up to know how one’s BMI (Body Mass Index) is directly related to the chance of conception and also how weight loss can improve the chances of pregnancy.

What is BMI:

BMI helps to know if one has a healthy weight using his or her’s height-to-weight ratio.

BMI chart:

BMI less than 18.5 – underweight

BMI ranging from 18.5 < 25 – healthy weight

BMI ranging from 25 < 30 – overweight

BMI is 30 or higher – obesity

Obesity is further divided into:

Class 1: BMI 30 < 35

Class 2: BMI 35 <40

Class 3: BMI of 40 and higher than 40

In women with PCOS, a higher baseline BMI is associated with a lower chance of pregnancy. The chance of pregnancy was studied across the range of ages at PCOS diagnosis (18–45 years) for the five BMI categories using a woman with normal weight aged 27 years at PCOS diagnosis as the reference.

For a woman with obesity class II (BMI 35–39.9) aged 31 years at PCOS diagnosis, the chance of pregnancy was half that of a woman with normal weight aged 27 years. Also, her chance of conception was similar to that of a woman with normal weight aged 35 years at diagnosis.

Chance of pregnancy based on age at PCOS diagnosis by BMI category

 

Source: Association between body mass index, weight loss and the chance of pregnancy in women with polycystic ovary syndrome and overweight or obesity: a retrospective cohort study in the UK  Human Reproduction, Vol.38, No.3, pp. 471–481, 2023

Association between weight loss and pregnancy: 

International guidelines recommend lifestyle modification including weight management as the first line of treatment for most women with PCOS and overweight/obesity. Weight loss is associated with an increased chance of pregnancy versus maintaining a stable weight or gaining weight. Losing weight may improve fertility outcomes by mediating improvements in hormone profiles, ovulation rates, oocyte health, endometrial receptivity, insulin resistance and other metabolic parameters.  

Key Takeaways:  

                1. A higher BMI lowers the chance of pregnancy in the case of women with PCOS.

                2. Weight loss following PCOS diagnosis is associated with an increased chance of pregnancy compared with maintaining a stable weight or weight gain. 

                3. 5-15% weight loss after PCOS diagnosis can increase the chance of pregnancy. 

                4. Less than 10% of women can conceive whose BMI is more than 45. 

                5. For a woman aged 31 (at PCOS diagnosis) with a BMI more than 35, the chance of conception is half that of a woman aged 27 with normal weight. 

                6. The chance of conception of a woman aged 31 with a BMI more than 35 is similar to that of a woman with normal weight and aged 35 at PCOS diagnosis. 

                7. The chance of pregnancy for a woman with a BMI equal to or greater than 40 was expected to be 63% lower when compared to a woman with normal weight.

                8. Gaining 5% weight after PCOS diagnosis slightly reduces the chance of pregnancy. 

Key Indicators	Chance of Pregnancy
PCOS+ Weight Gain	Low
PCOS + Weight Loss	High
PCOS + Stable Weight	Low

 

Health Goals for women with PCOS and overweight: 

PCOS cannot be cured; Don’t lose hope. Lifestyle modifications can help you stay healthy and also help in conception. Several pregnancy-related complications also can be avoided by having a balanced diet, weight loss, and exercising regularly. Stay motivated and follow a strict regimen that can make you happy and healthy.  

If you are planning to conceive, try to have a healthy weight. Weight loss can help in the regularization of the menstrual cycle and enable you to get pregnant. 

Insulin resistance is one major issue in women with PCOS. Try to avoid processed foods and reduce the intake of sugars; Include plenty of fibre and healthy fats to reduce the risk of Diabetes and heart disease. 

Burn your calories; Make exercise part of your daily routine.  

Foods to be Avoided	Food to be Included
Saturated fats (Biscuits, cakes, Butter)	Beans, green leafy vegetables
Red Meat	Brown rice, barley
Fried foods	Spinach, cauliflower, tomato
Alcoholic beverages	Salmon and other omega-3 fatty acid rich fish
Soda	Whole fruits