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BJOG press release: Obesity and smoking during pregnancy associated with higher risk of PCOS in daughters

News 13 June 2018

Women who smoke and are obese during pregnancy are more likely to have daughters who develop polycystic ovary syndrome (PCOS) later in life, according to a large study published online in BJOG: An International Journal of Obstetrics and Gynaecology.

Daughters born to obese women – defined as having a body mass index (BMI) of 30 or over – had double the relative risk of developing PCOS compared to those born to normal weight mothers. The absolute figures showed that 5 in 1000 girls will develop PCOS. This increased to 7 in 1000 girls if the mother was obese during pregnancy and 8 in 1000 if the mother was overweight (a BMI of 25-30).

The absolute risk increased to 8 in 1000 girls if the mother was a heavy smoker – defined as smoking 10 cigarettes or more per day – compared with a non-smoker.

Researchers analysed more than 680,000 girls who were born in Sweden between 1982 and 1995 to examine the associations between prenatal exposures and the associated risk of developing PCOS. By 2010, 3,738 (0.54%) of girls had been diagnosed with the condition.

PCOS is a common condition that influences how a woman’s ovaries work and can cause irregular periods and an excess of androgen ‘male’ hormones which can lead to excess facial or body hair. Symptoms can also include fertility problems, weight gain, hair loss and oily skin, and the condition can have a significant impact on quality of life.

While the exact cause of PCOS is unknown, it tends to run in families and is associated with high levels of insulin which worsens symptoms. Many women with PCOS are resistant to insulin and produce higher levels of the hormone to overcome this. Being overweight or obese also increases the amount of insulin produced. Higher levels of insulin increase the production of other hormones, such as testosterone. 

Lead author of the study, Dr Heiddis Valgeirsdottir, a Consultant Obstetrician and Gynaecologist at the Department of Women’s and Children’s Health, Uppsala University in Sweden, said:

“The results of this study add to existing evidence that being overweight or obese during pregnancy is a risk factor for development of PCOS in daughters in later life, yet so much about the cause of this condition remains unknown. The results also show an association between smoking in pregnancy and PCOS development in daughters.  While our study shows only an association, and therefore no definitive conclusions can be made about cause and effect, we would advise women to stop smoking and ensure a healthy weight in order to reduce the associated risk.”

Dr Melanie Davies, Consultant Obstetrician and Gynaecologist, and Spokesperson for the Royal College of Obstetricians and Gynaecologists (RCOG), said:

“This large scale study highlights the importance of women stopping smoking and maintaining a healthy weight, by ensuring a well-balanced diet and taking part in regular exercise before and during pregnancy to give their child their very best start in life. The same applies to women who develop PCOS. There is no cure for PCOS, but stopping smoking, ensuring healthy eating and being active can improve or prevent many symptoms associated with PCOS by helping to balance the level of hormones.”

Dr John Thorp, Deputy Editor of BJOG, said:

“The results of this study emphasise the need to raise awareness of the adverse effects of smoking and obesity in pregnancy. Women tend to be more receptive to making healthy changes before conception and during pregnancy, and healthcare professionals have an unparalleled opportunity to support women in making such adjustments in order to ensure the best possible outcomes for themselves and their babies.”


Note to editors

For media enquiries please contact the RCOG press office on +44 (0)20 7045 6773 or email

Public link to paper when published:

Please cite this paper as: Valgeirsdottir H, Vanky E, Sundstr€om-Poromaa I, Roos N, Løvvik TS, Stephansson O, Wikstr€om A-K. Prenatal exposures and birth indices, and subsequent risk of polycystic ovary syndrome: a national registry-based cohort study. BJOG 2018


RCOG information about PCOS:

About BJOG
BJOG: An International Journal of Obstetrics and Gynaecology is owned by the Royal College of Obstetricians and Gynaecologists (RCOG) but is editorially independent and published monthly by Wiley. The journal features original, peer-reviewed, high-quality medical research in all areas of obstetrics and gynaecology worldwide. Please quote ‘BJOG’ or ‘BJOG: An International Journal of Obstetrics and Gynaecology’ when referring to the journal. To keep up to date with our latest papers, follow @BJOGTweets.

About the RCOG
The Royal College of Obstetricians and Gynaecologists is a medical charity that champions the provision of high quality women’s healthcare in the UK and beyond. It is dedicated to encouraging the study and advancing the science and practice of obstetrics and gynaecology. It does this through postgraduate medical education and training and the publication of clinical guidelines and reports on aspects of the specialty and service provision.