Obesity could increase risk of female reproductive disorders

A study by University of Oxford researchers suggests an etiological link between obesity and a range of female reproductive conditions, but the extent of this link differs among conditions. Although reproductive disorders are common conditions affecting the health and well-being of many, the role of obesity in the development of female reproductive conditions is under-studied. The paper, 'Obesity and risk of female reproductive conditions: A Mendelian randomisation study', published in PLoS Medicine.

Obesity is associated with risk of female reproductive conditions. Our work shows that the estimated genetic and observational effects of obesity on various reproductive conditions are heterogeneous and partly mediated by hormones. We further see that reproductive disorders cluster by the shared genetic effect of obesity. Credit: Samvida S. Venkatesh, CC BY 4.0 (creativecommons.org/licenses/by/4.0/)

To investigate the causal associations between obesity, metabolic hormones, and female reproductive disorders, researchers conducted a Mendelian randomisation study of 257,193 women of European ancestry aged 40-69. They accessed records from UK Biobank, a large-scale biomedical database containing the medical, environmental, and genetic information of participants.

The researchers then created a statistical model to estimate the association of body mass index and waist-to-hip ratio with risk of numerous female reproductive conditions including endometriosis, heavy menstrual bleeding, pre-eclampsia, and infertility.

The researchers found observational associations between obesity and a range of female reproductive disorders, including uterine fibroids, polycystic ovary syndrome, heavy menstrual bleeding, and pre-eclampsia. They also found that some inherited genetic variation associated with obesity is also associated with female reproductive disorders, but the strength of those associations differed by type of obesity and reproductive condition.

The study had several limitations, such as the low prevalence of female reproductive disorders among participants, and a lack of body mass index and waist-hip-ratio data prior to disease onset.

"We provide genetic evidence that both generalised and central obesity play an aetiological role in a broad range of female reproductive conditions, but the extent of this link differs substantially between conditions,” the authors wrote. “Our results suggest a need to explore the mechanisms mediating the causal associations of overweight and obesity on gynaecological health to identify targets for disease prevention and treatment.”

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