Women in a Chinese study who sat for more than six hours each day faced substantially higher odds of developing uterine fibroids before menopause, a new study has found.

Overall, more sedentary women had double the risk of developing the often painful and harmful uterine growths prior to menopause, say a team led by Dr. Qiong Meng , of Kunming Medical University in Kunming, China.

Why the link? Obesity linked to a ‘couch potato’ lifestyle could be one factor, since “studies have shown that obesity is a risk factor for uterine fibroids,” Meng’s group noted.

Sedentary lifestyles and obesity are also tied to rising levels of circulating estrogen, as well as other hormones known to contribute to fibroids, the team added. Finally, being sedentary can also help lead to deficiencies in vitamin D — yet another risk factor for these growths.

The findings were published Nov. 29 in the journal BMJ Open.

According to the study team, uterine fibroids are benign tumors that are exceedingly common among women. They sometimes cause no symptoms, but in many cases can trigger “abnormal bleeding, pain in the pelvic and abdominal organs, adverse reproductive outcomes of infertility,” the researchers noted. Sometimes fibroids become so severe that a hysterectomy is advised.

In the new study, Meng’s team analyzed data on over 6,600 women from across China who were between the ages of 30 and 55. None had yet gone through menopause. Eighty-four percent of the women had had more than two children.

Sedentary behavior included sitting or lying down and activities such as watching screens, knitting, reading or playing board games.

In total, 8.5% of the women in the study developed fibroids, which became more common as the women got older.

Among other factors, weight and having two or more kids were tied to a rise in the risk for fibroids.

So was being sedentary: According to a journal news release, “the risk was five times higher among those who clocked up six or more sedentary leisure hours a day than it was in those who clocked up fewer than two hours.”

This effect was seen only among overweight or obese women, however.

The research was observational, so it couldn’t prove a cause-and-effect link, the researchers stressed. However, the study “suggests that in overweight or obese individuals, other factors may influence the development of uterine fibroids,” Meng’s team concluded.

More information

Find out more about uterine fibroids at the Mayo Clinic.

SOURCE: BMJ Open, study and news release, Nov. 29, 2023

What This Means for You:

Premenopausal women may want to limit their hours spent sitting, with sedentary lifestyles now tied to a higher risk for uterine fibroids.