Early birth control pill use a red flag for endometriosis

Young women who start taking hormonal contraceptives early in life may be at increased risk of endometriosis, as suggested in a study.

Researchers used data from Swedish national registers and looked at 720,805 women aged 12–27 years (mean age 17.5 years) during 2005–2017. Endometriosis was diagnosed in 3,268 (0.45 percent) women at a mean age of 21.2 years, with an incidence rate of 4.95 per 10,000 person-years.

Women with vs without endometriosis were more likely to have completed a higher level of education, to have children and be married, and to have used hormonal contraceptives at some point before receiving the diagnosis.

Notably, among women who used hormonal contraceptives, those who had endometriosis were almost three times more likely as those without the diagnosis to have begun using hormonal contraceptives before the age of 15 years (9.1 percent vs 3.8 percent) and to have tested a greater number of different types of pills.

Multivariable Cox regression analysis showed that the risk of receiving a diagnosis of endometriosis was more than twofold higher among women who started using hormone contraceptives at ages 12–14 years than among those who began at 17 years or older (adjusted hazard ratio [aHR], 2.53, 95 percent confidence interval [CI], 2.21–2.90). Having tried more types of hormonal contraceptives was associated with a twofold increased risk of endometriosis (more than three types: aHR, 2.31, 95 percent CI 1.71–3.12).

Conversely, use of hormonal contraceptives for more than 1 year was negatively associated with the risk of endometriosis (>1 year: aHR, 0.53, 95 percent CI, 0.48–0.59).

Dysmenorrhea, depression, and infertility were common among women with endometriosis.