A new study has identified risk factors associated with the development of premature ovarian failure (POF) and early menopause. Researchers from centers in Chungju, Seoul and Ilsan, in the Republic of Korea, set out to identify premenopausal risk factors associated with idiopathic POF and early menopause in Korean women, and to find out if the risk factors for POF are distinct from those for early menopause.For the study, menopause was defined as a period of amenorrhea of more than 12 consecutive months. POF was defined as the cessation of menstruation before the age of 40 years, and early menopause was defined as the occurrence of menopause at age 40-44 years. The study population, recruited from local districts as part of a larger study investigating cancer, consisted of 84 women with idiopathic POF, 261 women with idiopathic EM (women with surgical or medical menopause were excluded) and a control group of 1,318 women with ‘normal’ menopause, at age 45-60. The women provided information on their premenopausal lifestyle and reproductive factors.
The main findings of the study, reported in a new paper in the journal Maturitas, include:
Cigarette smoking was significantly associated with idiopathic POF, but not early menopause: the odds ratio of developing idiopathic POF was 1.82 for women who had ever smoked, compared with those who had never smoked. Environmental smoking (defined as a woman living in the same house for at least 1 year prior to menopause with a family member who smoked at least 20 packs of cigarettes in a lifetime) was also significantly associated with idiopathic POF, but not early menopause.
Being 13 years-old or younger at menarche significantly increased the risk of idiopathic POF and idiopathic early menopause.
Having a regular menstruation cycle (defined as occurring every 21-35 days) significantly reduced the risk of idiopathic POF and idiopathic early menopause (odds ratio 0.55, 95 percent confidence interval 0.32-0.95).
Using oral contraceptives significantly reduced the risk of idiopathic early menopause, but not idiopathic POF.
Among parous women, breast-feeding for 24 months or more significantly reduced the risk of idiopathic POF, but not early menopause.
Other environmental, physical and reproductive factors investigated – including alcohol consumption, physical activity per week, sedentary time per day, exposure to agricultural chemicals, parity, and spontaneous abortion in the first pregnancy – did not show any significant relationship with idiopathic POF or early menopause.
The researchers discuss their findings in detail, including the biological mechanisms likely to account for some of the associations such as with cigarette smoking. They conclude that they were able to identify some risk factors that were specific to either POF or early menopause, but that many of the risk factors related to ovulation, such as later menarche, irregular menstruation, and longer duration of breast feeding, were common to both POF and early menopause.