The amount of physical activity that women undertake is not linked to their risk of early menopause, according to the largest study ever to investigate this question.

Until now, there have been conflicting findings about the relation between physical activity and menopause, with some studies suggesting that women who are very physically active may be at lower risk of a menopause before the age of 45, while others have found evidence of the opposite effect.

However, the study that is published in Human Reproduction [1], one of the world's leading reproductive medicine journals, has analysed data from 107,275 women, who were followed prospectively from the time they joined the Nurses' Health Study II in 1989 until 2011, and found no association between physical activity at any age and early natural menopause.

Dr Elizabeth Bertone-Johnson, Professor of Epidemiology at the University of Massachusetts, USA, who directed the research, said: "Our study provides considerable information in helping us understand the relationship between activity and timing of menopause; this is because of its size, its focus on early menopause specifically, and because of its prospective design, which limited the likelihood of bias and allowed us to look at physical activity at different time periods.

"Several previous well-designed studies have found suggestions that more physical activity is associated with older age at menopause, but even in those studies the size of the effect was very small. Our results, in conjunction with other studies, provides substantial evidence that physical activity is not importantly associated with early menopause."

Female US registered nurses aged 25-42 were enrolled in the Nurses' Health Study II in 1989 and they completed questionnaires about lifestyles and medical conditions every two years thereafter. They were asked about the time they spent in recreational physical activities such as walking, running, cycling, racquet sports, swimming laps, aerobic activities, yoga, weight training and high intensity activities such as lawn mowing. The researchers also collected information on factors such as race, ethnicity, age, education, height, the age when the women had their first periods, whether or not they had been pregnant and how often, use of oral contraceptives and hormone therapy, whether or not they smoked, weight and body mass index (BMI), diet and use of dietary supplements.

In order to assess the frequency, duration and intensity of the activities, the researchers multiplied the hours per week of each activity by its metabolic equivalent (MET) score to create total MET hours per week. One MET equals one kilogram calorie per kilogram per hour (kcal/kg/h), which is the amount of energy expended by sitting quietly for an hour.

During the 20 years of follow-up, 2786 women experienced natural menopause before the age of 45. The researchers found no significant difference in the risk of early menopause between, for instance, women reporting less than three MET hours a week of physical activity and women reporting 42 or more hours a week (the equivalent to four or more hours of running or eight or more hours of brisk walking per week). The amount of physical activity that the women reported in their teenage years was also unrelated to the risk of early menopause.

A study suggests chemotherapy may cause acute amenorrhea leading to early menopause in women with lung cancer. The study is the first to comment on amenorrhea rates in women younger than 50, concluding that women with lung cancer who desire future fertility should be educated about risks and options before starting treatment. 

According to the Mayo Clinic, although the rate of lung cancer diagnoses in men has decreased by 32% since 1975, it has risen 94% percent in women and now has surpassed breast cancer as the leading cause of cancer death in US women. Although lung cancer is more common in older adults, women are diagnosed at a younger age compared with men, and approximately 5,000 premenopausal US women are diagnosed with lung cancer annually. Extensive research of women receiving treatment for breast cancer has found that between 40% and 80% have premature menopause. However, early menopause rates after lung cancer treatments are understudied.

Unique to the premenopausal survivor population is the concern that systemic chemotherapy may cause acute amenorrhea and menopause, leading not only to hot flashes, vaginal dryness, and bone loss but also the possibility of loss of fertility. Premenopausal women with lung cancer may want children and should consult their healthcare providers about options for embryo and oocyte cryopreservation, the gold standard for fertility preservation.

The study included 182 premenopausal women (average age at diagnosis, 43 years). The Mayo Clinic Epidemiology and Genetics of Lung Cancer Research Program surveyed women between 1999 and 2016 at diagnosis and annually thereafter about their menstrual status. Types of lung cancer treatments were recorded, and frequencies of self-reported menopause at each survey were calculated.

The results of the study appear in the article "Amenorrhea after lung cancer treatment." Although the study is small, for the 85 women who received chemotherapy, 64% self-reported that they were menopausal within a year of diagnosis. Only 15% of the 94 patients who did not receive systemic therapy within a year of diagnosis experienced self-reported menopause. Three patients received targeted therapy alone, two of whom remained premenopausal at the final survey completed a median of 3 years after diagnosis. The results suggest that chemotherapy for patients with lung cancer increases the risk of the early loss of menses in survivors.

"Although more definitive research is needed, premenopausal women who need chemotherapy for lung cancer appear to have a similar risk of amenorrhea, early menopause, and loss of fertility as premenopausal women receiving chemotherapy for breast cancer and lymphoma," according to Dr. JoAnn Pinkerton, executive director of NAMS. "I agree that premenopausal patients with lung cancer need to be educated about the risk for chemotherapy-related amenorrhea, menopause issues (hot flashes, vaginal dryness, and bone loss), and the potential loss of fertility before chemotherapy is initiated."