The menstrual cycle changes with age, but the menopause and the time leading up to it can particularly throw its patterns out of sync.
Feeling that previous studies on the menstrual cycle were small and lacked a diversity of ages, at the period tracker app Flo in London and his colleagues analysed data that was self-reported by 19 million app users, aged between 18 and 55, from 2022 to 2023.
Overall, the team found that cycles became shorter and more variable as the users aged. An exception was between the ages of 47 and 55, when the length increases sharply, with a corresponding increase in cycle variability.
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Irregular cycles – defined as having various points in the year where the shortest and longest cycles differed by more than a week – were highest among 51 to 55-year-olds, but least common in those aged 36 to 40, compared with the other age groups.
When it comes to symptoms that occur during a period, users of all ages commonly reported cramps, breast tenderness and fatigue, as well as bloating and mood changes. Headaches were common among those aged 46 to 55.
In the and the , the average age when the menopause starts is 51, but perimenopause – the transition to menopause when oestrogen levels start to fluctuate – and can be accompanied by changes to the menstrual cycle and its effects.
This is important to study because knowledge of the menstrual cycle during the perimenopause and menopause is “really at a minimal level”, says at healthcare provider Northwell Health in New York, who wasn’t involved in the research. “People don’t know what to expect in menopause, so I think this could relieve some of their concerns.”
A 2022 by the UK’s Department of Health and Social Care reported that fewer than 10 per cent of women said they had received enough information on the menopause, with “menstrual health” being a key concern.
“Understanding these age-related differences in cycle characteristics and symptoms is important in understanding how best to care for and improve daily experience for menstruators across the reproductive lifespan,” according to the researchers.
Society views ageing as a medical condition, but this data shows the “physiology” of how menstrual cycles specifically change with age, says team member at Yale School of Medicine.
When interpreting the results, Metz says it is important to note that nearly half of the respondents fell into the 18-to-25 age category, with the number of app users declining in older age groups.
Using self-reported data also runs the risk that users forgot to input information or recorded it inaccurately. When they forgot to record their last bleeding day, the researchers automatically assigned a bleeding length of five days for that period.
Metz also points out that while the results are based on a large sample size, the data wasn’t broken down according to the participants’ or whether they had common conditions such as endometriosis or polycystic ovary syndrome, which can cause painful or irregular periods.
medRxiv
