This is mainly from The Centre for Menstrual Cycle and Ovulation Research at the University of British Columbia. It’s an incredible resource by the way— the most useful I’ve found so far.
Perimenopause is the period of time before and for a year after the last menstrual period during which ovarian hormonal patterns, experiences and sociocultural roles change. The average age at which irregular cycles develop is about age 47.
In CIS women with regular cycles perimenopause probably begins several years before that. It’s when the ovaries start are making fluctuating amounts of estrogen (often higher than before perimenopause) and lower amounts of progesterone.
Like menopause, perimenopause is a normal part of a CIS woman’s life cycle. However, everything about perimenopause is variable. It’s variable within oneself. It’s even more variable between individuals— even if those who are siblings or relatives.
By the way, I’m using the word CIS woman, but this information can also apply to nonbinary and transgender folks with estrogen-based reproductive systems who haven’t taken hormones as part of transition.
Also, I’m not a doctor or registered dietitian. The purpose of my blog is to share my experiences with simple intentional living and holistic nutrition. When it comes to your health and wellbeing, do your research and consult with your doctor or medical professional before making any lifestyle changes.