Menopause

Japanese: menopause

...There is no clear age standard for late menstruation, but since cases after the age of 18 are often primary amenorrhea, specialized medical care by a gynecologist is required. Menopause can also occur abnormally early or late. Menopause before the age of 40 is called early menopause, and menopause after the age of 56 is called late menopause.

From [Menopause]

...Menopausal symptoms are not only caused by physical changes, but are often also triggered by psychological factors, such as feelings of alienation due to changes in the family environment, such as children growing up.
[Menopause]
Even though the average life expectancy of women today is over 80 years, the age at which women reach menopause (the age at which menstruation stops) has not changed much from the past, remaining at an average of 48.9 years. However, there is a large individual difference, ranging from 40 to 55 years.

From [Genitals]

…Menstruation also stops. This is the menopause. After menopause, the primary and secondary follicles and their atresia disappear completely within 2-3 years, and the entire ovary atrophies and turns into a mass of collagen fibers.

*Some of the terminology explanations that mention "menopause" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…後者の晩発月経の年齢基準は明確にきめられないが，満18歳以後のものは原発性無月経であることが多いので，婦人科医の専門的な診療が必要である。また，閉経menopauseが異常に早かったり，遅かったりすることがある。40歳以前の閉経を早期閉経，56歳以上の閉経を遅発閉経という。…

【更年期障害】より

…更年期障害は肉体的変化だけでなく，子どもの成長といった家庭環境の変化などからくる疎外感など，心理的背景が誘因となっていることも少なくない。
［閉経期menopause］
　女性の平均寿命が80歳をこえた今日でも，閉経年齢(月経が閉止する年齢)は昔とたいして変わらず，平均48.9歳である。しかし個人差は40～55歳と大きい。…