Why do most women get their first period around age 12 when their bodies are usually not well developed enough to safely carry a baby to term?

Question

Why do most women get their first period around age 12 when their bodies are usually not well developed enough to safely carry a baby to term?

In: 12558

Answer 1

The WHO has some [information ](https://www.who.int/news-room/fact-sheets/detail/adolescent-pregnancy) regarding adolescent pregnancy:

> Approximately 12 million girls aged 15–19 years and at least 777,000 girls under 15 years give birth each year in developing regions.

I found this [reference ](https://obgyn.onlinelibrary.wiley.com/doi/10.1111/1471-0528.12630) particularly interesting, as it gives a breakdown of outcomes for mothers in different age groups.