At least, in part, you shorten the fertility of a woman when you have her go to school. She can no longer get pregnant at 14, if she is getting a high school education.
Pushing people to wait until they are 30 years of age in the Western world is a big contributor why our birth rate is below replacement level. You are shortening a women’s fertility level to about 5 years before she declines sharply.
no 14 year old should skip an education just so she can have more babies. Especially in a third world country where she won’t be able to feed them.