Should women over 50 take prenatal vits? shouldnt they be taking like senior vits or something?

my mother in law is taking prenatal vits just b/c i am. i am 20, and going to be startin a family in a few years so i wanna get my body healthy. shes 53 or 54 and she takes them also, i think shes too old and she should be taking like centrum silver vits or something. but how old is too old to be taking prenatal vitimins?