Sometimes this is logical, other times it seems like an attention grab. It is fairly common for certain communities on, for example, Livejournal to be overly sensitive to people's 'triggers' (often but not always relating to sexual assault)--any mention of violence may be censored.
Why having kids later is a really big deal. The average age of American women having their first child reached a record high of 26 years old in 2013, according to the Centers for Disease Control and Prevention's National Vital Statistics Report.
So, the chart below gives the events and their ranges. The average age for periods in the U.S. is 12.16 for black girls and 12.88 for whites. By age 11, 28% of black girls and 13.5% of whites menstruate. By age 12, 62% of blacks, and 35% of whites.