This is a fascinating, if at times uncomfortable, subject of discussion. I come at it from the position of being a retired cop who dealt with more than enough abuse cases and as the father of a daughter who was raped at 17.
Legislation is confused and contradictory. In some Middle East countries, child marriage is acceptable. But even in more 'civiliised' countries there are huge issues. My understanding is that the minimum age for marriage in NH, USA is 13 but the federal age for buying alcohol is 21.
Here in UK, the age of consent (and marriage with parental/court consent - except in Scotland where that consent is not required) is 16 - unless the 'other party' is a teacher or some other person in authority in which case the age of consent is 18. Yet in the recent Independence referendum, 16 year olds were given the vote, and there is a move to lower the voting age to 16.. You can't drive a car until you're 17.
The age of consent varies across Europe. This summer I was in Andorra, which straddles the Pyrenees between France and Spain. The border is largely unmarked. If I was camping, a few yards either side of the border may have made the difference between legality and paedophilia.
And it gets more crazy. Suppose there is a British soldier serving overseas. He is 19. His wife (17) sends him a nude photo of herself by email to cheer him up. Legally, she is guilty of making and distributing an indecent image of a child (legal definition 18) and he is guilty of possessing it. Or, a 17 year old boy and girl exchange images of themselves legally having sex. Both could be guilty of making/sharing/possessing indecent images of children - even if they are married.
Thinking further. What about a married couple, both 17, (and their baby) choose to holiday somewhere where the age of consent is 18?
No rational or reasonable person would seek to condone child abuse or exploitation. But just thinking this issue through could cause the brain to explode - especially given (as I understand it) that highest hormone/fertility levels tend to be at a lower age than most societies accept.
A minefield, I think.