She's got a loving family who is going to support her through "the crisis". Not many do.
So during that period between first contemplating sex and the lawful marriage, on one extreme, some of these young adults who may not have received a well rounded sex education or developed a healthy sexual image may engage in risky sexual behaviour, have to deal with unwanted pregnancies, become involved in cyber-bullying and sexual violence, catch STDs or worse, contract AIDS. On the other extreme, another group of women naively enter their first lawful marriage to find out that their patriarchal society/culture measures her worth primarily by her chastity yet, none of that applies to her first lawful husband and she can't expect the same of him. And some men in these societies enter their lawful marriage believing it is their right to demand that his wife be a virgin (otherwise he may choose to pay a bride price of less monetary value for her worth).
I'm playing with extremes here, but the truth is a lot of conservative parents don't have the talk of the birds and the bees and the pill and the latex condoms with their children or entertain any questions. Due to their inability to address it, they prefer schools and the Internet to bridge this gap (which in some cases work out). For one thing, conservative parents who didn't receive this lesson from their parents are mostly at a loss to sit down and talk to their curious children about something as personal and taboo as sex. And for another, it's not an easy talk to have for either party when one's cultural/ religious influences stand in the way.
Apart from the technicalities, enough emphasis is not placed on the fact that one's sexuality is a personal choice therefore one becomes solely responsible for the consequences of one's actions relating to one's sexuality. Girls are not told enough that they can say NO to sex if they are not comfortable with it or to fight back when harassed or abused; they learn from an early age to be submissive and keep quiet out of reasons like shame or guilt. Boys often watch how their fathers treat their mothers and go on to treat their wives/ girlfriends in the same way and on the negative extreme, it can lead to generation upon generation of disrespect to the opposite gender and even violence.
I think somewhere among all the extremes, there is a dimension where both male and female children can be properly educated on sex and their rights, encouraged to respect the opposite sex and be empowered to have a healthy sexual image of oneself and one's actions relating to it.
On a related note, the Internet has given a voice to many female rights activists:
https://www.facebook.com/womenbloggers
http://wbsa.wordpress.com/
Though this post wasn't really about my baby sister, I look forward to seeing her get through her term and have a healthy litter!