How do they get pregnant? Through having sexual intercourse. By being sexually active, but not taking any or adequate cotraceptive measures to protect themselves.
If people engage in penetrative sex, then pregnancy is a real possibility. It is possible to get pregnant through what is loosely termed "fooling around": sexual activity without penetration, but this is a minute proportion of cases - by and large, teenagers get pregnant because they have penetrative sex and either do not use contraception or do not use the contraception they have properly or effectively.
Why do they get pregnant? That's a deep social question. Teenagers get pregnant for a wealth of reasons - because they want to; because they have not recieved adequate sex education; because they do not understand the risks; because they are pressured not to have abortions; because they are ashamed of what happened; because they were raped; because they do not know their choices; because they were pressured into having sex and/or not using contraception - there are huge numbers of reasons.
Teenagers get pregnant because teenagers have sex. Teenagers have been having sex for thousands of years, and will likely continue to do so. To lessen the number of teen pregnancies, education - about the risks involved in sex, the reliability of contraception, how to say no, how to decide - needs to be much, much improved. [ hailebop's advice column | Ask hailebop A Question ]
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