Comment by bluGill

Someone trying to get pregnant is most likely to be low risk since odds are good they have a specific partner in mind and are having enough sex that they don't care to stray. Not always but in general

There are many pregnancies that result from one night stands and those are high risk, but only rarely was pregnancy a goal.

Also HIV spreads most often from anal sex. Someone trying to get pregnant is less likely to get HIV just because of how they are having sex and so lower risk. (Not zero though, don't rely on statistics with your life of your partner has HIV)

The topic here is HIV risk. Obviously getting pregnant requires unprotected sex, but the risk of HIV is about sex with someone who has it.