Revved...

How can you tell whether an “accidental” pregnancy is legit? 

Women intent on trapping a man with pregnancy may fake it until they can make it.

Many Pregnancy benefits that might motivate someone to get pregnant accidentally-on-purpose.
 Fulfill her dream to be a mom, seal the deal on your relationship, and get you to support her directly or through child support.

The pregnancy is intended to secure a relationship or financial support or the primary objective is motherhood.

A woman may seduce her partner when she thinks she has an increased chance of conceiving.  But then again, some women experience increased sexual arousal when they are fertile. She may just have been seductive because she was revved up by her hormones.

All in all, if you don't want children you know what to do or not to do...