Pregnancy Risk After Emergency Contraception: A Detailed Analysis

Question
Girlfriend's period started about 6/28,
We had sex 7/13.
I pulled out and she took the Plan B pills about 30hrs afterwards.

I'm bit freaked & wonder my odds of pregnancy with the combination of post-ovulation (I think?) and the methods above.


Answer
Dear Hank,

Well, I'll get the bad news out of the way first...if she has regular 28 day cycles, the timing was actually not necessarily post-ovulation. Ovulation would have been expected approximately 7/12. A woman is most fertile the few days before, day of, and up to 24 hours after ovulation. Also, historically the "pulling out" method of birth control, in and of itself, is not very effective. The withdrawal method of birth control has an average failure rate of at least 19%. Although it can be used effectively, it is not uncommon for an unplanned pregnancy to occur when a couple uses this type of contraception without another method. This is mainly because pre-ejaculate (the little bit of semen that seeps out before actual ejaculation) can have sperm cells contained within it.

However, because she took Plan B contraception within 72 hours, the chance of pregnancy is reduced considerably. (I will assume it was taken correctly - One tablet of Plan B should be taken orally as soon as possible within 72 hours after unprotected sex. The second tablet should be taken 12 hours after the first dose.) If it is taken within 72 hours after unprotected sex, it will decrease the chance of pregnancy by up to 89%. That means 7 out of every 8 women who would have gotten pregnant will not get pregnant.

However, because Plan B will often alter/disrupt normal menstrual cycles, it should not be used as a regular birth control method. If she is having regular sexual contact, she really should consider starting a more reliable birth control method or always using condoms to minimize the chance of pregnancy.

I do apologize for the delay in answering. I suffer from migraines and have had a three day-er since returning from a mini-vacation. I hope this has helped you and answered your question. I wish you well.

Brenda