Pregnancy Risk with NuvaRing & Withdrawal: Symptoms & Chances

Question
My girlfriend has been on the nuvaring for two months and it has been used correctly. We have had unprotected sex twice in the month of november while she was on her birth control and me using the withdrawl method. Now she is experiencing pregnancy symptoms...sore breasts, morning sickness. What would be the chances of her becoming pregnant while on the nuvaring and using withdrawl. What else could cause her to have those symptoms? Her period is supposed to start around the 13th of december. Thank you very much

Answer
Dear Wondering,
The chance of pregnancy while on the NuvaRing is thought to be from 2-8% in one year for a couple using it.  It's closer to 2% if it's used exactly as per directions.  Withdrawal will improve the odds a little.  So pregnancy while on the pill or ring is possible but not likely.  If she had a normal period in mid-November, it's more likely that her symptoms are not from pregnancy, since a pregnancy would barely have time to implant.   Usually pregnancy symptoms don't start until at least the time of the missed period.  Other things that can cause nausea and breast soreness are stress, viral illness, etc.  A pregnancy test will usually be positive 2 weeks after pregnancy occurs, or about the time of a missed period.