Hello,

If she is pregnant the birth control pills won't hurt the fetus. There is little to be seen in an ultrasound prior to about 6 weeks. I can give you some basics on how the conception cycle works. If you know the date of her previous menstruation, that can help you decide if she is telling the truth.

Most women ovulate about mid-cycle and cycles last about 28 days on average. So for the "average" woman ovulation is on day 14. The ovum lives just 24 hours after it is released from the ovary. Intercourse 3 days before ovulation to one day after are the times most likely to result in fertilization. Once the egg is fertilized, it takes another 6-12 days to make its way back down the fallopian tub and implant in the lining of the uterus. At this point the placenta starts forming and the pregnancy hormone hCG begins to be made. This also signals the other hormones not to cause a menstrual period which would eliminate the baby and the uterine lining. By this time, it is just a few days before the next period would be due. I tend to agree with your nurse friend that your girlfriend may not be telling you the whole truth.