Question about Birth Control Pills

[VoodooChild]

My girlfriend and I practice birth control with the pill and by withdraw. The pill she uses is the one that only allows for four periods a year. Around two weeks ago we went on vacation, and during that time she was supposed to take the pills that allow the period to come. She decided to wait a week so that she didn't have it during the trip. So she started taking them this week and has been for two days now, and her period has yet to come. She said that a few times before, she's started bleeding the day before she takes the special pills, and every other time she's got it the day after she took the first pill. Could this delay in the bleeding be because she started taking the special pills a week after she usually does? Is it normal that the period doesn't sometimes come right after taking the first pill? Or could she somehow be pregnant?

[Zazu]

My knowledge of the pharmacokinetics of birth control drugs isn't that great but I would have thought that the disruption in the normal pattern of the drug course could cause some form of internal upset which has caused her period to cease. There is also the chance that she could be pregnant. Again, the disruption to the normal pattern of administration of the birth control drug could cause suppressed production of the relevant hormones causing eggs to be released making her liable to become pregnant. Also, the 'withdraw' method is a load of crap you know. You don't need to 'fully' reach orgasm, or reach orgasm at all for that matter, for sperm to exit your penis.

In short: there's a chance it could just be down to the drugs or she could be pregnant. Best thing to do is to give a pregnancy testing kit a go or go and see your doctor.