How could she become pregnant when I withdraw perfectly?
Heather Corinna replies:My girl friend says shes not had a period for 4 weeks now. She's been pregnant once before and says apart from when she was pregnant then her periods are regular. We have had unprotected sex for about 5 weeks but she climaxes before I ejaculate witch means I never ejaculated inside her (to be on the safe side, soon as we didn't have contraception). Before I see her I always shower and clean "everywhere," so I don't she how she could be pregnant. Even with this information she is still wondering if she is pregnant. Is there any other possible way she could be pregnant?
Please understand that when any two fertile, opposite-sex partners are having genital sex where genitals meet genitals, pregnancy is always a possibility. Birth control methods and practices reduce the risk of pregnancy -- more or less depending on the method and how consistently and correctly its used -- but sparing permanent sterilization, no method removes that risk entirely.
Withdrawal, which is what you have been using, while 96% effective with perfect use, is one of the two least effective methods in typical use: only about 73%. Even that perfect use rate is low compared to most other methods of contraception.
When or if your partner reaches orgasm does not effect how effective or not withdrawal will be in preventing a pregnancy. When you shower and if you clean your penis before sex also does not make withdrawal any safer or more effective.
If your partner is, in fact, pregnant, that could be because she was one of the 4% of people who become pregnant with perfect withdrawal use each year -- pregnancies which are most likely due to people with penises just not realizing they did ejaculate or due to sperm being present in pre-ejaculate fluids, which they can be sometimes -- or one of the 27% who become pregnant with typical use, which is a whole lot of people, so it'd not be at all unusual for her to become pregnant this way. I myself am the product of a couple who used withdrawal, even though they both agree it was used perfectly.
For right now, of course, the critical issue is determining if she is, in fact, pregnant.
So, it's way past time for her to take a pregnancy test: 4 weeks past a period when you know you're sexually active, know your periods are otherwise always regular, and also are using a method of contraception which often fails (and with withdrawal, it's a particularly poor choice for younger people, who tend to be highly fertile), is a long time to wait to take a test. She can use a home pregnancy test purchased at any pharmacy, or she can go in to see her sexual healthcare provider for a test.
Since withdrawal also does not offer any protection against sexually transmitted infections, if she's not current with her STI screenings, what I'd suggest is that she see her sexual healthcare provider to get those, and that she just gets a pregnancy test at the same time, so she can take care of all these concerns with one visit. (You, as well, need to be sure you are current with your screenings: she alone getting them is only half the story.)
Whatever the result of her tests, know that if she or both of you want to prevent pregnancy as best you can in the future, it's time to take a pause from intercourse until you can both agree on one or two more reliable methods of contraception to use.
Condoms, for instance, are available just about anywhere, cheap, very easy to use, and very effective when used properly and consistently. They also carry the extra bonus of providing protection against sexually transmitted infections, a boon no other method can boast about. Or, she may want to consider a kind of hormonal method, or a cervical barrier method. If you both are enjoying using withdrawal otherwise, you might use that in conjunction with another method to boost your effectiveness: even adding a spermicide, also a method not very effective when used alone, could make a big difference in your effectiveness. Suffice it to say, having sex without reliable contraception when you don't want a pregnancy, or using a method you know or suspect isn't so great, is also really stressful. Another benefit to both of you most other methods have is less stress, which always helps a sex life.
If, for whatever reason, one or both of you either just refuses to use another method, or is somehow unable to get your hands on anything else at all, even condoms, and one or both of you does not want and/or is not prepared for a pregnancy, what's safest to do is to just hold off on sex which poses risk of pregnancy altogether, and instead, if you want to be sexual together, choose to only engage in sexual activities like these which don't pose that risk.
In the case that your girlfriend did become pregnant, here is a link for you with some advice on dealing with that: She's pregnant: what now?
And here are a few more links to better inform you about withdrawal, reproduction and birth control choices and use: