Hello,
Thanks for your consult at DoctorSpring.
If your wife is breastfeeding , and still has not had her period after delivery, chances are quite low that she might be ovulating and hence might get pregnant. Even then, you should not take a risk, and hence must ensure that you use some kind of contraception in future as you are sexually active once more.
Right now, the best measure is to take some kind of emergency contraception.
Please remember that this is not the best measure, as it should be used only in emergency desperate situations , and not as a replacement for routine regular contraception.
You can take pills such as Unwanted 72, I pill, Plan B etc over the counter. These are best taken within 72 hours of unprotected intercourse, and 2 pills should be taken 12 hours apart.
These pills should cause some kind of withdrawal bleeding within a few days after taking it. Please ensure that this is a one off incident, and you should soon visit your gynecologist for routine contraceptive advice.
Also, remember that since your wife would be having irregular cycles after delivery, you should still remember to take a urine pregnancy test 4 weeks from now, even if emergency pill was taken and withdrawal bleed occurred.
All the best.
Please feel free to ask any further follow up questions.