It is still possible to get pregnant after having a baby and having intercourse without a period, because ovulation usually occurs first after childbirth, followed by the return of menstruation. The levels of estrogen and progesterone drop sharply after childbirth, and by about one week after delivery, they have already dropped to the level they were at when you were not pregnant. The timing of menstrual resumption and ovulation is affected by breastfeeding. In women who are not breastfeeding, menstruation usually resumes 6-10 weeks after delivery, and ovulation resumes about 10 weeks after delivery. In women who are breastfeeding, the return of menstruation is usually later, and in some cases menstruation does not occur during breastfeeding, and ovulation resumes on average 4-6 months after delivery. Since ovulation occurs before the resumption of menstruation, breastfeeding mothers may still be able to conceive even though they have not resumed menstruation. This is why doctors always advise women who have given birth to take care of contraception before resuming sexual intercourse until their periods return.