This usually takes a month or two. When you do start your period, write down the date of the first day of your menstrual flow. Using the date of your last menstrual period (LMP) before a pregnancy is the easiest way to calculate your fetus's age since conception. In turn, fetal age is important to know when making a number of testing, treatment, and delivery decisions. If you do happen to get pregnant shortly after stopping the pill, don't worry. Various studies have found that oral contraception use just before a pregnancy doesn't increase the risks of miscarriage or fetal problems. In fact, women who have used oral contraception have a slightly lower rate of miscarriage than women who have not used oral contraception. Although 50% of women will become pregnant in the first 3 months after stopping the pill, many women take at least a year to conceive. This delay is most likely to affect women who have taken high-dose hormones, are age 30 or older, or have never given birth. There is no evidence that using oral contraception causes permanent infertility, however. Check out our Ebook to learn more about fertility and natural family planning.