Over the last three decades, contraception has become commonplace. Ease of access to many forms of birth control has allowed women to have their reproductive destinies in their own hands, to pursue higher education and professional careers, and to be able to reliably delay pregnancy until the time is right.All oral contraceptives act on the hormonal system. Many different forms of the “pill” exist, but they all work on the same principle. The pills are made up of synthetic hormones – estrogen and progestin. These synthetic hormones work together to prevent ovulation, resulting in no egg being released by the ovaries. With no egg released, pregnancy cannot occur. Pills containing estrogen and progestin also have a side-effect: a thickening of the mucous on the cervix, which hampers the attempts of sperm to enter the uterus.Deciding when to stop taking oral contraceptives when planning for pregnancy is straightforward for most women. There are certain factors, however, that should be taken into consideration in some situations. A history of irregular menstrual cycles, duration of use of the pill, and dramatic changes in weight since first taking the pill can affect your decision.Decreased FertilityThe use of oral contraceptives does not cause infertility once they are stopped. There is, however, a period of decreased fertility following their use. A recent study, published in the International Journal of Fertility, measured a 30% reduction in the chance of conceiving during the first month after stopping the pills. This change in the level of fertility had disappeared completely within three months.The results of several other high-profile studies suggest that for women taking the most commonly prescribed dosage of any of the forms on oral contraceptive, compared to women using other forms of birth control, there was an average delay in conceiving of approximately one month. The studies also revealed that in the first cycle after stopping the pill the chances of conceiving were 24%, compared to 35% for women using other forms of birth control. That represents a reduction in conception rates of about one-third for women in the first month after stopping oral contraceptives.This one-third lower chance of conceiving per cycle was shown to continue for as long as one year. While this represents only a one-month delay in conceiving compared to women who have not been on the pill, in the minority of women there can be extended delays. For these few women, the period of decreased fertility can persist for at least one year.To maximise your chances of a successful conception on your first attempt, oral contraceptives should be discontinued for three months prior to your attempts to become pregnant. This also ensures that no residue from the pills remain in your system at the time of conception. Conceiving while pill residues remain in your body causes a slight increase in the risk of birth defects. A three month period off the pill is sufficient to clear all traces of oral contraceptives from your body. During this three month period, a barrier form of contraception should be used to ensure that pregnancy does not occur earlier than planned.