However, some formulations are available that are specifically designed to provide a longer gap between periods, with active pills being taken for 84 days (12 weeks) or one year, respectively. In the second case, the active pills are taken for more than 21 days, thus reducing the number of withdrawal bleeds experienced over a year, but not stopping them altogether.Īlmost any combined estrogen-progestin oral contraceptive can be used in either of these ways. In the first type, the hormone pills are taken without a break for a year or more, which means there are no withdrawal bleeds. One is called continuous-use birth control and the other is extended-use birth control. There are two ways in which this can be done. For this reason, many scientists in the field of reproductive health have been examining the feasibility and safety of using birth control pills continuously, without monthly withdrawal bleeds. However, this phenomenon is quite different from menstrual bleeding and is not really essential for a woman’s health. This leaves time for endometrial shedding, called withdrawal bleeding. Traditional oral contraceptive pills are designed to deliver a low dose of female sex hormones, either estrogen and progesterone in combination, or progesterone alone, for 21 days, with a fourth week without any hormones. Estrogen also upregulates estrogen receptors within the cells, allowing for the dose of progesterone to be reduced. With progestin-only pills, effective contraception is possible, but the addition of estrogen adds to its efficacy by preventing follicular development, stabilizing the endometrium and perhaps preventing breakthrough bleeding, which is more common with the former. Moreover, the tubal motility decreases, hindering sperm and ovum movement through the fallopian tube and thus preventing efficient fertilization. This keeps sperm from swimming up to reach the uterine cavity and then the fallopian tubes, where fertilization occurs. Additional contraceptive effects are caused by the change in cervical mucus characteristics to become thick and impermeable.
The endometrial glands show atrophy, and the uterus is not receptive to implantation if fertilization occurs. With a combined OCP, the progesterone shows stronger activity than the estrogen, causing the endometrium to become thin but decidualized. During the luteal phase, the endometrium has already become thickened and it is now decidualized by the action of progesterone. Progesterone is not normally present at significant levels in the non-luteal phase of the normal menstrual cycle. Both together prevent the occurrence of ovulation. The progestin molecule inhibits luteinizing hormone (LH) secretion and thus keeps the LH surge from occurring. The estrogen component prevents the increase in follicle-stimulating hormone (FSH), thus inhibiting the formation of a dominant follicle. Liji Thomas, MD Reviewed by Sophia CoveneyĬombined oral contraceptive pills (OCP) act by inhibiting ovulation at the level of the pituitary and hypothalamus, via suppression of gonadotropin secretion.Ĭontraceptive pill. If you suffer from any abnormal side effects which bother you, you should always discuss them with a doctor.By Dr. These side effects are rare to very rare but they can indicate a serious condition such as an allergic reaction, a problem with your liver or cancer.
Many women do not experience any side effects while using the combined pill or progesterone-only pill but you may need to try a few different pills before you find the one which works best for you. Which side effects can the pill cause? It is difficult for your doctor or nurse to determine which contraceptive pill may cause you side effects.