Oral Contraceptives (Birth Control Pills) to Prevent Pregnancy

Oral contraceptives are hormone pills that prevent pregnancy. It is also known commonly as the birth control pill. Oral contraceptives are able to prevent pregnancy by stopping ovulation. Without ovulation, the egg cell (ovum) is not present and can therefore not be fertilized. Hence pregnancy cannot occur. Although oral contraceptives are primarily used to prevent pregnancy, it has several other uses by regulating the levels of female hormones in the body. This makes it useful for treating or at least minimizing the symptoms associated with conditions like acne, polycystic ovarian syndrome and various other causes of menstrual irregularity.

Hormones in Oral Contraceptive Pills

Oral contraceptive pills have synthetic hormones similar to estrogen and progesterone. There are two types of pills Рthe combination oral contraceptive that contains both estrogen and progesterone, and the pill that contains progesterone only. These two hormones  Рestrogen and progsterone Рhave very important effects in the female body. It essentially prepares the body for pregnancy and should pregnancy occur, these hormone levels increase substantially to sustain pregnancy. When the oral contraceptive pill is used it basically mimics a state of pregnancy that activates the same mechanisms as in pregnancy to prevent fertilization of another egg cell.

Actions of Oral Contraceptives

Elevated levels of the female hormones suppress the secretion of two important regulators of the reproductive functions – follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Without these hormones the follicles in the ovary cannot mature and rupture to release an egg cell (ovum). However, progesterone only pills also referred to as the Minipill are not as reliable in preventing ovulation. It depends on other mechanisms to prevent pregnancy should ovulation occur. This includes changing the quantity and viscosity of the cervical mucus which hampers the entry of sperm into the uterus as well as thinning of the uterine lining so that a fertilized egg cannot implant on the uterine wall.

Period while on the Pill

There are two types of pills in a 28 day pack – the active pill (21) and the placebo pill (7). Menstrual bleeding occurs when taking the placebo pills as the hormone levels gradually decrease. With a 21 day pack, menstrual bleeding will occur in the 7 days where no pill is being used. This is sometimes referred to as a false or fake period. Normally, a menstrual period occurs when the thickened inner lining of the uterus is shed since pregnancy does not occur. This thickening does not occur when using the pill. Instead the bleeding that occurs during this time is a withdrawal bleed from temporarily stopping the pill. Newer birth control pills known as extended-cycle pills may suppress this bleeding for 3 months or even one year.

Pregnancy after the Pill

Ovulation can occur as early as two weeks after stopping the pill. This means that a woman could fall pregnant at this point. However, it is advisable to wait for the first menstrual period to occur before planning conception. Some women experience what is known as period pill amenorrhea where the menstrual periods do not return despite having discontinued the birth control pill. It is not a cause for concern if the menstrual period does not return within the first 3 months of stopping the pill. After this time, however, a woman will need to see a doctor and undergo further testing to establish why the normal menstrual period has not returned. Appropriate measure may then be taken to restore the periods.

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