The birth control pills regulate your hormones and prevent the ovulation which releases the egg each month. You cannot be pregnant when there no egg available to be fertilized.
Here is the specially prescription of working: the hormone estrogen levels rise at the beginning of the each menstrual cycle. The bloody lining of the uterus (endometrium) thickens with the help of estrogen to prepare for a fertilized egg. When the estrogen level reaches the peak point, 14 days into the menstrual cycle, one or more eggs are released by one of the ovaries. This release is called ovulation.
The progesterone which is another reproductive hormone thickens the lining. After ovulation, it rises to help prepare the uterus to receive a fertilized egg. The egg travels from the fallopian tubes to the uterus. If the egg is successfully fertilized and implants itself into the uterine successfully, the pregnancy occurs.
Both the estrogen and progesterone levels drop if the pregnancy does not occur. They signal the thickened uterine bloody lining and menstruation period begins.
The birth control pills are the both estrogen and progesterone hormones’ forms. They maintain more consistent hormone levels and prevent the ovulation. If the estrogen level cannot reach the peak point, the signal cannot reach the ovary to release the egg. However, do not forget that no egg means no fertilization and pregnancy possibility. Moreover, the pills thicken the cervical mucus and sperms cannot reach the egg. By this way, it makes the uterus lining unreceptive to the fertilized egg implantation.
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