Why do birth control pills contain estrogen apex?

They increase the levels of estrogen in the body because this hormone is not related to the keeping of pregnancy, progesterone does. The hormones prevent a woman's ovary from releasing an egg during her menstrual cycle. They upset the natural progress of natural hormonal release and repress the hormones FSH (Follicle Stimulating Hormone) and LH (Luteinizing hormone) required for ovulation.