How do birth control chemicals work to prevent pregnancy?
Birth control chemicals containing estrogen and/or progestin have several major mechanisms of action. Contraceptive mechanisms prevent fertilization; when these fail, additional mechanisms prevent implantation. • Major Pre-Fertilization Mechanisms • Prevention of ovulation. • Changes cervical mucus to provide a barrier to sperm. • Major Post-Fertilization Mechanisms • Changes to the speed at which the fertilized egg moves down the fallopian tube prevent implantation. • Changes to the (endometrium) lining of the uterus make it harder for the embryo to implant in uterus when it arrives. More about post-conception mechanisms…
Birth control chemicals which contain estrogen and/or progestin have several major mechanisms of action. Contraceptive mechanisms prevent fertilization; when these fail, additional mechanisms prevent implantation. Major Pre-Fertilization Mechanisms Prevents ovulation Changes cervical mucus to provide a barrier to sperm (probably only a minor contraceptive mechanism) Major Post-Fertilization Mechanisms Changes the lining of the uterus to block implantation of the embryo More about post-conception mechanisms Do I need to use a backup method in addition to my hormonal contraceptive? If you start the Pill, Norplant, or Depo-Provera on the first day of your period, it is considered effective right away. It takes up to seven days for the hormones to become fully effective. However, the first seven days of a woman’s cycle are already infertile, so no additional protection is required. If you start the method on any other day than the first day of your period, you need to use a backup plan for
