The patch prevents pregnancy the same way as the pill. The ovary does not release an egg to be fertilized, and the cervical mucus also thickens, making it more difficult for sperm to enter the uterus. Progestin and estrogen are released through the skin into the bloodstream.
The patch has a 99% success rate if used properly. Women wear a single patch for seven days before replacing it, giving them the convenience of not having to remember to take a pill each day. The patch offers no protection against STD’s.