Final answer:
The most common form of birth control for women in the United States today is the pill.
Step-by-step explanation:
The most common form of birth control for women in the United States today is the pill. Birth control pills are hormonal contraceptives that contain either estrogen and progesterone or progesterone alone. They work by inhibiting ovulation and thickening cervical mucus. With perfect use, the failure rate of birth control pills is only about one percent or less, but with typical use, it rises to about ten percent.