Read the passage below and then answer the questions.
Oral contraceptives are usually referred to as the birth control pill—or just the pill. Birth control pills contain hormones that reduce the likelihood of pregnancy. The pill is taken by mouth, or orally, and should be taken at about the same time every day. Oral contraceptives do not prevent STIs, HPV, or cervical cancer.
Birth control pills prevent ovulation, which means that there is no ovum for sperm to fertilize. The pill also thickens cervical mucus, which slows down sperm's movement into the uterus.
Doctors need to examine all women using hormone-based birth control methods because women with certain medical conditions should not take the pill. The pill is effective at preventing pregnancy if taken exactly as prescribed by the doctor. Skipping even one pill increases the chance of becoming pregnant. Some research suggests that women who use birth control pills have an increased risk of contracting STIs.
The pill comes in two basic forms—the combination pill and the progesterone-only pill.