| No, another contraceptive method is not needed to prevent pregnancy. Combined hormone birth control pills work primarily by preventing ovulation — the release of the egg from the ovary. If the pill is taken daily as prescribed, eggs will not usually be released. Pills also work by thickening the cervical mucus. In the rare instance that an egg is released, the thick cervical mucus will prevent sperm from entering the uterus. An egg can only live up to 24 hours. In the very unlikely event that the egg is released on the day the last active pill is taken (Day 21), the cervical mucus will prevent fertilization.
The effect of hormones taken during the 21 active pill days continues while the non-active reminder pills are taken. This means that fertilization does not take place at any time during the 28-day cycle in which the pills are taken — even during the time that reminder pills are taken and menstruation occurs. | 
