Input (grade 13): COCPs provide effective contraception from the very first pill if started within five days of the beginning of the menstrual cycle (within five days of the first day of menstruation).
Output (grade 11): COCPs can provide effective contaception, if the first pill is taken no later than 5 days after the start of menstruation. If the treatment is started at any other time in the menstrual cycle, COCPs can not provide a safe means of contraception for the first 7 days of use.