MODEL RELEASED. Taking oral contraceptive. Woman about to swallow a combined oral contraceptive pill. The combined pill contains synthetic versions of the female sex hormones oestrogen and progesterone. Both of these hormones suppress ovulation. Progesterone also increases the thickness of the mucus in the neck (cervix) of the uterus, which decreases the chances of fertilisation, should ovulation occur. It also alters the lining of the uterus, reducing the likelihood of the implantation of a fertilised egg.