The birth control ring is a thin, flexible ring about five centimetres in diameter that a woman inserts into her vagina herself. The contraceptive ring is prescribed by a doctor after the woman has undergone a medical examination including her blood pressure.The contraceptive birth control ring contains a combination of two hormones, oestrogen and progesterone, like the oral contraceptive pill. The ring slowly releases the hormones throughout the vaginal wall to the bloodstream to prevent ovulation. The vaginal ring hormones may also cause a thickening of the cervical mucus and a thinning of the uterine wall.The woman inserts the contraceptive ring into the vagina on the first day of her menstrual cycle or before the fifth day, and the ring remains in place for three weeks in a row. In this way the ring is again comparable to the combined contraceptive pill, with a ring-free week after three weeks of using the ring.At the end of the third week, at about the same time of day on the same day as first inserted, the woman should remove and dispose of the vaginal ring, and her withdrawal bleed should start within a few days.At the end of the fourth week, the woman inserts a new contraceptive ring on the same day as the last one was inserted, even if she is still bleeding, and the process begins again.Another form of contraception such as condoms should be used for the first seven days when a woman first starts using the birth control ring if she has not used any contraceptive previously, because the hormones do not take effect immediately.The contraceptive ring is held in place by the vaginal muscles so is unlikely to fall out. However, should this occur, the vaginal ring should be rinsed in cool water and reinserted within three hours. The ring can be left in place while swimming or exercising and during sexual intercourse. When in place, the ring usually cannot be felt.Possible side effects include irregular menstrual bleeding, nausea, dizziness, headaches, breast tenderness, mood changes and vaginal irritation or discharge.The birth control ring does not protect against sexually transmitted infections.Often the choice of using the birth control ring for contraception is a couple’s decision. The woman should be comfortable with inserting the contraceptive ring into her vagina, and her partner should be comfortable with the device being there.As the woman does not have to remember a daily commitment to contraception, the birth control ring may well suit shift workers or women who travel and cross various time zones. However, she must remember to remove the ring contraception after three weeks and to replace it a week later, or it loses its effectiveness.In terms of returning to fertility, return of ovulation is likely to occur after 12 days of the ring being removed. The ring birth control is a very effective method if used correctly.