It's not news for the women of the Indian subcontinent. For generations, they've been well aware that papaya and pregnancy don't mix. But now researchers at Britain's University of Sussex have proven the contraceptive qualities of the tropical fruit. "Women in Sri Lanka use papaya fruit as contraceptives because they are cheap and natural," says Tharmalingam Senthilomohan. "If they want to become pregnant, they simply avoid eating them." His findings: abortion can be induced by eating unripe papaya for three consecutive days. And daily consumption of ripe fruit can be an effective contraceptive. Senthilomohan has two theories on what gives papaya its contraceptive qualities. The tropical fruit contains an enzyme called papain which suppresses progesterone, a sex hormone needed to prepare the uterus for conception and to maintain the pregnancy. Another possibility is that papain, which can be used to tenderize meat, may break down a membrane vital to the development of the fetus.