Pineapple ranks high on the list of fruits to avoid during the initial days of pregnancy. This is because of an enzyme called bromelain present in the fruit. When consumed in excess, bromelain has been linked to uterine bleeding and heavy menstruation. Furthermore, pineapples are also found to have uterotonic properties that can trigger uterine contractions. Now you know why this thorny wonder isn’t much of a favorite among the pregnant lot!