Dear Doctor, How soon can a woman expect her period after giving birth? My sister hasn’t had hers in eight months. And it shows no signs of coming, yet a friend got hers in less than two months. What is considered a normal period? Dear Molly, Pregnancy and child birth depend on the equilibrium of the two hormones, estrogen and progesterone. During pregnancy, the level of prolactin, another hormone, is also increased. This is responsible for lactation in the mother. Sucking of the baby on the breast stimulates release of more prolactin. A mother can breastfeed her baby, till levels of prolactin are adequate, hence, adequate breast milk is produced. The high levels of prolactin inhibit ovulation in this period, therefore, menstruation does not occur in this period and even pregnancy does not occur. A mother who breastfeeds her baby 24/7 is likely to get delayed restart of menses after delivery, which can be as long as 12 months. But a mother who uses formula feed for her baby can have early return of menses, maybe just within four to five weeks. Mothers of babies who sleep very well during the night may also have early beginning of menstrual cycles after delivery. This happens because the frequency of breastfeeding is less, hence, prolactin production is not stimulated. However, this is not hard and fast. Other factors also play a part in production of breast milk. These are physical and mental stress, enhanced physical activity, obesity, any chronic disease or malnutrition. Hereditary factors also determine whether a woman produces enough breast milk for long, or it is in small quantity and stops within few months. Amount of breast milk produced also depends on the quantity of fluids consumed by the new mother. Therefore, a woman can have her menstrual periods after delivery from as early as four to five weeks to up to 8 to 12 months. However, the quantity of suppression of ovulation may not be effective with passing of time, because of breastfeeding. A reduction in prolactin levels, after three to four months, increases vulnerability of a woman to become pregnant. A woman may assume that she cannot become pregnant as she is breastfeeding, the absence of menses may also be interpreted as being due to breastfeeding, but pregnancy test and even ultrasound of the uterus if done, reveal pregnancy. Therefore, a woman should be careful. After six to eight weeks of delivery, she should use some contraceptive method to prevent pregnancy. As such, breast milk is best for a baby and has numerous advantages. Hence, she should breastfeed the baby as long as possible. However, she needs to be careful to avoid a pregnancy in this period. Dr. Rachna Pande is a specialist in internal medicine.