Dear Doctor, My 12-year-old daughter got her first period almost three months ago. It lasted a week. However, it hasn’t occurred again. Is this normal? When does it become regular? Teta Dear Teta, The beginning of menstruation (menarche) is one of the signs of attaining puberty in a girl. It also indicates that the girl has a healthy, normal hormonal system. Menstrual cycle occurs due to the balance of the two hormones estrogen and progesterone, which are in turn regulated by the hormones released from the pituitary gland. The inner lining of the uterus becomes thick and loaded with new blood vessels. This happens in preparation for receiving a fertilised ovum, when fertilisation does not occur; this vascular layer is shed, causing blood to flow from the vagina. Usually menarche occurs around 12 to 15 years of age and menses last till menopause. However, cases have been documented, where it has occurred in even 10-year-old girls. Initially, the cycles are irregular for a few weeks to about six months. Later on they become regular. The duration of menstrual bleeding and amount of blood flow varies from person to person. Usually, cycles are from 28 to 30 days, minus one week. Some may get it on a fixed date every month, whereas some may get it at any date within a week. There may be blood loss from three to five days and even up to seven days. In between, an egg is released from the ovary (ovulation), somewhere from 14 to 21 day of the menstrual cycle (the day when blood flow starts is counted as the first day). The day of ovulation is the one when somebody can conceive if she has had sexual intercourse in those days. There is nothing to worry in your daughter’s case. Wait patiently for few months, till her menstrual cycle is set. Meanwhile, ensure that she has a good nutritious diet including much of iron and calcium, as the requirement of these two nutrients is increased during puberty. Deficiency of the two can lead to bone and joint pains and chronic anaemia, due to monthly blood loss. Also, teach her the importance of good pelvic hygiene during menstruation. Sexual desires also begin at this time of life; hence, you should educate your daughter about safe sex. If her cycles do not become regular after even six to eight months or after beginning of regular cycles, they become irregular after some time, it is necessary to investigate to exclude some disorder of pituitary or thyroid or ovaries. Chronic anaemia can also affect menstrual cycles. Dr. Rachna Pande is a specialist in internal medicine. rachna212002@yahoo.co.uk