Menstrual cycle

The menstrual cycle is the series of changes in the body to prepare for a pregnancy. About once a month, the lining of the uterus (endometrium) starts to thicken. Then an ovary releases an egg. If the egg is fertilized by sperm and attaches to the lining of the uterus (implants), pregnancy begins. If the egg is not fertilized or a fertilized egg does not implant, the lining of the uterus is shed. This is the monthly menstrual bleeding (also called menstruation or menstrual period) that happens from the early teen years until menopause, around age 50.

The menstrual cycle is from Day 1 of bleeding to Day 1 of the next time of bleeding. The average cycle is 28 days. But it's normal to have a cycle that is shorter or longer. For example:

• A teen's cycles may be long (up to 45 days), growing shorter over several years.
• Between ages 25 and 35, cycles are often regular. They generally last 21 to 35 days.
• Around ages 40 to 42, cycles tend to be the shortest and most regular. This is followed by 8 to 10 years of longer, less predictable cycles until menopause.

Menstrual periods usually start around age 12. But it may start earlier or later. It's common to have fewer periods between ages 39 and 51. If you are in your teens or in your 40s, you may have cycles that are longer or that change a lot. If you are a teen, your cycles should even out with time. If you are nearing menopause, your cycles will probably get longer and then will stop.

For about a week before a period, some people may have premenstrual symptoms. You may feel irritable. You may gain water weight and feel bloated. Your breasts may feel tender. You may get acne. You also may have less energy than usual. A day or two before your period, you may start to have pain (cramps) in your belly, back, or legs. Cramps can range from mild to severe. These symptoms go away during the first days of a period. And some people have no symptoms.

When your ovary releases an egg in the middle of your cycle, you may have pain in your lower belly. You also might have red spotting for less than a day. Both are normal.

You can choose from a range of pads, tampons, or menstrual cups to manage menstrual bleeding. Follow all directions included with the product of your choice.

• Pads range from thin and light to thick and superabsorbent. They protect your clothing.
• Tampons range from small to large, for light to heavy flow. You can place a tampon in your vagina by using a slender tube (packaged with the tampon) or by placing it with a finger. Tampons should be changed at least every 4 to 8 hours.
• Menstrual cups are inserted in the vagina to collect menstrual flow. You remove the menstrual cup to empty it. Some are disposable. Others can be washed and reused. Menstrual cups can be worn for up to 12 hours.

You may have to try different products to find out what is right for you. Whichever you use, be sure to change it regularly. This helps prevent leakage and infection.