Ovulation

Ovulation is a process in the female body that prepares it for a potential pregnancy. It occurs when an egg, also called an ovum, is ready for fertilization. The process typically begins around the midway point in a woman's menstrual cycle. Ovulation starts when a mature egg in the ovaries is released into the fallopian tubes, where it can be fertilized by a sperm. If it is fertilized, the egg moves into the uterus, where it will develop into a fetus. Eggs that are not fertilized are shed during a woman's period. A woman is not ovulating when she is menstruating.

Background

Most female fetuses have about two million immature eggs, also known as oocytes, at twenty weeks of development. By the time of birth, however, females have lost many of their eggs. Most females are born with about half a million to one million oocytes. The eggs mature when a young woman enters puberty, which is the period when the body becomes capable of sexual reproduction. At this time, a young woman has about three hundred thousand eggs, but she will only ovulate around five hundred eggs during her reproductive years. A woman enters a stage known as menopause around her late forties to mid-fifties. This occurs when the body runs out of eggs and stops ovulating.

The reproductive hormones involved in the menstrual cycle include follicle-stimulating hormone, luteinizing hormone, estrogen, and progesterone. During the menstrual cycle, the hormones trigger the ovaries to release oocytes. Oocytes go through various stages over the course of several months. They either mature into eggs ready to be released during ovulation, or they go dormant. Many of these oocytes never reach full maturation.

Most women have two ovaries, one on the left side and one on the right. Which one releases eggs is dependent on whichever one has the most mature eggs at the time. This means that one ovary might release significantly more eggs than the other ovary. An ovary usually releases only one egg. In cases where more than one egg is released, a woman can conceive multiple fetuses, such as fraternal, or dizygotic, multiples. Identical, also called monozygotic, multiples usually result from one egg splitting and developing into more than one fetus.

When the ovaries are getting ready to release an egg, the uterine lining, the inner wall of the uterus also known as the endometrium, thickens and prepares to receive a fertilized egg. A fertilized egg is called an embryo after implantation. Unfertilized eggs disintegrate, and they are shed along with the excess uterine lining during a woman's monthly period.

Overview

Ovulation typically occurs over a ten-day period between days eleven to twenty-one of a woman's monthly menstrual cycle. The day of ovulation determines how long the menstrual cycle will last. Women's menstrual cycles vary. Typically, most cycles are between twenty-eight and thirty-two days, but they can be shorter or longer. Each cycle is calculated starting from the first day of the last period and ending on the first day of the next period. Ovulation usually does not occur on the same day of a woman's cycle each month. It can be affected by several factors, including illness, medications, stress, or even a change in a woman's normal routine.

The menstrual cycle is divided into three phases. The first is called the follicular phase, and it begins on the first day of the last period and ends with ovulation. The length of the follicular phase varies from woman to woman. During this phase, the brain releases the follicle-stimulating hormone and luteinizing hormone, which stimulate eggs to be produced in the ovaries.

The next phase is ovulation, or the ovulatory phase. During this time, the ovaries release an egg, and the body prepares for a potential pregnancy. The last phase is called the luteal phase, and it begins right after ovulation and ends either with fertilization or when the next period starts. If an egg is fertilized by sperm, it travels to the uterus where it will implant. If the egg is not fertilized, the menstrual period will begin in about twelve to sixteen days.

Ovulation is the point in a woman's cycle when she is most likely to conceive. A woman hoping to become pregnant should have sexual intercourse a few days before she, ovulates up until and including the day of ovulation. After sex, sperm can live in the fallopian tubes for three to seven days. However, an egg lives for about one day and must be fertilized within the first twelve hours of ovulation. Having sex a few days before ovulation ensures that there is a supply of viable sperm ready to fertilize the egg.

Many women who wish to become pregnant track their menstrual cycles to determine their most fertile times. While it is difficult to determine the precise day of ovulation, ovulation kits and fertility monitors can help women determine when they are more likely to become pregnant. For this reason, tracking ovulation can help women avoid pregnancy as well.

A woman will experience certain signs and symptoms prior to and during ovulation. Some of these are subtler than others are. Before ovulation, some women experience a rise in sexual desire, an increase in cervical mucus, and the softening and opening of the cervix, the lower portion of the uterus, which is tubular in shape and connected to the vagina. Some may even feel pain in their lower back or lower abdomen called mittelschmerz. Other symptoms can occur on the day of or in the days after ovulation. These symptoms include a loss of sexual desire, a decrease in cervical mucus, a rise in body basal temperature (the lowest body temperature during rest), and sore or tender breasts.

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