Ovulation is defined as the moment that an egg is released from the ovary in the middle of a woman’s menstrual cycle. From the age of about 11–16 to 45–55, women produce an egg each month. The menstrual cycle begins on the first day of your period, and ovulation happens about 14 days later. Individual women have different lengths of menstrual cycle, so ovulation can occur on any day between day 2 and day 40.
The timing of ovulation and sex is important if you are trying to get pregnant. The egg that is released from the ovary only lives for 12 to 24 hours and if it is not fertilised by sperm during this time, it dies. This triggers the loss of the lining of the uterus that has built up to receive a fertilised egg, and the blood loss of the next period then starts 12–16 days later.
Ovulation causes some subtle changes in your body, and if you are finding it difficult to conceive, knowing more about how you can detect your own ovulation point can be helpful. One of the key signs to look for is a change in the consistency of your cervical and vaginal mucus. During most of the month this is quite thick and a creamy white or yellow colour. During the 2–3 days around ovulation it becomes more transparent and slippery, a bit like egg white.
Some women feel a slight aching sensation in their lower abdomen or back at the time of ovulation, but it is perfectly normal to be completely unaware that an egg has just left one of your ovaries.
The surge of luteinising hormone just before ovulation causes an increase in baseline body temperature that can be measured. If you are trying to get pregnant, it is a good idea to start a diary and take your body temperature at the same time each day for 2–3 months. If you look carefully, you should be able to see a slight increase – only 1 or 2 degrees Celsius – in the middle of your menstrual cycle. If you then plot your temperature until you see a slight increase, and have regular sex around over the next few days, you may increase your chances of pregnancy.
It is also possible to buy or ask your fertility clinic for an ovulation kit to test when you are at your most fertile. These kits usually involve using a dipstick in your urine each day, so that you can detect the surge of lutenising hormone that accompanies ovulation.