Ovulation Calculator

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About the Ovulation Calculator

Knowing the days you are most likely to be fertile can increase your chance of getting pregnant. The typical menstrual cycle is 28 days long, but each woman is different. There are about 6 days during each menstrual cycle when you can get pregnant. This is called your fertile window. Use the calculator to see which days you are most likely to be fertile. The sections below explains the rhythm of the menstrual process in more detail.

What is ovulation?

Ovulation is when the ovary releases an egg so it can be fertilized by a sperm in order to make a baby. A woman is most likely to get pregnant if she has sex without birth control in the three days before and up to the day of ovulation (since the sperm are already in place and ready to fertilize the egg as soon as it is released). A man’s sperm can live for 3 to 5 days in a woman’s reproductive organs, but a woman’s egg lives for just 12 to 24 hours after ovulation.

Days 1 through 5

Day 1 starts with the first day of your period. The blood and tissue lining the uterus (womb) break down and leave the body. This is your period. For many women, bleeding lasts from 4 to 8 days. Hormone levels are low. Low levels of the hormone estrogen can make you feel depressed or irritable.

During Days 1 through 5 of your cycle, fluid-filled pockets called follicles develop on the ovaries. Each follicle contains an egg

Days 5 through 8

Between Days 5 and 7, just one follicle continues growing while the others stop growing and are absorbed back into the ovary. Levels of the hormone estrogen from the ovaries continue rising. By Day 8 the follicle puts out increasing levels of estrogen and grows larger. Usually by Day 8, period bleeding has stopped. Higher estrogen levels from the follicle make the lining of the uterus grow and thicken. The uterine lining is rich in blood and nutrients and will help nourish the embryo if a pregnancy happens. Estrogen helps boost endorphins, which are the “feel good” brain chemicals that are also released during physical activity. You may have more energy and feel relaxed or calm.

Day 14

A few days before Day 14, your estrogen levels peak and cause a sharp rise in the level of luteinizing hormone (LH). LH causes the mature follicle to burst and release an egg from the ovary, called ovulation, on Day 14. A woman is most likely to get pregnant if she has sex on the day of ovulation or during the three days before ovulation (since the sperm are already in place and ready to fertilize the egg once it is released). A man’s sperm can live for three to five days in a woman’s reproductive organs, and a woman’s egg lives for 12 to 24 hours. In the few days before ovulation, your estrogen levels are at their highest. You may feel best around this time, emotionally and physically.

Days 15 through 24

Over the next week (Days 15 to 24), the fallopian tubes help the newly released egg travel away from the ovary toward the uterus. The ruptured follicle on the ovary makes more of the hormone progesterone, which also helps the uterine lining thicken even more. If a sperm joins with the egg in the fallopian tube (this is called fertilization), the fertilized egg will continue down the fallopian tube and attach to the lining of the uterus (womb). Pregnancy begins once a fertilized egg attaches to the womb.

Day 24 through 28

If the egg is not fertilized, it breaks apart. Around Day 24, your estrogen and progesterone levels drop if you are not pregnant. This rapid change in levels of estrogen and progesterone can cause your moods to change. Some women are more sensitive to these changing hormone levels than others. Some women feel irritable, anxious, or depressed during the premenstrual week but others do not.

In the final step of the menstrual cycle, the unfertilized egg leaves the body along with the uterine lining, beginning on Day 1 of your next period and menstrual cycle.

If you would like to understand your menstrual cycle in more detail or still have questions, Medika recommends reading the following article The Menstrual Cycle explained, for more information.