How Many Days Can a Woman Become Pregnant?

Pregnancy and the Menstrual Cycle

A woman is most fertile, and therefore most likely to get pregnant, during ovulation and on the two to three days prior to ovulation. However, her likelihood of becoming pregnant increases and decreases depending on where she is in her menstrual cycle.

If you are trying to get pregnant, it is important to pay attention to where you are in your menstrual cycle. The first day of your period is considered day 1 of your menstrual cycle. The average menstrual cycle is 28 days, though it can vary between 23 and 35 days for some women.

Around days 7 to 11, your body begins preparing for an egg to be fertilized, and pregnancy to take place.

Ovulation takes place 12 to 16 days from your next expected period (or about two weeks into your menstrual cycle), according to the American Pregnancy Association. Having sex during this time period increases your likelihood of getting pregnant.

Ovulation: Peak Time for Getting Pregnant

You have the greatest likelihood for getting pregnant during the two to three days before ovulation. Ovulation happens when a mature egg is released from your ovary and pushed down your fallopian tube. This means it is available to be fertilized.

If you have a 28- to 32-day menstrual cycle, ovulation can take place between days 11 to 21 However, every woman's cycle is different. The APA recommends using an ovulation kit or fertility monitor to determine whether you are ovulating, because this is the single greatest factor in becoming pregnant or preventing pregnancy.

One way to measure if you are ovulating is to check your basal temperature. It goes up 1/2 to 1 1/2 degrees during ovulation, and can be measured using a basal thermometer.

Getting Pregnant While On Your Period

The chances of getting pregnant from having sex while on your period are low, but it is not impossible.

Sperm can live in your body for three to five days after sex---which means pregnancy could occur from sex that takes place during your period if you were to ovulate in the several days following your period, according to the APA.

Other Factors in Getting Pregnant

Though time of the month is the most important factor in determining whether you will get pregnant, lots of other factors play a role. Being in good health, including maintaining a healthy weight and eating a healthy diet, help determine whether or not you will conceive. Having sex regularly also increases your chances of getting pregnant.

Various outside factors may make it more difficult to get pregnant, as well. According to the American Society of Reproductive Medicine, smoking has a negative impact on fertility, and smokers may find it harder to get pregnant compared to nonsmokers.

What you consume can also affect your fertility 2. Eating dairy, lean protein, fatty fish and oysters may help you conceive, according to Heidi Murkoff, author of "What to Expect When You're Expecting." Other foods, prescription drugs, over-the-counter medicines and herbal remedies have been known to delay or prevent women from conceiving 2. If you are trying to get pregnant, you should ask your doctor about any medications you are taking, and about which foods to avoid.