When you know your menstrual cycle, you improve your chances of getting pregnant. The first phase starts with the first day of bleeding during your period. Your body releases hormones, like follicle-stimulating hormone (FSH), that make the eggs inside your ovaries grow. Between days 2 and 14, those hormones also help thicken the lining of your uterus to get ready for a fertilized egg. This is called the follicular stage.
The average menstrual cycle is 28-35 days. Ovulation usually happens between days 11 and 21 of your cycle. A hormone called luteinizing hormone (LH) surges, triggering the release of the egg that’s most ripe. At the same time, your cervical mucus becomes more slippery to help sperm make their way to the egg.
Women are born with about 1 million to 2 million eggs but release only 300 to 400 through ovulation during their lifetimes. Usually, you release just one each month. The egg travels along one of the two fallopian tubes that connect your ovaries to your uterus. If the timing is right, sperm may fertilize it on its way to the uterus. If fertilization doesn’t happen within 24 hours of the egg leaving the ovary, the egg dissolves. Sperm can live for about 3 to 5 days, so knowing when you are ovulating can help you and your partner plan sex for when you’re most likely to conceive.
Generally, the best chance of pregnancy is when sex happens 1-2 days before ovulation. If you have a regular 28-day cycle, count back 14 days from when you expect your next period to start. Plan on having sex every other day around that time — say, days 12 and 14. Keep in mind that having sex every day may lower a man’s sperm count. Your cycle may be longer or shorter, so an online ovulation calculator may help you figure out the likely day.
After your body releases an egg, the hormone progesterone kicks in to build and maintain the lining of the uterus. It makes your body temperature go up slightly. So taking your temperature with a basal thermometer every morning before you get out of bed can help you figure out if you ovulated. You can buy these thermometers at the drugstore. They’re inexpensive, but they aren’t as accurate as other ways of tracking ovulation.
A surge in LH triggers your ovaries to release an egg. The surge usually happens 36 hours before the egg is released. Ovulation kits check LH levels in your urine to help you pinpoint the day of ovulation. These kits, which you can buy at the drugstore, are convenient and highly accurate. You may want to test 1-2 days before you expect the surge so you can note the rise in LH.
During the second half of your menstrual cycle, the hormone progesterone kicks in to help prepare the lining of your uterus for a fertilized egg. If the egg isn’t fertilized and doesn’t implant, it disintegrates, progesterone levels fall, and about 12 to 16 days later, the egg — along with blood and tissues from the lining of the uterus — is shed from the body. That process is menstruation. It usually lasts 3 to 7 days.
If you’re overweight or obese, losing weight can boost your chances of getting pregnant. A study found that women whose body mass index (BMI) was above normal took twice as long to get pregnant as those with a normal BMI. But a drop in weight of 5%-10% can dramatically improve ovulation and pregnancy rates. Obesity can also cause infertility and low testosterone in men. Being significantly underweight can also lead to infertility.
Fertility goes down with age, especially after the mid-30s. It also lowers the chances that fertility treatments will be successful. Experts say you should talk to your doctor if you’re under 35 and have been trying to conceive for more than 12 months, or over 35 and have been trying for more than 6 months.
Studies show that sperm count and sperm movement decrease as men age, as does sexual function. But there isn’t a cutoff age that makes a man too old to father a child. One study found that it took men age 45 or older longer to get a woman pregnant once the couple started trying. If your partner is older, you may want to talk to your doctor about ways to boost your chances.
A number of things can cause infertility. The first step is for your doctor to check out you and your partner. Infertility treatments can include fertility drugs, to stimulate ovulation, and in vitro fertilization, which involves removing eggs from the ovaries, fertilizing them (shown here), and then implanting them into the uterus.
Home pregnancy tests check your urine for the “pregnancy hormone,” called hCG, that your body makes once a fertilized egg implants in your uterus. Some of these tests may be able to tell if you’re pregnant as early as 5 days before your first missed period.
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The National Infertility Association, Resolve.org: “The Menstrual Cycle,” “Tracking Most Fertile Time,” “The Impact of Environmental Factors, Body Weight & Exercise on Fertility.”
American Pregnancy Association: “Understanding Ovulation,” “Ovulation Calculator: How to Track Ovulation,” “OV-Watch Fertility Predictor,” “Pre-Conception Health for Men.”
UptoDate.com: “Evaluation of the Menstrual Cycle and Timing of Ovulation.”
The Jones Institute for Reproductive Medicine: “Fertility Tests — Ovulation,” “In Vitro Fertilization (IVF),” “Ovulation Induction (OI).”
News release, National Institutes of Health.
American Society for Reproductive Medicine: “Patient’s Fact Sheet: Weight and Fertility,” Age and Fertility: A Guide for Patients.”
Womenshealth.gov: “Healthy Pregnancy: Trying to Conceive,” “Pregnancy Tests.”
Eskenazi, B. Human Reproduction, February 2003; vol 18: pp 447-454.
Hassan, M. Fertility and Sterility, June 2003; vol 79: pp 1520-1527.
Mayo Clinic: “Symptoms of pregnancy: What happens first.”
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