When trying to conceive (TTC), your game plan may be to have as much sex as possible. But did you know that timing your intercourse can increase your odds of getting pregnant? An ovulation calendar lets women track their ovulation and pinpoint the six-day window each month when they’re most likely to conceive. Here’s everything you need to know about using an ovulation calendar to calculate your most fertile days.
Ovulation occurs “when your ovary releases a mature egg into the fallopian tube, and it moves down the fallopian tube into the uterus,” says Obosa Osawe, M.D. Your luteinizing hormone (LH) surges 24-36 hours before ovulation, triggering the egg's release. The egg survives about 12-24 hours in the reproductive tract, and if it's fertilized with sperm during this time frame, a woman can become pregnant. If the egg isn’t fertilized, it’s reabsorbed and shed with the uterine lining during your period.
Many women notice their cervical mucus becomes thinner and more slippery during ovulation; this lets the sperm move more easily through the reproductive tract. Other symptoms of ovulation may include spotting, breast tenderness, increased libido, heightened sense of smell, and mild pelvic pain. Not everyone experiences symptoms of ovulation.
Many TTC couples plan to have sex around ovulation, since “the optimal time to get pregnant is when you’re ovulating,” says Dr. Osawe. The chances are highest on the day of ovulation and the 24 hours leading up to it. But conception can occur by having unprotected sex several days before ovulation, since sperm may live in the fallopian tubes for three to five days, says Jingwen Hou, M.D., Ph.D., an Ob-Gyn specializing in reproductive endocrinology and infertility at Kaiser Permanente in Hawaii. Once the egg dissolves within 12-24 hours of release, it can no longer lead to pregnancy.
Most women with regular periods have a 28-day cycle. “If this is true for you, expect to ovulate about 14 days after the first day of your last period,” says Dr. Osawe. Women with irregular periods usually ovulate between 11 and 21 days into their cycle.
Online ovulation calculators (like this one from Parents) can help determine your most fertile days. Women with longer cycles and irregular periods – or those who want more accuracy when predicting fertility – can use ovulation predictor kits or fertility monitors. They can also chart their basal body temperature. Learn more about finding your fertile window here.
Wondering if you can conceive a girl or boy using an ovulation calendar? As it turns out, your baby’s sex may be partially determined by conception date. This idea, called the Shettles method, was first introduced by Landrum B. Shettles in the 1960s. Her book, How to Choose the Sex of Your Baby, coauthored David Rorvik, describes the theory in more detail.
Ovulation Calendar for a Boy: Y-sperm (which produces males) supposedly travels quicker through the reproductive system and has a shorter life span. Therefore couples wanting a boy should have unprotected sex close to ovulation.
Ovulation Calendar for a Girl: X-sperm (which produces females) moves slower and has a longer life span. If you have sex a couple of days before ovulation, the X-sperm will still be around when you ovulate, while the Y-sperm will die. This may increase your odds of having a girl.