New methods geared to help women predict the time of their ovulation are becoming increasingly abundant with the proliferation of wearables, phone apps and DIY fertility tests.
With so much information, wading through the chatter to find the most reliable methods can be overwhelming without knowing all the facts. We’ve broken it down for you below. You'll see that some simple math and a urine test kit will do the trick. It might not be the coolest method, but it is certainly the most accurate.
Let’s start by understanding the process of ovulation. In order to conceive, a woman must ovulate; that is, an egg must be released. Knowing when that happens is crucial.
To get pregnant, you need to have sex around the time of ovulation. Your most fertile days are one to two days before ovulation and on the day of ovulation. The reason? The egg can survive for up to 24 hours after leaving the ovary, but sperm can live for three to five days. So it makes sense for the sperm to reach the fallopian tube – where fertilization occurs – before the egg does.
To determine the ideal times to have sex, you’ll first need to know the length of your menstrual cycles. The length of your cycle is marked by the number of days between the first day of full flow and the first day of your next full flow. Spotting or very light bleeding should not be counted as the first day of your period.
For women with 28-day cycles, ovulation usually occurs around day 14, plus or minus one to two days. If your cycle ranges between 27 to 34 days, you will normally ovulate between days 13 to 20. You can make these calculations yourself, but some people use ovulation predictors on the Internet or mobile apps, in which you enter the start and end dates of your last several periods. However, you should confirm with an ovulation predictor kit (OPK) you can purchase online or from a store. An OPK comes with strips that test your urine for levels of the luteinizing hormone, or LH. Prices for the kits can range from $9 for a single test to $30 for a box of 10 tests.
Many women try to predict their ovulation by taking their basal body temperatures (BBT). But this method is considered to be much less accurate than using an OPK, because many external factors can affect your BBT. Irregular sleep-wake hours, drinking coffee at night, or unusual stress can throw off your BBT. Also, by the time your BBT rises to signal ovulation, ovulation may have already occurred, and you will have missed the most fertile one to two days prior to ovulation.
When using OPKs, sometimes the first urine in the day can give false positive results because it is too concentrated. Testing is recommended with the second urine of the morning. Checking it once daily is more than enough. When LH surges, a woman usually ovulates within 12 to 36 hours of that indicator. You should begin testing two to three days before the day you expect to ovulate and continue until the test indicates that you are on the verge of ovulating. If your cycle is irregular, start testing on day 11, just to be safe. The best time to have intercourse: Two to three days prior to ovulation, day of positive OPK and the day after the positive OPK.
If you don’t have regular menstrual cycles, or you’ve used the kit during two menstrual cycles and there is no indication that you are ovulating, it may be time to see a fertility specialist. A small percentage of women have a form of LH that is not detected by the kit, but a fertility specialist would be able to order other tests to confirm whether you are ovulating regularly.
In general, the American Society for Reproductive Medicine (ASRM)1 recommends couples who have not been able to get pregnant after one year of regular, unprotected sex seek an evaluation. If you are age 35 or older, or have risk factors or concerns about your fertility, then you should see a fertility doctor at any time without feeling like you have to wait 12 months.
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Specialist in Reproductive Endocrinology & Infertility
Co-founder and Co-Medical Director of CCRM San Francisco
Dr. Jun received her M.D. from Boston University and completed her residency and fellowship in reproductive endocrinology at Stanford University. Board certified in Obstetrics and Gynecology and Reproductive Endocrinology, Dr. Jun is an active member of the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine.