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When Should You Use an Ovulation Predictor Kit to Calculate Ovulation?

An over-the-counter ovulation predictor is the best DIY test to calculate ovulation for natural conception

Happy couple considering using an ovulation predictor kit | Tennessee Reproductive Medicine | ChattanoogaWhen a couple tries to get pregnant naturally and they don’t conceive after several months of trying, a light bulb goes off in their heads: Why isn’t this working?

As a fertility specialist, I can tell you that when you want to conceive, timing is everything.

Getting pregnant is harder than you’d think. While about 85% of couples aged 20 through mid-30s become pregnant within 12 months of having unprotected intercourse, many people desire a more precise way of knowing when to have sex.

This is when an ovulation predictor kit (OPK) comes in handy. Several terms are used for these kits, such as ovulation tracker, ovulation kit, ovulation test, ovulation calculator and fertility window calculator, but they essentially do the same thing: predict when you ovulate.

Ovulation 101

In the middle of a regular 28-day menstrual cycle, the egg is released from the ovary (a process called ovulation) and travels into the fallopian tube, where it will live up to 24 hours, ready for fertilization by sperm. Conception can occur if sperm meet the egg during that time or if sperm are already present in the fallopian tubes up to six days prior.

An ovulation predictor kit can reliably tell you when you will ovulate so you can plan to have intercourse several times in the days prior and the day of.

How an ovulation predictor kit (OPK) calculates ovulation

An OPK involves measuring how much luteinizing hormone (LH) is present in a woman’s urine. This naturally occurring hormone, which is normally produced in very low levels, surges about 36 hours before ovulation and triggers the release of a mature egg from its follicle.

Testing the urine for high levels of LH is a reliable indicator for the optimal fertility window and the chance for conception. Once ovulation occurs, the amount of LH in the body decreases, so a couple will have to wait for the next menstrual cycle to try again.

Using an OPK is part of a process called timed intercourse. It may not sound romantic to have to schedule lovemaking, but working within the maximum fertility window is the surest way to conceive without medical assistance.

If you’re concerned about your fertility or you’ve been trying to get pregnant without success, take our online fertility quiz. Check Your Fertility

When to use an ovulation kit to predict your fertility window

Before you buy an ovulation predictor kit, I recommend tracking your menstrual cycle for at least two months. Because few women experience true 28-day cycles, it’s important to get a good understanding of your own.

Write down the date of the first day of one period and then the start date of the next (and ideally the next). Count the number of days in each cycle. If there is a variance, calculate the average. Now you can approximate when the middle of your next cycle will be.

Because most women ovulate about half-way through a cycle, start using the ovulation tests a few days after your period ends. Continue to test daily until a positive result appears.

Ovulation predictor kits, such as Clearblue Digital Ovulation Test and Easy@Home 50 Test Kit, are available at drug stores, pharmacies and online. They come in digital or paper-strip models (both are reliable) and are usually packaged with 7-20 tests. The cost runs from less than $20 to more than $50 per kit.

How to use an ovulation test

  • There’s no such thing as the best ovulation test or the best ovulation predictor kit. Use a kit that fits your budget and whose instructions are easy to follow. When used properly, an ovulation tracker provides very accurate results.
  • It doesn’t matter when during the day you take an ovulation test. The important thing is that you take it at the same time each day.
  • Reduce your intake of liquids (water, tea, sodas, coffee, etc.) for four hours prior to testing so that the luteinizing hormone is not diluted. For this reason, many women take the test when they first wake up.
  • The ovulation test usually involves urinating on a test strip or filling a small cup with urine and dipping in the test strip. Follow the instructions that come with the kit.
  • Results show up in just a few minutes. Positive results often show up as two parallel lines or a smiley face.

If you don’t get a positive result on the first try, keep testing day after day at the same time of day until you do. When you see a positive result, it means that you should have intercourse as much as possible for the next three to four days.

Be sure to add the dates of positive LH results to your menstrual cycle calendar so you can start seeing patterns of menstruation and ovulation over time. Once you start seeing a pattern, you can plan to have sex up to five days prior to ovulation and for 24-36 hours after a positive result.

 Why Predictable Ovulation Is Important

When an ovulation predictor won’t work

Ovulation predictor kits (also called ovulation tracker kits) are an easy and cost-effective way to perform at-home testing. They also offer more reliable results than homeopathic measures, such as taking your temperature.

But there are issues that will prevent an ovulation predictor from helping you conceive. These include the following.

  • Irregular periods. It will be difficult to figure out when to start testing and when ovulation will occur when periods aren’t predictable. There are many possible reasons for abnormal periods, the most common being polycystic ovary syndrome (PCOS) and women should speak with a doctor if they experience this condition.
  • Uterine anomalies. A woman may not even be aware that her uterus, ovaries or fallopian tubes are damaged, misshapen or dysfunctional until she starts trying to conceive and can’t. Clinical fertility testing will help women identify any issues.
  • Ovarian cysts. Cysts can grow on the ovaries on their own or related to conditions including endometriosis. They can cause pain and may hamper ovulation and fertility.
  • Anovulation. Some women don’t ovulate at all. This happens when there is an imbalance of hormones that prevents the ovaries from releasing eggs. It is a common cause of female infertility and frequently seen in women with PCOS.
  • Male infertility. Sometimes the ovarian predictor kit works just fine; it’s the male partner who may have unknown fertility issues. He may need to undergo male fertility testing to assess any issues.
  • Unexplained infertility. This is a common cause of not getting pregnant, with up to 30% of infertile couples experiencing it. Unexplained infertility means that medical testing has not been able to pinpoint the exact cause for infertility. It does not mean nothing is wrong; there are parts of fertility that are impossible to test in a woman’s body (like how well the sperm and egg communicate, what the quality of the eggs and embryos is, and whether or not an embryo is implanting). We are often successful at helping people achieve pregnancy in spite of having an unknown cause.

At-home ovulation tests can’t tell the full fertility story

While ovulation predictors are helpful and convenient, they can’t convey the biggest pieces of the fertility puzzle, which are the quantity and quality of eggs in a woman’s ovaries as well as general ovarian and fallopian tube health.

A woman’s reproductive health and functionality frequently remain blind spots until she starts trying to conceive and can’t. Reproductive organ malfunction, malformation or damage often remain undetectable until she starts trying to get pregnant. These and other causes of infertility can only be assessed by a medical professional.

That’s why, if you have been trying to get pregnant for 12 months without success (six months if age 35 or older), or if you have any conditions that increase the chance that fertility may be challenging (PCOS, fibroids, endometriosis), I encourage you to reach out to a fertility specialist for a comprehensive work-up.

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