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How do I know when I'm fertile?

How do I know when I'm fertile?

Nicole Knight, AHCJ | June 15, 2021 | Fertility Awareness
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When you're trying to conceive, it’s natural to wonder if you’re having sex at the time in your cycle when your body is primed for baby-making. But how can you know whether ovulation is fast approaching and you're fertile?

Fortunately, ovulation comes with several tell-tale signs. Read on for clues to know when ovulation is near — to help you get pregnant faster — along with pro tips to avoid fertility pitfalls with ovulation predictor kits (OPKs).

The basics of ovulation

Ovulation is when the ovary releases an egg. Ovulation happens during the follicular phase of your cycle, which is the first half of your cycle (1). 

A surge of luteinizing hormone (LH) stimulates the release of the egg — an event that usually occurs 16-32 hours after the LH surge begins. The egg then travels down the fallopian tube and, hopefully, becomes fertilized (2).

For years, people incorrectly believed that ovulation consistently occurred for the majority of women around day 14 of the menstrual cycle. Today, we know this age-old idea is misleading for many women. A major study debunking this notion pointed out that the "widely held belief that ovulation occurs consistently on day 14 of the cycle is not correct.” Only 30% of women ovulate between day 10 and day 17 of the menstrual cycle. Most women ovulate sometime between days 11 and 21 — a significantly wide range (1, 3).

Given the variability of ovulation, it’s important to be on the lookout for physical clues to help you determine when ovulation is approaching for the best chance of timing sex for pregnancy.

What are the signs of ovulation?

Changes in your cervical mucus (CM) and cervical position can tell you when ovulation is getting close, while a shift in basal body temperature (BBT) can confirm ovulation — helpful nuggets of knowledge in your trying-to-conceive (TTC) journey (1).

Here’s a quick overview of CM, cervical position, and BBT (1, 4):

Cervical mucus

CM is fluid released by glands in your cervix. The substance changes over your cycle, generally becoming more wet, clear, and slippery — like egg whites — as ovulation nears (1, 4). 

(Learn how to check your CM daily in this post.)

Cervical position

Your cervix, which sits at the base of your uterus, changes over the course of your cycle. Early in your cycle, it sits lower in your vagina, feels firm (like the tip of your nose), and its doughnut-like opening (the os) is closed. As ovulation approaches, the cervix softens, rises higher in your vagina, and the os opens (1, 4). 

(Go here for tips on checking your cervical position.)

Basal body temperature

Basal body temperature is your resting body temperature. BBT typically rises slightly after ovulation. Tracking your BBT at the same time each morning is a fast, easy, accurate way to know if you've ovulated, because you might not ovulate every cycle. More on that to come. (1, 4). 

(Learn to track your BBT here.)

You also might experience one or more of these signs of ovulation (5):

  • Mittelschmerz (dull abdominal pain on one side)
  • Higher sex drive
  • Bloating
  • A heightened sense of taste, smell, or vision
  • Light spotting

Beyond knowing the signs of ovulation to watch for, you also should know there’s a specific window of time during your cycle when you have the best chance of getting pregnant.

Find your fertile window 

According to mountains of science, nearly all pregnancies occur in a 6-day period: the 5 days before ovulation, and ovulation day itself. This time is called the fertile window (6, 7).

Your fertile window is unique to you and your partner. It's influenced by factors like the lifespan of the egg and sperm. The egg, for instance, may live only 12-24 hours after ovulation. Then it disintegrates and is swept away with your menstrual flow (1). Sperm, on the other hand, may live up to 5 days in fertile CM. Fertile CM creates a friendly alkaline environment for sperm to reach the egg (4).

Tracking your CM, BBT, and cervical position daily is a scientifically based method to identify when you're fertile. An ovulation predictor kit, which you can buy online or at the drugstore, is another popular method to see whether ovulation is imminent (1).

How does an OPK tell me when I’m fertile?

Most OPKs work by detecting LH surge in your urine. These kits are easy to use, but they also come with downsides, such as failing to detect an LH surge (8). 

LH may peak 16-48 hours before ovulation. If your peak is on the short side, there’s a chance you may miss the surge when you test OR not have enough time to have sex prior to ovulation (8). 

Research bears this out. In fact, a "significant proportion of women" miss the best window for conceiving by the time a test detects the LH surge, according to a paper in Obstetrics & Gynecology. Given this, if you’re using an OPK, consider testing morning and night to avoid missing your surge (8).

(Pro tip: The most accurate way to identify your fertile window is by tracking your continuous core body temperature to detect the subtle temperature patterns that occur 2-4 days before ovulation. Before this was basically impossible, but our new device (coming soon!) called Priya® can do this (9).)

What if I'm not ovulating?

Ovulation is, of course, essential for an unassisted pregnancy. If you don't see signs of ovulation, it’s possible you had an anovulatory cycle (10). 

Anovulation is the medical name for the absence of ovulation. Up to one-third of women with "normal menstrual cycles" are anovulatory at some point, according to the American College of Obstetricians and Gynecologists (ACOG) (10). Anovulation may be caused by stress, weight, and various hormonal issues, including pituitary dysfunction, hyperprolactinemia (overly high prolactin levels), or polycystic ovary syndrome (PCOS) (10). 

If you don’t ovulate for several cycles in a row, consider talking to your provider. They may recommend tests to determine whether you have an underlying issue to help you get the proper treatment (10).

Figuring out when you’re fertile is an essential step on your pathway to pregnancy. Arming yourself with knowledge about your fertility may bring you a step closer to getting pregnant faster.

How Not to Waste Another Month When Trying to Conceive
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