Written by Mikayla Dalton
Fertility Awareness Based Methods (FABMs) are so varied, and each offers various tools and indicators to use for tracking your cycles and identifying your fertile window. They can be used for any family planning intention, or for tracking your health. Today, we're going to focus on how these indicators help those trying to conceive.
Basal Body Temperature
Since you’re reading a Tempdrop blog, you’re very likely familiar with basal body temperature (BBT) as a fertility indicator! But while BBT is a helpful sign to have - and it can be used alone - most often it’s combined with another tool to provide a fuller picture of your cycles. This is particularly true when you're trying to get pregnant.
Regardless of your family planning intentions, it’s important to know that BBT alone doesn’t provide an alert that your fertile window has opened. Where BBT shines is in confirming that ovulation has occurred. This is incredibly important because it will help you date your pregnancy more accurately, and know when you are pregnant (or is an early indicator to start testing). But if you want to know when your body is becoming hospitable to sperm, you need another tool in your FABM toolbox. If you are hoping for pregnancy, this can provide a more accurate, targeted time for the best chances of conceiving.
In general, multiple indicators can offer the possibility of a more complete picture of your cycle, or even be more effective at correctly identifying ovulation.
Cervical Fluid or Cervical Mucus
One of these possible indicators is cervical fluid (CF) - also called cervical mucus (CM) - an amazing biogel made up of ~95% water along with gel forming substances and various other molecules including enzymes and antibodies. It has a critical role to play in your fertility. While BBT is part of your body’s response to progesterone, which plateaus at its highest point after ovulation, fertile-type CM is your body’s response to estrogen, which rises to its highest point before ovulation. Observing and noting your body’s cervical fluid over a cycle can give you an early alert of the start of your fertile window. (Note: At-home urinary hormone tests that test for estrogen can also help provide an identification of the start of the fertile window.)
However, for some women, CM alone can seem like a fuzzy indicator. This may be especially true for women new to charting, with irregular cycles, or trying to conceive (as seminal residue may obscure observations). Depending on your chosen FABM, you may be able to see an ovulation attempt, but not be able to confirm ovulation occurred through this sign alone.
Multiple indicators can help better define the fertile window. They can also narrow down the window of ovulation itself. What's the difference? Well, the fertile window is made up of the days within your cycle that your body is receptive to conception. The ovulation window is made up of the days within your cycle within which your egg is released from the ovary.
Hormone Test Strips
There are a few types of hormone test strips commonly used in FABMS.
The first, and probably most common, is luteinizing hormone (LH) strips, sometimes called Ovulation Predictor Kits (OPKs). They can be incredibly useful for some, but less so for others. For example, they may not work with some hormonal issues such as PCOS.
Using hormone tests like LH tests or Proov PdG tests can help narrow down a fuzzy ovulation window when tracking CM, although bear in mind there’s some natural variety with these signs as well.
Ultrasounds & Blood Tests
The most reliable way to pinpoint the exact day of ovulation would be daily ultrasound. For most people, that’s somewhat invasive, expensive, and/or difficult to access! Daily blood tests have similar issues. The tools FABMs use are different; these indicators do a decent job, but they’re not super accurate in pinpointing the exact day of ovulation. For example, relative to your CM, depending on method, ovulation may occur +/-2 or even +/-3 days from your “peak day.” Using BBT, your first high temperature in a thermal shift may occur on the day of ovulation, within several days following it, and for some special people, within the few days before it!
Biology is wonderfully complex, and it’s important to find the unique set of tools that best suit your unique body, your personality, and your lifestyle. As a FABM instructor who teaches the Boston Cross Check method, I often advise a combo deal to my clients, where they choose 2+ indicators to help them know when to get busy and when to test for pregnancy.
Mikayla Dalton is a childbirth educator and certified FABM instructor in the Boston Cross Check method, which includes urine hormone tests, cervical mucus and basal body temperature tracking in its observational toolbox. She's been working as a FABM educator since 2011, and specializes in the postpartum & breastfeeding phases of use as that's a time many women find more difficult to navigate. She's also a femtech geek whose husband once commented that she looked like the Borg Queen with all her fertility charting wearables on, and her bathroom sometimes resembles a lab. She blogs at Fig Leaf Fertility. If you love this post and would like to thank Mikayla, shop Tempdrop with Mikayla's unique referral link.