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Finding your fertility window –
Your Cervical Fluid as a Guide

The Why;  Research says you’ll get pregnant sooner

A 2013 study found that women tracking their cervical fluid had an increased probability of pregnancy, regardless of whether or not they were using ovulation testing kits (OTK) to test for an LH surge, and regardless of how often they were having sex.  THAT IS HUGE.  What it tells us is that cervical fluid is a reliably accurate predictor, or gives enough information about your fertility window to time sex for conception.


The How, Part I; Action plan

When you go to the toilet, before your pee, wipe the opening of your vagina with toilet paper and then check out the fluid from the paper using your thumb and forefinger.


After you pee, with clean hands, slide one finger inside your vagina and similarly, check out the fluid using your thumb and forefinger.  Try stretching it out.

  1. How does it feel? Consider amount, texture, colour, elasticity.
  2. Record the data on an app or calendar.


The How, Part II;  Using the information


Cervical fluid goes through changes and is likely to look something like this, on most cycles;

  • Day 4-6: dry, scanty or non-existent
  • Day 6-8: sticky
  • Day 8-10: thin, watery and increasing in amount and becoming stretchy.
  • Day 10-14: thin, very wet, elastic and able to be stretched out.
  • Day 15-20: back to thick or sticky
  • Day 20-28: back to dry


The key takeaway is that in a normal healthy cycle, your days can be broken into three categories based on your cervical fluid:

  • Infertile days are dry, thick or sticky.
  • The maybe zone is characterised by cervical fluid that is thin and a little stretchy.
  • Your fertile days are thin, wet and elastic and are typically a few days prior to mid cycle.



The What;  The science


The secretion of fluid by the cells within the cervix (called the cervical endothelium) changes in response to the reproductive hormone cycle.

Prior to ovulation, there is a rise in estradiol, which drives an increase in the amount of cervical fluid secreted and changes the physiological make up to be thinner and more alkaline.   This is “fertile fluid”, or S-type fluid.  Fertile fluid has three main functions:

  • It helps time sex for sperm to be inside the female reproductive track, waiting for the ovum (aka egg) to be released at ovulation.
  • Supports sperm swimming up the cervix to meet the ovum.
  • It facilitates capacitation of the sperm, meaning that S-type cervical fluid is responsible for activating the last stage of sperm maturation, so the sperm is able to fertilise the ovum. That is so amazing right?


After ovulation, the reproductive cycle become more progesterone driven.  At this point cervical mucus becomes thicker and pastier and begins to functions as a blockage to stop anything else entering the cervix in case of pregnancy.


And a note – fluid vs mucus

Yup.  I’m not calling it cervical mucus.  Cervical fluid is my preferred terminology because while yes, it is secreted by mucous membranes making it technically mucus, “mucus” to me (and a handful of patients), has negative, germy connotations.  This fluid is amazing, dynamic and conception-supporting and deserves so much more than to be associated with a sneezing into a tissue.

For more info about tracking cycles for conception OR contraception, drop me a line.




Jenna x



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