In a recent article I posted, I listed some of the common causes for anovulatory cycles (in which ovulation does not occur), and discussed why some women who are anovulatory still experience bleeding that seems like a menstrual period. If you read the article, you know that most women will experience anovulatory cycles at some point in their lives, whether it be due to breastfeeding, coming off the Pill, stress, hormonal imbalances, lifestyle factors, or impending menopause, among other causes.
For women who experience anovulatory cycles and want to avoid pregnancy, using FAM as birth control can be a little tricky, since you don't experience all of the fertility patterns that define the 4 rules of using FAM as birth control. In this case, you need to apply the rules of using FAM as birth control as if you were continually in the pre-ovulatory phase until you experience a temperature shift (confirming that ovulation did occur). This is because even though you may not have ovulated for several cycles, you COULD ovulate at any given time. So, even if you think you’re not going to ovulate, you need to assume that you might. Tracking your BBT throughout your cycle will allow you to confirm if ovulation DOES occur (you'll observe a sustained Temperature Shift). (Note: admittedly, if you experience really long cycles without seeing a BBT shift, taking your temperature every morning can be tedious. In this case, you can wait to take your temperature until you note any changes in your cervical fluid from dry/sticky to wet/more fertile. You can also check for cervical changes if you’re uncertain about changes in your CF).
In Taking Charge of Your Fertility, Toni Weschler explains that women with anovulatory cycles often experience a Basic Infertile Pattern (BIP) of cervical fluid. This pattern is usually different than the ovulatory pattern of CF changes (dry-->sticky-->creamy-->eggwhite and/or watery-->back to sticky/dry). Some women will be dry day after day, some will experience sticky CF each day, and some will experience a combination of dry and sticky days. To establish your BIP, you need to carefully observe and track your cervical fluid over the course of two consecutive weeks.
In the chart above, the woman established her 2-week BIP as sticky. If all of the days in the two week period were dry, her Basic Infertile Pattern would be dry.
After two weeks of charting, you’ll have established your Basic Infertile Pattern. Then, you can apply the following two anovulatory rules of using FAM as birth control:
Anovulatory Rule #1: Unchanging Day Rule: If your 2-week BIP is consistently dry or the same-quality sticky CF, you can consider yourself infertile the evening of any dry or unchanging sticky day. If your BIP is a combination of dry and sticky, your risk of getting pregnant from unprotected sex on a ‘sticky’ day is slightly greater than on a dry day - so if you’re new to FAM, it’s recommended that you consider yourself infertile ONLY on dry days. And, if you do choose to have unprotected sex on your sticky BIP days, you should check for wet cervical fluid at the os (opening to the cervix) before doing so. Keep in mind that if you do have unprotected sex, semen can mask your CF reading, and in this case you might need to consider yourself potentially fertile. Doing Kegels exercises after sex will help to eliminate the semen from your vagina.
You can continue to apply your two-week BIP and the Unchanging Day Rule so long as you don’t experience any changes in your cervical fluid pattern. So, if your cervical fluid remains dry and/or sticky over the course of a month, you can apply this rule for that whole time period. If you experience a change in your BIP (for instance, from dry to sticky) that lasts for two weeks, that change then becomes your new Basic Infertile Pattern, from which you have to note any changes in your cervical fluid. You can consider yourself infertile in the evenings until you experience more fertile-quality CF or bleeding/spotting.
Because days 20-22 of this woman's cycle continue to follow the BIP of sticky, she is safe to have unprotected sex on these days. If her BIP were dry, and days 20-22 were also dry, she would be safe to have unprotected sex on these days.
As soon as you experience a change in your cervical fluid from dry/sticky to wetter (creamy, eggwhite, or watery), you need to apply Anovulatory Rule #2.
Anovulatory Rule #2: Patch Rule: As soon as you see a change in your cervical fluid/Basic Infertile Pattern, you need to consider yourself fertile until the evening of the 4th consecutive non-wet day after your Peak Day (the last day of fertile/wet cervical fluid before your CF goes back to dry/sticky). Once your CF goes back to your BIP, you can go back to applying the Unchanging Day Rule until you experience changes in your CF again. Some women may experience several ‘false peaks’ during a cycle in which their cervical fluid builds up to eggwhite/watery and then goes back to being sticky/dry. In this case, you need to apply the Patch Rule and assume you are fertile every day you experience wet cervical fluid, just in case ovulation does occur.
On Day 23, this woman experienced creamy CF, indicating that she is potentially fertile. She must wait until 4 days after her Peak Day and her BIP has resumed to have unprotected sex again. She is considered fertile from Day 23 through the evening of Day 28. On Day 31, she experienced creamy CF again, and on day 33 experienced eggwhite CF, indicating that her body might be gearing up to ovulate. But because her temperature remained in its lower range, she can confirm that ovulation did not occur. However, she is considered fertile from Day 31 through the evening of Day 37. She is safe to have unprotected sex on the evening of day 37, 4 days after the Peak Day and once her BIP of sticky has resumed.
A note on anovulatory bleeding: Because anovulatory bleeding is not a true menstrual period in that ovulation did not occur 12 to 16 days prior to the bleeding, you have to consider yourself as potentially fertile on days that you experience anovulatory bleeding. This is because the bleeding could be due to ovulatory spotting or the start of hormonal activity gearing your body up for ovulation.
On your chart, you can choose to start a new cycle each time you experience anovulatory bleeding, or you can chart it as one long cycle with intermittent periods of bleeding. But until you can confirm ovulation 12 to 16 days prior to bleeding, you have to consider yourself potentially fertile during phases of bleeding.
So in summary, the most important thing to take note of during anovulatory cycles is any change in the quality of your cervical fluid. As your body gears up to ovulate, you will likely start to experience more patches of fertile cervical fluid before ovulation occurs. Once this happens, you should monitor your BBT and cervical changes to see if ovulation does occur. Again, if you’re new to FAM or uncertain about your Basic Infertile Pattern, you should take a conservative approach and consider yourself infertile only on the evenings of days that you experienced no cervical fluid.