Why do the rules exist? (dry days)

Disclaimer: As with any time I write about the specifics of fertility awareness, I’ve gotta remind you that you MUST take a class or AT LEAST read a full book on the sympto-thermal method of fertility awareness to practice it properly. Reading blog posts and downloading an app does not cut it, kapish? 

This post is part of a series: Why do the rules exist? 

Essentially, when you are using the sympto-thermal method of fertility awareness you are doing a few things:

• Checking your fertility signs.
• Charting your fertility signs.
• Applying “rules” to those fertility signs so that you know when you are inside and outside of the fertile phase of your cycle.

Knowing why the rules exist is very important because it helps you understand what rules you should never ever break if you are very strictly trying to avoid pregnancy, and what you might not care about if you are a little more on the “umm… I kinda don’t want to get pregnant, but at the same time I don’t really mind if I do get pregnant”- side of the trying to avoid scale. It also helps you understand how your hormones and cycle work better, making you a better user of the method.

Today I want to discuss the dry days rules

The first thing you need to know about the dry days rules are that they only apply to specific days. You find those days possibly a little bit differently with different sympto-thermal methods, but there are two basics.

The first is that any change in cervical fluid (from dry or your own personal basic infertile pattern) is considered a point of change into the non-dry days. The reason for this is because cervical fluid is the actual substance needed in order to facilitate sperm movement and life inside of the otherwise hostile, sperm killing, vaginal environment. Not only do you know that when you see cervical fluid sperm has a great chance of surviving until ovulation, but the presence of cervical fluid signifies that your hormonal environment has changed and ovulation is getting near (the exception being if you have a hormonal imbalance or otherwise irregular cycles, like breastfeeding, in which case cervical fluid can show up a decent amount earlier pre-ovulation). So, cervical fluid = ovulation is coming soon and sperm can now potentially survive until ovulation happens. THIS is why we use cervical fluid as an indicator of fertility and why dry days are considered infertile.

The second is a calculation based on past cycles. GASP! Past cycle calculations, aren’t those totally not kosher in the sympto-thermal method? In general, yes, but this one is only to make the method more conservative and is NEVER used as a substitute for your cervical fluid observations, which gives you information about your current cycle. This one is called the Doering rule and it is based on the earliest temperature rise in your last twelve cycles. Essentially, you subtract 8 days from your earliest temperature rise and consider that day your last infertile day even if you have not yet seen cervical fluid. If you had already seen cervical fluid by that day you would consider yourself fertile regardless of the cycle day you were on. The reason this rule exists is for the small amount of time intercourse right before cervical fluid turns fertile might happen. You have a higher probability of that never happening if you are also keeping an eye out for the calendar, as well as your cervical fluid.

Now that you know the basics of why we use certain days as dry/infertile days, why are they actually used in the ways that they are considered infertile during your cycle? 

During dry days you have two addition “rules” to apply to those days for safe time. The first is that you can only have unprotected intercourse in the evening and the second is that you can only have unprotected intercourse every other day.

The main reason both of these rules exist is to foster complete checking of cervical fluid (but I’m also going to talk a bit about theories below).

Cervical fluid needs gravity to make it’s way to your vaginal opening, as well as generally needing some muscle contractions (like you have when peeing or pooping) to get there, too. Because of this, you want to spend the day checking cervical fluid before you decide it’s “dry”. Hence the evening rule.

Regarding the every other day rule, this is because semen can interfere with your cervical fluid check, not to mention lubricant or spermicide, if used! Semen also has some prostaglandins that can foster ripening of the cervix and some people will always see some cervical fluid after unprotected intercourse.

However, both of these rules come to contention OFTEN, but the method does not seem to work nearly as well without them. You might think:

“I could just do an internal cervical fluid check and then not have to worry about checking my cervical fluid all day before unprotected…”

or “What’s the big deal about having unprotected sex everyday if I just make sure the semen is out of me and I am totally dry?”

I get it, it’s normal to question this stuff when you know the reasoning behind it. So for you skeptics and ponderers, here is some theory as to why the method just doesn’t work as well without those rules.

Regarding the evening rule, I don’t think I have seen this theorized anywhere than in my own head, so who knows, this could totally not be the reason for this rule. Estrogen levels peak in the earlier part of the day. Because of that, it’s possible that cervical fluid production is more likely to start during the daytime than the evening. Like I said, it’s only a theory I came up with, so I could be totally wrong. Let me know in the comments if you’ve noticed your cervical fluid tends to start in the morning/evening an maybe we can see if there is a trend.

Regarding the every other day rule I have seen it theorized that the successive exposure to the prostaglandins in semen can encourage a longer sticking around of cervical fluid and ripening of the cervix, potentially until the estrogen surge associated with ovulation coming soon.

Of course, these are both THEORIES, but it is important to note that the method just doesn’t seem to work as well without these dry day rules.