Why is this? Apparently, it has to do with where women live. A FertilityCare Educator (teacher of teachers) explained that she was once supervising two new practitioners (Creighton teachers). One practitioner had clients with perfect charts. Every single chart looked like the textbook cycle! (The Educator almost didn't believe her.)
At the same time, the other practitioner had messy, long, confusing, patchy cycles that needed loads of help, management, and doctor help to understand. The clients of both practitioners were all around the same age and demographic (the typical NFP user). The only difference: the clean charts were from rural North Dakota, and the nasty charts were from New York City. The Educator attributed the difference to pollution.
This scared me.
There are certainly other factors at work in this anecdote. Even so, this needs more research, because this could mean the beginning of the end of mucus based fertility awareness methods. If people can't make valid observations and be confident in their own interpretations, how can they use their fertility to plan their family naturally? I feel like I'm putting on an aluminum foil hat, but it's the truth: if we can't rely on observations and sensations, we can't use methods like BOMA or CrMS.
Even if the health of our environment is only one factor in the health of women, I would feel more motivated to care for it to help families use NFP. Meanwhile, more research is needed to discover how much pollution contributes to cycle irregularity. (I've put it on my list of research projects to do.)
If you're a couple using NFP, you know it's not easy! If you think NFP is a good thing (and that it's already hard enough, thanks), you may want to be more earnest about good environmental stewardship.