We've established that identifying ovulation is the key to NFP success, but how do we go about doing that? Other methods of NFP recommend tracking all sorts of things like basal body temperature, the position of the cervix, quality of cervical mucus, etc. My advice is to use whatever information is helpful to you. I could never remember to take my temperature, found it really tricky to ascertain just what my cervix was up to, and the nursing woman may not have any cervical mucus(prolactin dries it up). I can attest to the fact that, so long as I was pumping milk for Jack, I had no physical indicators of fertility and had to rely solely on tests. These tests. The ones I ordered off Amazon. There is also the Clear Blue Easy ovulation monitor(which I've used), but it's expensive and it requires the presence of a regular cycle. With the tests I use now, you can test at anytime, with or without a cycle of any kind, even right after having a baby. 
They come with handy instructions printed on each little test. Hold the stick in the urine stream for five seconds, or collect a urine sample in a disposable cup and follow the instructions on the test.
Interpreting the results of the test strip can take some getting used so, since it's a little different than using a pregnancy test. In the above picture, the strip on the top is negative for LH. The strip on the bottom is positive for LH. A positive LH test means that the LH Surge has begun and I will ovulate within 24-72 hours. Now that my cycles have normalized, my LH Surge lasts about 24 hours. While I was still nursing Matteas, my LH Surge was sometimes as long as 72 hours. That meant that I might not ovulate until three days after getting a positive LH test.
And now, a close-up. Here's how it works: the pink line on the right(the one closest to the green strip with the letters 'LH' on it)is the "control line." That line shows up no matter what, even if all you do is dip the strip in water. It's for comparison.The line that's really important is the one next to the control line, the one to the left of the control line. Depending on when in your cycle you test, you may or may not see this line show up. It's mere presence doesn't indicate a positive test; it needs to be darker than or as dark as the control line. If you did one of these tests everyday after your period, you'd most likely see something like this:
Day 7: control line only(negative LH test)
Day 8: control line only(negative LH test)
Day 9: control line only(negative LH test)
Day 10: control line only(negative LH test)
Day 11: control line and very faint test line(negative LH test)
Day 12: control line and faint test line, test line a little stronger than day 11(negative LH test)
Day 13: control line and very dark test line, test line being as dark as or darker than control line(this is a positive LH test)
Day 14: control line and very dark test line, test line being as dark as or darker than control line(still positive)
Day 15: control line and test line growing faint, test line no longer as dark as control line(negative LH test)
That's just a possibility; you may only get one positive test and the test line may fade gradually or rapidly. It will seem confusing at first, but you'll get used to it.
Some Things I Recommend
Keep a calendar. Write everything down. Symptoms, lack of symptoms, when you have sex, any possible symptoms of ovulation. Even if your husband looks extra cute, write that down. You might think nothing of it at the time, but if a few weeks down the road you get a positive pregnancy test, looking back over your notes you will say "Ohhhhh...."
So you've established a positive LH Surge, what now?
The 72-hour Method
For the beginner, I recommend that you continue testing until you get a negative LH test. Since the length of the LH Surge can vary(especially if you're breastfeeding), I recommend testing every 12 hours(once in the morning and once at night) after the first positive test. Next, it's time for some math. Numbers vary on the lifespan of an egg, and range from 12-48 hours. I like to use 48 hours so my bases are covered. Once you get a negative LH test(after establishing your LH Surge), start counting. Assume that you're going to ovulate for 48 hours. So if you get a positive LH test on Monday morning and a negative LH test on Tuesday morning, assume you're ovulating from Tuesday morning until Thursday morning. Then I like to add a 24 hour buffer, just to be safe, meaning don't have sex until Friday morning. I know women who cut it a little closer and haven't gotten pregnant, but it depends on how comfortable you are taking a risk. If you are absolutely committed to avoiding pregnancy(whatever your reason), I recommend using the 72-hour method described above. I've been using it for two years with 100% success.
Test regularly at the same time of dayFeel free to do additional tests in between, but try maintaining a regular testing time(first thing in the morning is generally easiest).
Investigate more than one method of NFPA friend of mine identified ovulation and further, that she was pregnant using the Basal Body Temperature method. I like my tests, she likes her thermometer. Find something you feel comfortable using.
I've read this whole blog, and I'm still confused
E-mail me! I've spent years researching reproductive health and would be more than happy to share anything I've learned with you. Whether you are a veteran NFP user, just starting out, or simply have questions for a friend, I believe that sharing information is key to NFP success. My e-mail address is tirzahmounsey@gmail.com
