ASK DR. A! Are Period Tracker Apps Really Accurate?

"Are period tracker apps, which are available for smartphones, accurate? I know my body pretty well and when I'm about to 'come on', so are they worth the download?"

Back in the day, girls were given little menstrual calendars to keep in their underwear drawer (either by their mom or pediatrician) when they started puberty, in order to not get caught off guard and soil clothing and face embarrassment. But, now that schools let students "opt out" of any reproductive education, more women than ever are clueless about the working of their own bodies.

I have had many highly educated women come into my office and say "my period comes on the 10th of every month". The thinking that it will arrive on the same day each month is flawed (each month does not have the same # of days) and inaccurate.

A woman's cycle is better likened to a lunar cycle. The "cycle" counts from 1st day of bleeding in a given month until the next 1st day of bleeding (most commonly 28 days, but varying by individual and over lifetime it may change).  Knowing your cycle allows better planning of your life. Once sexually active, knowing your cycle can be the difference between unintended pregnancy, panic, and peace of mind. The rhythm method is an old-fashioned birth control method (although I do not advise fertile women rely SOLELY on this method, as its efficacy is only 75%) in which a woman knows her cycle and calculates her fertile days on this basis. 

The period app is useful and accurate, as it is simply doing the thinking for you.  It counts out your monthly cycle.  So, you can look at six months, for example, and know whether it is consistent or irregular (which looking at a calendar date, as I stated, will not). For women desiring pregnancy, it tells her when she is most likely fertile.  However, this part of the app may be less accurate if the woman's cycle is irregular, her weight fluctuates, or she is on medication. When having a woman's well visit with a doctor, a woman should be knowledgeable about her cycle and whether it is changing.  Many of my patients just whip out their phones & show me the app.

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Dr. Afriye Amerson is a member of the American Medical Association and the Medical Society of New Jersey. She is currently the assistant attending at the Department of Obstetrics and Gynecology at the Hackensack University Medical Center, and the founder of La Doctora’s Angels, an awareness campaign on umbilical cord blood banking. Since 2001 she has also been in private practice at Prospect Women’s Medical Center in Hackensack, New Jersey.