Harnessing the Power of your Menstrual Cycle to Avoid Pregnancy (AKA “Natural Family Planning”)

Natural Family Planning (NFP) involves tracking your cycle to avoid sex on the days you are most fertile.  It is the most “natural” way of contraception in that it involves no hormones and no barriers like condoms.  It also helps put you in tune to your body in a way you may have never been before.  Read on for tips on how it’s done and what else you need to know!

The menstrual cycle is a powerful and beautiful thing.  While most of us aren’t particularly excited about bleeding each month, it is pretty amazing to think about all the things that have to go right in order to make this happen.  Hormones rise and fall in a perfectly coordinated dance that allows us to ovulate, build up the lining of the uterus in preparation for possible fertilization, and then shed that lining if pregnancy doesn’t occur.  So how does one “harness this power” in order to use it to prevent pregnancy?  Two words: Fertile Window.  It’s all about the fertile window. 

The fertile window is the 7 day period each month when it is possible to get pregnant.  And yes, you heard me right – there are only 7 days each month you can get pregnant when not on birth control.  So by determining these 7 days and avoiding sex during this time – viola! Avoid pregnancy!  Sounds simple but unfortunately, it’s a bit trickier than this. 

Here is what you do:

Step 1: track your cycle – with an app or a simple calendar – mark the first day of your period and all the subsequent days each month.  If you want to get fancy you can include the consistency of your bleeding – spotting, heavy, clots, light, etc.   The first day of your cycle is the first day you have a normal flow.

Step 2: determine your cycle length – you do this by counting the number of days from the first day of your period to the day before the next first day of your period. 

Step 3: determine your ovulation day – take your cycle length number and subtract 14.  For example, if your cycle is 28 days, 28 – 14 = 14.  Which means you should be ovulating on day 14.

Step 4: determine your fertile window and avoid sex during that time!  As I said, the fertile window is the 7 days each month when you can potentially get pregnant and it has to do with timing of ovulation.  This is why determining when you ovulate is key to this formula (check out our previous post on ovulation monitoring for more info!).  Sperm can survive in the reproductive tract for up to 5 days but your beautiful egg, once released, only lasts 24 hours.  Because of this you can get pregnant from sex that happens up to 5 days before ovulation, the day of ovulation, and the day after ovulation – 7 days in total.  In our example of ovulation on day 14 it means the fertile window would start on day 9 (5 days before ovulation) and end on day 15 (1 day after predicted ovulation).

So this all sounds great and amazing right?!?

Unfortunately, the downside is that it’s not perfect and you can’t always predict with 100% accuracy when you’ll ovulate.  This means there can be mistakes or mishaps which is why with “typical use” natural family planning only prevents about 75 to 90% of pregnancies.  It also really only works in women who are having regular periods.  So if your period is irregular this method is definitely not advised. 

Interested in trying it out?? Check out these apps to help get you started! Clue, Flo, Glow, Ovia

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