Natural family planning, or it's closely related cousin, fertility awareness methods, are methods where a couple uses subtle changes in a woman's body to determine when she is fertile, and then uses this information to time having intercourse to increase or decrease the chance of pregnancy.
What's the difference between natural family planning and fertility awareness?
Natural family planning and fertility awareness are very closely related, and sometimes used interchangeably. The term "natural family planning" is sometimes used to indicate that couples abstained from intercourse during fertile times, whereas the term "fertility awareness method" is sometimes used to indicate that barrier methods like condoms were used during fertile times. On this website, I'll use them interchangeably most of the time.
Isn't pregnancy possible at any time in a woman's menstrual cycle?
Pregnancy can only occur when an egg and sperm are in the same place at the same time. Normally, an egg is released once per menstrual cycle. It "lives" for about a day, during which it can be fertilized. If it isn't fertilized in this time, pregnancy will not occur during that cycle.
Sperm, given ideal circumstances, can survive several days in the female reproductive system. As a result, intercourse that proceeds ovulation can lead to pregnancy.
To account for the life span of the sperm and egg, we conservatively estimate that pregnancy is possible for about 5 proceeding ovulation, and 3 days after ovulation. Outside of this window, pregnancy is very unlikely.
How do couples know when the woman is ovulating?
There are a variety of symptoms that can be observed - many couples use several symptoms.
- Cervical fluid - Cervical fluid changes in quantity, color, and consistency in the days proceeding ovulation.
- Temperature - If a women records her temperature first thing in the morning, she'll notice that her temperature spikes after ovulation, and stays higher until her period.
- Cervical position - The cervix changes position throughout a woman's menstrual cycle.
Is this the same as the Rhythm Method?
No! The Rhythm Method tries to predict ovulation by assuming that it occurs on the 14th day of a woman's menstrual cycle. This is not true for most women - there's a lot of variation in menstrual cycles. As a result, the Rhythm Method is notoriously ineffective. Modern methods of natural family planning determine fertility by what symptoms a woman is currently experiencing, not what her previous cycles were like.
How effective is natural family planning for preventing pregnancy?
Natural family planning using cervical fluid and temperature observations is very effective at preventing pregnancy when used correctly, a perfect use rate of 99.4%. This means that of 1000 couples correctly using natural family planning to prevent pregnancy, 6 will get pregnant unintentionally over the course of a year.
- "The effectiveness of a fertility awareness based method to avoid pregnancy in relation to a couple's sexual behaviour during the fertile time: a prospective longitudinal study" (http://humrep.oxfordjournals.org/content/22/5/1310.long)
The effectiveness of natural family planning largely depends on how consistently and conservatively couples follow the rules. This allows couples to customize the way they use NFP to fit their circumstances. For example, a couple with very serious reasons to postpone pregnancy may use stricter rules than those used in most studies, in order to further decrease their risk of pregnancy. Another couple, happy to have a big family but preferring to space their children out, may decide to avoid only their most fertile days because they are happy with an 80% efficacy rate.
Can natural family planning help us conceive?
Can natural family planning help us conceive?
Yes! Natural family planning can help in several ways. First, knowing the symptoms of impending ovulation allows couples to make love when pregnancy is most likely to occur. Since conception is only possible a few days a month, being able to identify these days is very helpful. Charts can also reveal common problems that make it difficult to get pregnant - like not ovulating, a short luteal phase, or insufficient progesterone - which allows couples to seek medical help sooner and allows doctors to make diagnosis with more information. Finally, when blessed with a pregnancy, natural family planning gives a couple and their doctors irreplaceable information about when the baby was conceived. This information can improve the quality of care for mother and baby by ensuring that tests are given at the right time and that the due date is calculated accurately.
Tell me more!
Check out our posts on the menstrual cycle, how hormonal contraception works, and how to start using NFP. Or, go to the "Resources" tab for book and website recommendations!