Natural family planning (NFP) is also known as fertility awareness and involves the monitoring of different signals your body gives off as a sign of ovulation. In doing this, many people decide to choose NFP to help aid the process of conception.
However, how reliable is NFP when used for contraceptive purposes?
To understand this fully, we would have to understand the menstrual cycle…
ABOUT THE MENSTRUAL CYCLE
The menstrual cycle consists of several processes, all governed by changes in hormone levels. The lining of the womb called the endometrium thickens and becomes more vascular. This is to allow any fertilised egg to have somewhere to implant into and have a supply of nourishment.
When an egg is not fertilised, this thickened layer is not needed and therefore sloughs off – this is your menstrual bleed.
The menstrual cycle is measured from the first day of your period, up until the day before the start of your next period. The length of this period varies from person to person, however on average this lasts between 21-40 days (1).
During this cycle, the process of ovulation takes place. Ovulation occurs when hormone levels surpass a threshold, causing one of your ovaries to release an egg. This can occur around day 14 of an average 28-day cycle but can be anything between 10-16 days before your next period, depending on your cycle length.
FERTILITY WINDOW
All the above means that if you have between sex 5 days before, to 2 days after ovulation, it is possible to get pregnant within that time. Still, this is quite a narrow window, requiring frequent sex with your partner throughout your cycle to heighten your chance of conception.
Each month, women under the age of 30 have a 20% chance of becoming pregnant, with this declining to a 5% chance in those aged 40 (3).
This is also dependent on one’s general health, reproductive health and how often you have sex, with every 2-3 days when trying to conceive being optimal.
HOW DOES NATURAL FAMILY PLANNING WORK?
NFP works by using what you know about your cycle as a form of contracteption, where you time when you have sex, and when you avoid it, based on different fertility indicators to predict when ovulation takes place (4):
Calendar based method (a.k.a. rhythm method) – this is when the menstrual cycle dates are tracked and monitored, focussing around the suspected time of maximum fertility – around day 10-16 days.
However, this method isn’t suitable for everyone given the high variability of cycle length between individuals. In addition, if your menstrual cycle isn’t regular each month, it can be hard to pinpoint when exactly your fertility window is based on dates alone (5).
Cervical mucus method (a.k.a. ovulation method) – this is when the mucus produced by your cervix is monitored, with keeping a note of how it looks each day to pinpoint when ovulation may be under way. Usually, this mucus serves to lubricate the vagina, as well as offer some protection from infections.
Throughout the menstrual cycle, hormones fluctuate causing changes to the amount, texture and appearance of this mucus. It can go from a dry, sticky texture which can be white or creamy in colour, to a stretchy, slippery texture which is clear in colour (quite similar to a raw egg-white consistency!).
When it is ‘egg-white cervical mucus’, this can be a sign of ovulation, as this consistency supports the sperm in their journey to fertilise the egg (6). So, , it can be an indication that you are in your fertile window. This is not always a guaranteed sign however!
Basal body temperature (BBT) method – this method involves measuring your temperature daily when you’re fully at rest. This would typically be first thing in the morning, before you have even gotten out of bed. Ovulation is thought to cause a slight rise in your body temperature by 0.5-1˚ (8).
When this stays elevated for three days or more, ovulation has most likely occurred. However, it is important to remember that you are most fertile a couple of days prior to this rise in BBT, and sperm can live longer in the reproductive tract.
Therefore, this method helpful to know that you should have sex now, when you are trying to conceive. If you want to avoid pregnancy, make sure you aim to only have sex 4 days after this BBT rise until the 1st day of their next menstrual bleed.
Disadvantages of this method are that you need to be totally consistent, so you have to ensure you have at least 3 hours uninterrupted sleep, and take your temperature using the same method at the same time each day when you wake up for the most accurate results. As you can imagine, this method takes the most organisation!
Symptothermal method – this method combines more than one method (usually cervical mucus and BBT) offering an increased reliability of results. It may involve a specially purchased thermometer and an app to combine the information and predictions.
SO, IS NATURAL FAMILY PLANNING USEFUL AS A CONTRACEPTIVE METHOD?
NFP is used as a hormone-free option for contraception. Although this is good for people who can’t tolerate the side effects of hormonal contraception, like the pill, there are several downsides to this approach.
Most importantly it is not a reliable method of contraception compared to the other methods – with 86-93% effectiveness, this means that there is an up to 14% failure rate with typical use (9).
It requires consistency and organization, and also is a less spontaneous approach. So if you like to live in the moment, enjoy fun nights out and don’t have a regular partner, it may be more difficult to use this technique.
It is also good to remember that there are several other hormone-free options which are more effective at preventing pregnancy like: condoms, the copper IUD , the diaphragm and male and female sterilization.
If you are still keen to go ahead with NFP as your form of contraception, here are some tips:
- Monitor and document your cycles for months before relying on NFP as a method of contraception. This includes getting to know your cycle length, cervical fluid changes unique to you and become consistent in measuring BBT
- Use condoms during these times if unable to abstain completely as 1 in 4 people using NFP will get pregnant (5)
- Consider combining multiple methods of tracking your cycle, to increase the accuracy of predicting your fertile window and set reminders on your phone to ensure you track all the required information each day.
NFP is more useful in trying to conceive as opposed to contraception, so if pregnancy is unwanted do use other methods of contraception – talk to your GP or sexual health provider for more information.
REFERENCES
4. Urrutia RP, Polis CB. Fertility awareness based methods for pregnancy prevention. BMJ. 2019;366:l4245.
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Great article to read source. Thank you for sharing this info.