Women are most fertile from Day 12-14 of their cycle, so avoiding intercourse or using barrier methods mid-cycle can reduce the chances of getting pregnant. This is called Natural Family Planning. On the other hand, the opposite approach – planned intercourse at the most fertile times – can be used to increase the chances of getting pregnant.

Natural Family Planning depends on the changing fertility within a woman’s monthly cycle. It also depends on an egg being released at the same time each cycle. The egg has limited opportunity to be fertilized so that it can be ready for implantation five days later. This fertilization window is about 12-24 hours after release from the ovary. Sperm lasts 3-5 days after intercourse, so timing intercourse to avoid this window of high fertility can reduce the chances of pregnancy.

To do this, you have to monitor your cycle. Your body experiences various symptoms depending on where you are in your cycle. The most common symptoms to monitor are: bleeding (the start of your period), cervical mucus secretions, and increased body temperature.

Your options are as follows:

1. 1. Count the days. Ovulation occurs fourteen days before the start of your next period, which would be Day 14 of a 28-day cycle, Day 16 of a 30-day cycle, etc. This assumes a consistent menstrual cycle.

   2. Monitor your secretions. Vaginal mucus follows a pattern throughout your cycle. Starting when your period begins (Day 1), you’ll have no mucus secretions for 3-4 days, just your normal menstrual bleeding. This is followed by scant cloudy secretions for 3-5 days. The mid-point is excessive clear, wet, stretchy secretions for 3-4 days immediately before, during, and after ovulation. This is when you’re most fertile. Then there are no secretions again for 11-14 days until your cycle restarts. 

   3. Check your temperature. Your temperature is about half a degree Fahrenheit higher (0.3°C) in the second half of your cycle than the first half. The temperature begins to rise 1-2 days after ovulation and stays up for two weeks until your period starts. Because your temperature rises after ovulation, it’s not a great predictor of when ovulation will happen – it just shows that it has already happened. After your temperature rises, your high-fertility window has passed and subsequent chances of getting pregnant are low. However, active infections (i.e. fever) can cause changes in temperature independent of the menstrual cycle, so simply catching a cold can throw off this method of monitoring.

Ultimately, how you keep track of your cycle is up to you and your husband. The best method is whichever one you’re most comfortable with and can use correctly and consistently.

Natural Family Planning is best used by highly motivated women with regular menstrual cycles whose husband is supportive of this approach to birth control. They typically don’t want to use more conventional forms of birth control for health reasons or personal choices. The couple must be able to avoid intercourse or use barrier methods on fertile days.

This method won’t work well if your cycles are irregular or you’re not interested in being militant about recording changes in your body. It also won’t work well if your husband isn’t completely on board.

The overall effectiveness can be as low as 75%. However, better results (up to 88%) are possible by using temperature to monitor your cycle rather than just counting the days from your last period. Also, there’s a learning curve. Unintended pregnancies occur more often in the first few months, before you’ve had a chance to figure out the finer points of your cycle. There are many computer or smartphone apps available to help you keep track of symptoms and intercourse days.

Advantage: your husband will never be more involved and sensitive to your cycle. Some women appreciate this, others get annoyed with the constant questioning.

Advantage: it’s inexpensive. There’s no cost, except for condoms or other barriers during the fertile week.

Advantage: no pills, no extra hormones in your body, no procedures.

Advantage: no delay in fertility when you’re ready to start trying for pregnancy.

One of the most common complaints with Natural Family Planning is that it’s a lot of work. The hassle of carefully recording all the milestones in your cycle is inconvenient. It also removes spontaneity from your sex life, or at least forces you to use another form of birth control for unplanned intercourse. The time to have intercourse with the least chance of pregnancy is during your period, which is less than ideal for many couples.

Another major disadvantage is that it’s not very effective. Although “perfect use” can have success rates near 90%, only about three-quarters of typical couples will be successful at preventing pregnancy over the course of a year.

Overall, Natural Family Planning isn’t popular. Only about 3% of women worldwide use it as their primary method of birth control.

PULL OUT

Before modern medicine, coitus interruptus was essentially the only method of birth control. It’s recorded in the Bible and other ancient texts. The “Pull Out” or “Withdrawal” method is when the penis is withdrawn from the vaginal canal before ejaculation, so the semen isn’t released inside. 

The failure rate is upwards of 20% per year with typical use, but potentially as low as 4% with perfect use. Pull Out isn’t particularly effective because a small amount of semen can leak out of the penis before ejaculation. Plus, “accidents” (failure to pull out in time) are rampant. 

Advantages: no cost, no side effects, no medications, no devices, no need to plan around timing in cycle.

Disadvantage: less effective than most other methods, requires motivation and effort at every act.

Although up to 3% of couples worldwide use the Pull Out as their primary method of birth control, this is typically because social factors (such as limited finances) prohibit other more effective methods.