The Efficiency of Rhythm Method of Birth Control: How Does it Work?

The rhythm method of birth control (also known as the Ogino-Knaus method) refers to biological methods of contraception. It does not require the use of any mechanical or chemical means. It is absolutely safe and has no side effects. Unwanted pregnancy can be avoided by abstinence during the “dangerous” (fertile days) when there is a maximum likelihood of conception. However, the reliability of rhythm/calendar contraception is not as high as many people think. According to various sources, its efficiency is only from 60 to 91%.

When was the Rhythn Method of Birth Control Invented?

This technique was developed almost 100 years ago. It was invented by the Japanese gynecologist Kyusak Ogino and his Austrian colleague German Knaus. The first one calculated the optimal days for conceiving a child, and the second one (after adding some remarks) suggested using this knowledge for contraception, which was announced at the Congress of Obstetricians in 1928. Since then, more than one generation has mastered the “science” of how to be protected by the rhythm/calendar method. Nowadays, many people still use this means of contraception, despite the fact that it is outdated.

Calendar Method: How to Potect Yourself?

Many people are sure of the following: in order to avoid unwanted pregnancy, you need to refuse to have sex for a couple of days during ovulation (the release of an egg from the ovary). But in reality, this is not so. The Ogino-Knaus method is not so simple and requires consideration of several scientific facts at once.

Ovulation (the exit of an egg from the ovary) occurs in the middle of the menstrual cycle. In the vast majority of women, it lasts 28 days, which means that the egg reaches maturity and becomes ready for fertilization on days 14-15.

 Ovulation lasts from 24 to 36 hours. Conception is possible only during this period.

 The sperm lives on average 2 to 3 days, but some “long-livers” manage to cope with their “mission” even 8 days after sexual intercourse.

Thus, in order to prevent the onset of pregnancy, it is necessary to refuse to have unprotected sex not only on the expected days of ovulation but also at least a week before it.

Rhythm Method of Birth Control: How to Calculate the “Dangerous” Period?

  • Arm yourself with records of menstrual cycles over the past 6 – 12 months.
  • Identify the shortest cycle. For example, it lasted 25 days. Subtract 18. From this figure you get 7.
  • Now pay attention to the longest cycle. Let’s say, it lasted 32 days. Subtract from this figure 11. The result is 21.
  • Draw conclusions. In this example, “dangerous” days last from the 7th to 21st day of the menstrual cycle, which means that during this period you can conceive a child. The first days after menstruation and a week after the 21st day of the cycle can be called relatively “safe”.
  • Note that the rhythm method of birth control is unreliable. Ovulation can happen earlier or, conversely, later than usual.

Advantages of the Calendar Method of Contraception

  • Does not require financial costs
  • Does not require the use of any mechanical or chemical means
  • It has no side effects
  • Facilitates pregnancy planning in the future. If a woman knows the time of ovulation, she understands on which days it is easier to conceive a child

Disadvantages of the Rhythm Method of Birth Control

  • Does not protect against sexually transmitted infections.
  • Not suitable for women with an irregular menstrual cycle.
  • Before using this means of contraception, it requires long-term follow-up (from 6 to 12 months) of the cycle and pedantic recording and calculation. The task is facilitated by modern applications that can be installed on a smartphone. However, with its loss or breakage, all data will disappear.
  • With a large difference between the shortest and longest cycles, the period when you may not protect yourself is very short.
  • There is a need to abstain from sex or use additional contraception on fertile days. Refusal of sexual relations adversely affects the sexual life of a couple. And pregnancy prevention methods that can be used these days (condoms, spermicides, interrupted sexual intercourse) do not guarantee absolute protection from conception.
  • It has low efficiency. Rhythm method of birth control can’t always protect you. It is considered one of the most unreliable methods of contraception. An error in the calculations or a failure in the menstrual cycle can easily lead to an unplanned conception.
  • Women are aware of the low reliability of the method, so every delay in menstruation becomes a cause for worry.

What is the Likelihood that the Calendar Method will Let You Down?

This is a biological or, as they say, physiological, method of contraception. If a failure occurs in the body, it affects the menstrual-ovarian cycle. Inflammation of the reproductive system, a sharp change in weight, and, of course, stress can lead to violations. It is no secret that the nervous and endocrine systems are closely related to each other. So, any emotional overstrain is fraught with a hormonal jump. Ovulation can occur earlier or, on the contrary, “late”. The provoking factor maybe even insignificant at first glance reasons: climate change, relocation, deadline of a new project, conflict, etc. In such cases, the rhythm method of birth control cannot protect you. The reliability of this contraception is only 60 – 91%.

Experts believe that if a couple has been successfully practicing the calendar method for several years with regular sex life, a woman should check her fertility (ability to conceive). The “reliability” of this type of contraception can be attributed to the infertility of one or both partners.

Are There Any Other Ways of Rhythm Method of Birth Control?

In addition to the “classic” rhythm method, there is a symptothermal method for preventing pregnancy. It includes the features of all biological options for contraception (calendar, temperature, cervical).

  • A woman makes calculations: subtracts the number 21 from the shortest cycle for six months and receives the first day of the fertile period.
  • Measures basal temperature daily: three days after it falls, the fertile period ends.
  • Monitors vaginal discharge. During the release of the egg into the fallopian tube, they are abundant, transparent and viscous. After ovulation, they become viscous and thick.

This method of contraception is more reliable than the rhythm one, but it takes time, hassle, and can also let you down. If a woman does not plan a pregnancy, she should consider other methods of contraception. For example, pay attention to hormonal contraceptives. They protect against unwanted conception by 99.9%. Keep in mind that the rhythm method of birth control cannot provide you with high efficiency of protection from unwanted pregnancy.