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Natural Family Planning

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Last Update: July 24, 2023.


Natural family planning is the utilization of fertility awareness to either prevent or achieve pregnancy. In the United States, approximately 1% of women utilize natural family planning methods for contraception[1] Worldwide, its use reaches about 3.6%.[2] There are numerous options available to individuals and couples who desire family planning, and natural family planning is unique in that it can be utilized both as a conceptive and contraceptive option. As a contraceptive option, natural family planning has a typical failure rate of 24%[3] 

When counseling patients regarding natural family planning, it is important to understand the patient's motivations for choosing this method and allow enough time to ensure adequate comprehension of this method’s complexities.

Issues of Concern

The physiology of the menstrual cycle and the periodicity of fertility are the basis for natural family planning. The various hormonal changes before and after ovulation lead to detectable, identifiable physical changes. After ovulation, the ovum is only viable for about 12 to 24 hours. Sperm can only survive in the genital tract for approximately 3 to 5 days after ejaculation. Combined, all these allow a couple to identify the so-called “fertile period.” Generally, a woman is fertile from 5 days before ovulation to 24 hours after.[4] If a couple is utilizing natural family planning to prevent pregnancy, they should avoid intercourse during the fertile time or use alternative contraceptives such as condoms during fertility.

Progesterone gets released from the corpus luteum following ovulation. One effect of progesterone the hypothalamus results in an increase in body temperature. If a patient tracks her basal body temperature with an oral thermometer, she can then identify when a sustained rise of about 0.5 degrees Fahrenheit occurs. This increase roughly correlates with ovulation. Identifying this day of the cycle (approximately day 14 of a 28-day cycle, where day 1 of the cycle is day 1 of menses) will allow a patient to either avoid or target ovulation in future cycles. For accuracy, patients must take their temperature before rising in the morning; this includes getting up to use the restroom, eating, drinking, brushing teeth, etc.

Cervical secretions are also affected by the hormonal changes of the menstrual cycle. Before ovulation, the developing follicle produces estradiol, which in turn facilitates cervical mucous that is hospitable to sperm capacitation (maturation) and sperm passage through the cervix. This mucus is clear, wet, abundant, and stretchy (so-called “egg white mucus”). It appears about 3 to 4 days prior to ovulation and continues to be present until immediately after ovulation. After ovulation, progesterone produced by the corpus luteum leads to changes in cervical secretions, which make them inhibitory to sperm migration and capacitation.

The increase in estrogen before ovulation causes an increase in sodium chloride in mucus. This release occurs in both cervical secretions and saliva. This increase in sodium chloride is observable under microscopy, where crystallization leads to arborization or “ferning.”[5] Estrogen also changes the character of the cervix itself. Under the influence of estrogen, during the period of fertility, the cervix is more open, soft, high, and straight.[6]

There are several methods of natural family planning:

Standard Days: This is a calendar method which determines fertility using the probability of pregnancy relative to ovulation and that ovulation happens near mid-cycle. The method is simply to avoid unprotected intercourse during cycle days 8 to 19. Standard Days is the easiest method to teach, and it requires the fewest days of alternative contraception or abstinence. Only women who have menstrual cycles that are 26 to 32 days long are candidates for this method.[7] The typical user pregnancy rate of the Standard Days Method was approximately 12 per 100 women per year in one clinical trial.[8] With correct use, the pregnancy rate was less than 5 per 100 women per year.

Billings and Creighton Methods: These two methods utilize observation of cervical secretions. The Billings Ovulation Method is the oldest of these. The Creighton Model, which is newer, requires women to score their secretions based on a multi-characteristic scale. Secretions should be observed several times a day, for example, before each time a woman urinates. Fingers or toilet tissue may be used to collect cervical secretions. If preventing pregnancy, intercourse should be avoided during menses, on preovulatory days after days with intercourse (to avoid confusion with semen), on all days secretions are consistent with ovulation, and until four days after the last day of wet/ovulatory secretions. Multiple classes or instruction sessions are recommended if these methods are being utilized to ensure adequate ability to recognize, record, and interpret secretions.

Two Day Method: This method is also based on cervical secretions and is similar to the above. The main difference is that the presence or absence of secretions alone is considered sufficient for the identification of the fertile period. Patients are recommended to avoid unprotected intercourse every day that secretions are present, as well as on the first day after. In one prospective study of the Two Day method, the pregnancy rates were 3.5 per 100 women per year for correct use and less than 14 per 100 women per year for typical use.[9]

Symptothermal Method: This method is multimodal and combines awareness of cervical secretion changes with basal body temperature monitoring. The presence of transparent, slippery, stretchy mucus is the main indicator of the start of the fertile period of the menstrual cycle, and the elevation in basal body temperature is considered the end of the fertile period. Patients should monitor their secretions several times a day, take their temperature each morning, and also check the way the cervix is positioned and feels. Patients should avoid unprotected intercourse every day that secretions are present, all preovulatory days after days with intercourse, and until three days of higher temperatures follow six days of lower temperatures or four days after the last wet secretions (whichever is later). Similar to the Billings or Creighton Methods, users of the Symptothermal Method may require several instructional sessions. Typical use failure rates for the Symptothermal Method in some studies were 13 to 20 per 100 women per year, and correct use rates were 2 per 100 women per year.[10][11]

Marquette Model: This method combines the monitoring of cervical secretions with the additional option of using an electronic device to assess fertility further. The device measures the levels of estrogen and luteinizing hormone (LH) in the urine. Because estrogen levels rise prior to ovulation, and a surge of LH triggers ovulation itself, the device may assist users in determining their fertile windows.

Other devices can be utilized to identify whether a patient is fertile. Some devices use miniature microscopes to observe the ferning of saliva or cervical mucus to determine whether ferning is present. Some handheld devices assist in measuring cycle length and correlating the cycle day with basal body temperatures.

Lactation Amenorrhea Method: Unlike other forms of natural family planning, the lactation amenorrhea method of pregnancy prevention relies on a lack of ovulation in the postpartum period when meeting certain criteria. Women must be exclusively breastfeeding, and they must be feeding at least every four hours in the day and every six hours in the night. This method is only usable for the first six months after delivery, and the patient must not have restarted menstruation. If the patient meets all of these requirements, the effectiveness of this method for contraception is up to 92 to 100%.[12]

Because of the complexity of natural family planning methods, some patients should consider alternative forms of family planning. For example, women who cannot reliably identify their ovulation based on menstrual cycle or cervical mucus may not be candidates for natural family planning. These exclusions include women with irregular periods, such as in polycystic ovarian syndrome or in younger girls whose hypothalamic-pituitary-ovarian axis is not yet mature, such as women who are perimenopausal or postpartum and breastfeeding. These patients may also have irregular periods or mucous and may not be ideal candidates for natural family planning.

Additional non-ideal candidates for natural family planning are women with abnormal uterine bleeding (polyps, fibroids, adenomyosis, hyperplasia or malignancy, etc.) or abnormal cervical bleeding (cervical infections, cervical cancer, etc.). A patient who has undiagnosed abnormal bleeding who presents for family planning counseling should undergo evaluation for that bleeding, and she can employ other options besides natural family planning until her evaluation is satisfactory. Women with cervical or vaginal infections may also have difficulty assessing their cervical mucus. Women who have other reasons for temperature fluctuations, such as systemic illness leading to fever, will not be able to track ovulation based on basal body temperatures accurately.

Some patients or couples may not be able to afford fertility tracking devices. The cost or time off work required to attend classes or instructional sessions may be prohibitive to some. Some individuals may find the tasks of monitoring temperatures or secretions to be onerous or off-putting. Lastly, some couples may find it difficult, or undesirous, to adhere to avoidance of unprotected intercourse during fertile times. The success of natural family planning requires highly motivated patients and couples.

Clinical Significance

Many patients may choose natural family planning. For some patients, religion may play a part in the decision to utilize natural family planning.[13] Regarding contraception, some women may have concerns regarding the potential side effects or complications of other contraceptive methods. Some may have already experienced side effects or complications and are desirous to try what they perceive as more natural methods. Regarding achieving pregnancy, both fertile and infertile couples can benefit from a knowledge of the menstrual cycle and how the hormonal changes affect their bodies. In general, a person armed with the knowledge of their fertility can have more agency over her body and life choices/options than person ignorant of these concepts.

Lack of awareness and education may impact the utilization of natural family planning. In one survey of physicians in the United States, a third did not even mention natural family planning to patients and 40% only discussed natural family planning with select women.[14] Facilitation of autonomy requires physicians to equip patients with adequate knowledge with which to make decisions. Without a comprehensive discussion of options, true informed consent is not possible.

Nursing, Allied Health, and Interprofessional Team Interventions

Because natural family planning often requires time-intensive patient education or multiple instructional sessions, successful use of these methods may benefit from a coordinated team approach. The pharmacist dispensing contraceptive pills or a physician performing a routine wellness visit may identify patients who are interested in pursuing natural family planning. Subsequently, a trained educator (physician, nurse practitioner, etc.) may be called upon to perform the detailed teaching. The awareness of all family planning methods, including natural family planning, will allow physicians and advanced practitioners to provide options that are patient-centered and individualized.

Nursing, Allied Health, and Interprofessional Team Monitoring

Nurse monitoring is two-fold. First, one should monitor for patients who may be motivated to pursue natural family planning or who may be good candidates for natural family planning and facilitate the education of those patients. Patients may confide in the nurse any current or prior discontent with a contraceptive method. The nurse may be the one who elicits that patient’s history of relevant religious background.

Secondly, nurses, especially in the outpatient setting, should monitor for signs that patients may not be candidates for natural family planning. Taking a good menstrual history may identify patients with irregular periods or abnormal uterine bleeding. Monitoring for patients who are unable to give an accurate description of the length or frequency of their periods is crucial, as these patients may be poor candidates for natural family planning. Because these methods require motivation on the part of both members of a couple, it is essential to monitor not only the patient but her partner if possible. The patient may herself be highly interested, but the partner may show signs of hesitance or concern.

Review Questions


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Trussell J. Contraceptive failure in the United States. Contraception. 2011 May;83(5):397-404. [PMC free article: PMC3638209] [PubMed: 21477680]
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Arévalo M, Jennings V, Nikula M, Sinai I. Efficacy of the new TwoDay Method of family planning. Fertil Steril. 2004 Oct;82(4):885-92. [PubMed: 15482764]
Guida M, Tommaselli GA, Pellicano M, Palomba S, Nappi C. An overview on the effectiveness of natural family planning. Gynecol Endocrinol. 1997 Jun;11(3):203-19. [PubMed: 9209901]
Frank-Herrmann P, Heil J, Gnoth C, Toledo E, Baur S, Pyper C, Jenetzky E, Strowitzki T, Freundl G. 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. Hum Reprod. 2007 May;22(5):1310-9. [PubMed: 17314078]
Van der Wijden C, Manion C. Lactational amenorrhoea method for family planning. Cochrane Database Syst Rev. 2015 Oct 12;2015(10):CD001329. [PMC free article: PMC6823189] [PubMed: 26457821]
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Disclosure: Sharon Sung declares no relevant financial relationships with ineligible companies.

Disclosure: Aaron Abramovitz declares no relevant financial relationships with ineligible companies.

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Bookshelf ID: NBK546661PMID: 31536267


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