Definition/Introduction

Symptothermal contraception is a birth control method in which women collect information to inform themselves of their menstrual cycle. This method depends on observations during the menstrual cycle of signs and symptoms that correlate with different hormone levels as indicators for an approximate timeframe when ovulation is likely to occur.  Due to the data collection that is required by the patient, symptothermal contraception is commonly referred to as a "fertility-awareness" contraceptive method.[1]

The woman measures her basal body temperature with a thermometer every morning upon awakening. Basal body temperature is defined as the lowest natural body temperature recorded after a period of rest in the absence of pathology. The temperature must be recorded at approximately the same time each day.[2] 

The American College of Obstetricians and Gynecologists (ACOG) states that most women experience an increase in their basal body temperature of 0.5 to 1.0 degree Fahrenheit shortly after ovulation. This increase in temperature is due to an increase in the release of both progesterone and estrogen by the corpus luteum during the luteal phase of the menstrual cycle. This increase in temperature persists until the end of the cycle.[3] The most fertile days are the two to three days before this increase in temperature, during which ovulation most likely occurs.[4] A thermal nadir, the lowest basal body temperature of the cycle, typically occurs the day before ovulation. 

The woman also evaluates their cervical mucus and its texture, consistency, and color every day. During the fertile period of the menstrual cycle, the cervical mucus is reported to be clear, stringy. It can be stretched between two fingers to a length of at least six centimeters long due to an increase in estrogen at the end of the follicular phase before ovulation.[5] This watery consistency is meant to facilitate sperm mobilization for the process of fertilization. This aforementioned change in cervical mucus can be detected approximately four to seven days before ovulation.[3]

To reliably predict the upcoming menstrual cycles, it has been suggested that data collection should be done for approximately six to twelve cycles.[5] Using all of this information, the woman may then chart their menstrual cycle and determine which days they are in the luteal phase, the follicular phase, and which day ovulation is most likely to occur. The woman may then be able to determine their “fertile window,” which is the period of days around ovulation and when conception is most likely to occur.[6] 

Theoretically, the woman may prevent conception by avoiding sexual intercourse during this time period.[7] Women are recommended to abstain from sexual intercourse two to three days prior to the expected increase in their body temperature and up to three days after its initial increase. 

Issues of Concern

The effectiveness rate of using the symptothermal method as a means of preventing unplanned pregnancy is controversial and highly debated. Multiple sources and studies report different results. An observational longitudinal cohort study conducted in Germany since 1985 reported a pregnancy rate of 0.6 per 100 subjects after recording thirteen cycles among 900 subjects. Each of these subjects denied sexual intercourse during their fertile period[8]. Data collected from patients who did not strictly adhere to abstinence from intercourse during their fertile period was eliminated from the study.

Results from another study across five nations by the World Health Organization (WHO) that was published in 1981 reported a method-related pregnancy rate of 2.8 percent. However, the overall pregnancy rate of patients using the method was 22.6 percent[3]. About 19.6 percent of the patients' pregnancies were due to user-related errors during the implementation of the method. 

The main risk associated with this contraceptive method is the failure to prevent conception due to errors in instruction, the method's application, failure to abstain during the fertile period, and unreliable data collection[9]. The primary reason for this method's failure in preventing conception is the inappropriate implementation or lack of patient education. The presence of pathology causing an increase in body temperature, a fever is also an issue of concern relative to data collection. Women who experience inconsistent menstrual cycles may also have difficulty using this method of contraception. 

Due to these variables and the inconsistent data of its effectiveness, symptothermal contraception is not a first-line birth control method. 

Clinical Significance

The number of patients using symptothermal contraception as their primary birth control method has steadily increased an average of 3 to 4 percent since the 1970s.[10] The wide availability of smartphone apps that help women track data related to their menstrual cycle has contributed to its growing popularity.[11] Certain religious groups also strongly encourage their patrons to implement this method as a primary means of contraception.[12] 

Appropriate patient education is absolutely critical for the method to be successful. Therefore, clinicians need to be very knowledgeable and skilled in counseling women about this method as a method of natural family planning. Considering the cost, emotional strain, and potential complications of infertility treatment, clinicians should consider initially recommending a fertility awareness-based method to women seeking advice about achieving pregnancy.[13]

Nursing, Allied Health, and Interprofessional Team Interventions

An interprofessional team that provides a holistic and integrated approach to family planning and contraceptive care can help achieve the best possible outcomes. If the patient wants to develop a plan regarding their fertility and their desires to achieve or prevent a pregnancy, consultation should be made with physicians and community nurses who can monitor the patient and make referrals as needed. An interprofessional team can address some complications in relation to the patient's ability to access birth control and primary health care to optimize the patient's fertility plan. If the patient gets pregnant, the importance of community nurses and obstetric care providers working together as a team to provide care, monitor the patient and ensure a healthy pregnancy cannot be understated. Social workers are imperative in ensuring that the patient has adequate support to care for the baby during pregnancy and after birth.  

Collaboration, shared decision making, and communication are all key elements to achieve the best possible outcome. The best standard care that follows an integrated care pathway combined with an evidence-based approach to planning and evaluation should aim at a women-centered approach. Women should be provided with written information leaflets about the various available contraception methods, and the interprofessional team must ensure that women and their families are fully supported during their decision making process about the best method that suits them. The preferences, beliefs, and values of women and their families should be respected at all times. [Level 5]