Fertility Awareness-Based Methods for Family Planning: A Systematic Review.

Family planning is crucial for empowering individuals and couples to make informed decisions about their reproductive health and ensure better maternal and child health outcomes. It helps reduce unintended pregnancies, lowers the risk of unsafe abortions, and supports economic stability by allowing families to plan for their future [ 1 ]. Fertility awareness-based methods (FABMs) of family planning comprise tracking numerous indications and symptoms of fertility throughout the menstrual cycle to determine the fertile window, or the days of the cycle when unprotected intercourse is most likely to result in pregnancy [ 2 ]. This contrasts with pharmacological or procedural interventions. FABMs track basal body temperature, cervical mucus changes, urinary hormone levels, or menstrual cycle patterns. These methods serve dual purposes as they can help avoid unintended pregnancies but also can help with conception [ 3 ]. FABM is essentially categorized into four types: (i) Calendar-based methods rely on cycle length and day counting, (ii) cervical mucus-based methods rely on observing and tracking vulvar discharge, (iii) symptom-thermal methods (STM) combine cervical mucus and basal body temperature observations, and (iv) symptom-hormonal methods combine mucus observation with technology to detect urinary hormonal metabolites associated with ovulation and fertility [ 4 ]. The utility of FABMs varies with region. For example, in the United States, FABMs are utilized by approximately 3% of contraceptive users [ 5 ]. However, a study conducted in Riyadh reported that 8.6% of women used the rhythm method (calendar method) [ 6 ]. FABMs also offer other advantages as well. They encourage partner involvement, improve communication, and enhance body literacy by tracking female biomarkers to determine fertility status. These methods positively influence relationships and help diagnose ovulation-related disorders, such as PCOS and endometriosis, which commonly affect reproductive health [ 7 ]. The most significant impediments to fertility awareness education in general practices are short consultations, time constraints for general practitioners, and a lack of patient educational resources and payment to support their delivery [ 8 ]. Despite their potential, FABMs are often underutilized and misunderstood in many regions, including both high-income and low-income countries [ 9 ]. In recent years, the prevalence of FABMs has risen, a trend that could be attributed to the rapid rise in population and adoption of digital apps for tracking the menstrual cycle [ 10 ]. Historically, FABMs were used as natural family planning methods where family planning was based on observing signs and symptoms. However, recently, the incorporation of digital technologies has led to the development of various FABM apps to track symptoms and cycles, which were previously done manually. This has led to an increase in the success rate [ 7 ]. Previously, systematic reviews have demonstrated the success of different FABMs in contraception and increasing conception rates [ 7 , 11 ]. However, these systematic reviews did not include the latest evidence on the topic. Therefore, this systematic review was conducted to comprehensively assess the effectiveness and outcomes of FABMs in family planning. The findings will help inform healthcare providers, policymakers, and individuals about the role of FABMs in modern family planning and guide future research in this important area of reproductive health.

Methods This systematic review followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [ 12 ]. Search Strategy To identify relevant studies, PubMed, Web of Science, and CINAHL Ultimate were searched by using keywords related to fertility awareness-based methods for family planning. Furthermore, Google Scholar was also searched to further expand the list of potential studies. The keywords used in the search included ‘‘fertility awareness,’’ ‘‘natural family planning,’’ ‘‘rhythm method,’’ ‘‘cervical mucus method," "family planning," and "contraception". These keywords were combined by using AND and OR operators. Details of complete keyword combination are provided in Table 3 in the Appendices. Study Eligibility The PICOS for the systematic review included population (P): women of reproductive age (18-49 years) who have utilized FABMs, interventions (I): any fertility awareness-based method for family planning, comparators (C): hormonal contraceptives (oral pills, patches, injections), long-acting reversible contraception (IUDs, implants), barrier methods (condoms, diaphragms), sterilization procedures, or no contraception use, outcomes (O): effectiveness, implementation success, and study design (S): randomized controlled trials (RCTs), prospective studies, and retrospective studies. To ensure the inclusion of the latest evidence, the systematic review focused on studies published and conducted between 2014 and 2024, investigating fertility awareness-based methods for family planning. The exclusion criteria included studies that did not investigate the efficacy of fertility awareness-based family planning methods and those that were not published in English language. Study Selection After retrieving results from the database search, the files were uploaded to a screening software, Rayyan [ 13 ]. In the first stage, duplicates were removed before beginning the screening process. Two independent reviewers were involved in the screening process. Both reviewers were blinded to each other’s decisions. During screening, records were first screened based on the title and abstract. After completing the initial screening, the blind was removed in Rayyan, and decisions were compared by other reviewers. In case a shared decision was not achieved, a third reviewer was involved. Finally, a full-length screening was performed. After making the final decision to include studies, the data was extracted from studies including demographic details and success rate. Quality Assessment The quality assessment was performed by two independent reviewers. For retrospective and prospective studies, the Newcastle-Ottawa Scale (NOS) tool was used [ 14 ]. For randomized studies, the Revised Cochrane risk of bias tool for randomized trials (ROB2) was used [ 15 ]. The NOS checklist has eight questions spread across three categories, which examine how well the study cohort represents the general population, whether confounding factors are controlled, and any biases in measuring outcomes. Results Included Studies A total of 4193 studies were found during the initial database search. A total of 1341 studies were identified from PubMed, 2788 from Web of Science, 39 from CINAHL Ultimate, and 25 from Google Scholar. A total of 867 duplicates were removed before the screening process. During initial screening, 2762 studies were excluded based on the title and abstract of the records. Of the 557 studies further screened, only 16 studies met the inclusion criteria. Flow Diagram Figure 1 shows the PRISMA flow diagram of this systematic review. PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses Study Characteristics A total of 20,339 participants were included in the 16 studies. Regarding study design, 11 were prospective, two were retrospective, two were randomized, and one was a longitudinal study. The age of the included participants ranged from 18 to 47 years. Of the included studies, five studies mainly focused on contraception, whereas 11 mainly targeted conception rates. Digital fertility awareness-based method was the most common method used in four studies, whereas a similar number of studies (n=4) used digital tracking method or cervical mucus monitoring (CMM), or both. The Creighton Model FertilityCare System was used in two studies. App-connected ovulation test system, hormonal contraception (HC) vs. contraceptive mobile application, natural fertility indicators, Marquette model, CMM, and self-observation with the Sensiplan method were used in one study each. The success rate could only be calculated from 13 studies, which showed an average success rate of 69.5%. However, five of these studies reported success rates exceeding 90%. In some studies, the success rate was not explicitly stated. For example, Stanford et al. [ 16 ] reported that the probability of conception was increased by 20% with their planning method. Table  1  shows the details of the main findings of the included studies. NFP: Nurse-managed natural family planning; EHFM: Electronic hormonal fertility monitor; CMM: Cervical mucus monitoring; TTP: Time to pregnancy Quality Assessment Only two studies used a randomized controlled study design and were assessed with the ROB 2 tool. Only Johnson et al. [ 22 ] reported some concern regarding the randomization process. All other domains including deviation from intended interventions, missing data, outcome assessment, and reported results had low risk (Figure  2 ). Table  2  shows the risk of bias performed for retrospective and prospective studies. Only Favaro et al. [ 21 ] had a moderate risk of bias, whereas all other studies had low risk of bias. Most studies had risk of bias in the representativeness of the exposed cohorts and controls for other risk factors. Stanford et al. [ 25 ] had the highest quality score. Discussion The analysis of data from 20,339 participants from 16 included studies showed that FABMs can achieve significant success rates when used correctly. The use of FABMs was associated with success in more than half of the cases; however, when used correctly, it resulted in a success rate of over 90%. Our findings align with several previous systematic reviews that have evaluated the efficacy of FABMs on family planning [ 7 , 11 ]. For example, Urrutia et al. in their systematic review reported that first-year typical use pregnancy rates varied widely across fertility awareness-based methods, ranging from as low as 1.8 (Sensiplan and Marquette Monitor methods used for contraception) to as high as 33.6 (Billings Ovulation Method used for both conception and contraception) [ 5 ]. Another common factor identified in the present systematic review, with Urrutia et al., was the lack of studies on each method assessing their efficacy. Similarly, Duane et al., in their systematic review, reported that FABMs are effective for family planning, and even physicians can also use them effectively to restore reproductive and endocrine systems [ 7 ]. Other reviews that have evaluated the efficacy of FABMs have also supported their use for family planning. A systematic review by Grimes et al. included only randomized controlled trials in their analysis [ 32 ]. Their findings did not reveal any significant difference among the different FABMs. They also highlighted the paucity of randomized trials, which was also seen in the present systematic review, as only two randomized trials were found. Although randomized trials provide the highest level of evidence, dividing women into different FABMs can be ethically and logistically challenging. Manhart et al., in their review, which included both randomized controlled trials and non-randomized studies, reported that when FABMs were used correctly, they resulted in less than 5% unintended pregnancy rates [ 4 ]. However, their systematic review did not clearly describe the evidence base. Compared to the previous systematic review, the current systematic review provides the latest evidence as the search was limited to the last 10 years only. The current systematic review also identified that in most studies, women used apps or electronic tracking systems to identify more fertile days. This finding is explainable as the use of technology has increased tremendously over the years. Mobile apps can successfully track fertile days by not only tracking menstruation but also physiological parameters using sophisticated mathematical algorithms [ 33 ]. In mobile applications, several parameters, when analyzed together, can lead to higher probability accuracy. For example, in a study by Bull et al., data was analyzed from 612,613 ovulatory cycles, which showed that only 20% of participants had menstrual cycle period of 28 days [ 34 ]. The mean duration was 29.3 days. Furthermore, over time, the cycle length decreased by 0.18 days. Differences based on BMI were also observed, with women with BMI>35 having 0.4 days higher length of menstrual cycle compared to BMI of 18.5-25 [ 34 ]. These intraindividual variations highlight consideration for these factors in FABMs. The success of FABMs also depends on behavioral factors. Mu and Fehring observed that intercourse timed during the high or peak fertility phases resulted in an 87% pregnancy rate at 12 months compared to a mere 5% when intercourse was limited to low-fertility days [ 26 ]. The transition from traditional paper-based or manual methods to digital fertility tracking applications represents a significant paradigm shift in FABMs. Digital tools harness data analytics, machine learning algorithms, and user-friendly interfaces to provide personalized insights into menstrual cycle patterns [ 35 ]. However, traditional methods still hold value, especially in contexts where digital tools may not be accessible or preferred due to cultural or personal reasons. The Creighton Model and Sensiplan, for example, continue to be viable options, particularly when delivered within a structured educational framework [ 25 , 29 ]. The application and success of FABMs also depend on the knowledge level of the health professionals, so they can guide their use. However, the knowledge level of health professionals and medical students varies. For example, a study reported that the calendar technique was the most popular FABM technique among medical students at 84.9% [ 36 ]. Similarly, another study that conducted logistic regression analysis applied to the 2013-17 National Survey of Family Growth (NSFG) showed that 3.4% of contraceptive users (176 respondents) used FABMs. FABM users were considerably different from those who used other contraception methods in terms of relationship status, education, parity, health insurance, and religious affiliation. After adjusting for sociodemographic variables, FABM users had lower odds of ever using the pill, higher odds of giving up on it owing to dissatisfaction, and higher odds of intending to have more children than users of other contraceptive methods [ 10 ]. Another study showed that approximately 18% of contraception users used FABMs [ 37 ]. Strengths and limitations The main strength of this systematic review was that latest evidence was included in the systematic review. Another strength of this systematic review was that systemic search was conducted in various key databases. Furthermore, the systematic review included more than 20,000 participants. Furthermore, both randomized and longitudinal studies were included. The included studies also focused on both contraception and participants trying to conceive. However, there are some limitations as well which should be considered while interpreting the findings. Firstly, most of the studies relied on self-reported data, which could have introduced bias in findings. Another limitation was that studies only included participants who were willing to participate and had higher knowledge levels compared to the general population. This may limit the generalizability of the findings in the general population.

The findings of the present study showed that FABMs are effective in family planning, whether the contraception is targeted or the goal is to conceive. Furthermore, the success rate was associated with correct use. Studies showed that when FABMs were used correctly, they were associated with a more than 90% success rate for both conception and contraception purposes. The success rates also varied based on the different FABMs used. Digital methods, in particular, show promise due to their ability to reduce user error through automated tracking and personalized feedback. However, the effectiveness of these methods is heavily contingent upon user education, adherence, and the accurate interpretation of fertility signals. There are some limitations of the included studies as well, which should be addressed in larger studies with a longer follow-up duration.