Natural fertility methods have a bad rep, mainly due to being grossly misunderstood. One of the reasons is that many other methods out there don't promote the most effective natural fertility or Fertility Awareness Based Method (FABM). An effective FABM is one that relies on more than one biomarker, such as the Symptothermal method, which includes temperature and cervical mucus. Dr. Joshua U. Klein, Assistant Clinical Professor of OB/GYN – Mt. Sinai School of Medicine, and Medical Director at Reproductive Medicine Associates of New York — Brooklyn Office, explains the Symptothermal Method.
Natural fertility management is based on the science of the Symptothermal Method (STM) which uses natural biomarkers – temperature measurement and cervical mucus assessment – to identify the fertile time of the menstrual cycle. By combining these factors, a woman can confidently detect when her fertile time begins and ends, as well as confirm that ovulation has occurred in a healthy way. Whether a woman is struggling with her fertility or just starting to plan a pregnancy, many scientific studies have validated the science of STM, and how STM can help a woman get pregnant safely and efficiently.
Groundbreaking studies led by the NIH and published in the New England Journal of Medicine and other leading journals proved the existence of a “Fertile Window”: there are six days surrounding the time of ovulation during which it is possible to conceive. Achieving pregnancy outside of the Fertile Window has never been documented and is biologically implausible (1, 2).
By tracking cervical mucus and basal body temperature, a woman can effectively identify the “opening” of the fertile window and the presence and timing of ovulation. In one study, as compared with using expensive and invasive vaginal ultrasound and hormone measurements, women using STM were able to accurately and precisely identify the timing of ovulation to within 1 day in 89% of cases (3).
Timing intercourse to the Fertile Window can increase the chances a woman might conceive in a given period of time; in one study, the number of women who got pregnant over 2 months by timing intercourse was almost double the number of women who were not timing intercourse (4). Women who track their fertility increase their chances of getting pregnant sooner once they decide to try and conceive (5, 6).
Measuring urinary hormones (LH and estrogen metabolites) is another effective way to identify the fertile window. However, in addition to cost considerations, STM provides several additional levels of information compared to urine testing alone.
Confirmation of ovulation: urine kits can predict ovulation but will not confirm it actually occurs. In one study, doing an endometrial biopsy to more definitively confirm ovulation revealed that the kit was a “false positive” more than 7% of the time (i.e. almost once a year in an average woman) (7). By incorporating temperature readings, STM can provide evidence that ovulation actually has occurred.
Facilitating pregnancy: The quantity and character of cervical mucus changes during the course of the menstrual cycle. Fertile cervical mucus plays an important role in allowing sperm to find and fertilize the egg after ovulation. Several research studies have demonstrated that cervical mucus status can predict the chance of conception as well as, or even better than, timing intercourse by other markers of ovulation such as urine testing (8, 9). In one study, the chance of conception on a day with the most fertile cervical mucus (29%) was almost 100 times greater than the chance on a day with the least fertile cervical fluid (0.3%; 10).
Even if a woman does not get pregnant by tracking her cycles, the information generated by using STM will help a woman effectively navigate the path the pregnancy. STM can reveal absent, irregular, or even dysfunctional ovulation; the presence of any of these conditions will help guide an OB/GYN or fertility specialist in decisions regarding the timing and aggressiveness of workup and treatment. For example, although those younger than 35 are usually advised to try for at least one year before consulting with a physician regarding infertility, if STM demonstrates an abnormality in ovulation, a fertility specialist would typically recommend initiating a workup and treatment without any delay (11).
STM can help women conveniently and confidently identify their Fertile Window, time intercourse appropriately, and ultimately increase the chances of getting pregnant in a shorter period of time. Tracking cycles using STM can reveal important issues with a woman’s reproductive health that may be important in helping achieve pregnancy, even if she needs the care of an OB/GYN or fertility specialist to help her conceive. For many, charting/STM is the best first step toward getting pregnant in an efficient, organized, and intelligent way.
Joshua U. Klein, MD
Division of Reproductive Endocrinology and Infertility
Department of Obstetrics and Gynecology
Columbia University Medical Center
1. Wilcox et al. New England Journal of Medicine 1995; 333:1571-1521.
2. Dunson et al. Human Reproduction 1999; 14:1835-1839.
3. Frank-Herrmann et al. Gynecological Endocrinology 2005; 20:305-312.
4. Robinson et al. Fertility and Sterility 2007; 87: 329-334.
5. Stanford et al. Obstetrics and Gynecology 2002; 100;1333-1341.
6. Gnoth et al. Human Reproduction 2003; 1959-1966.
7. McGovern et al. Fertility and Sterility 2004; 82:1273-1277.
8. Stanford et al. Obstetrics and Gynecology 2003; 101:1285-1293.
9. Bigelow et al. Human Reproduction 2004; 19:889-892.
10. Scarpa et al. European Journal of Obstetrics, Gynecology, & Reproductive Biology 2006; 125:72-78.
11. Practice Committee of the American Society for Reproductive Medicine. Fertility and Sterility 2008; 90:S1-6.