The TwoDay Method is a Fertility awareness method used to either avoid or achieve pregnancy.
Background
The TwoDay method is a simple fertility awareness method requiring users to check for cervical secretions twice a day. If secretions were not observed for two consecutive days, pregnancy is unlikely on the second. At other times, pregnancy is considered more likely.2
With perfect usage, 3.5 out of 100 people will get pregnant in the first year of use and, under typical use, 13.7 out of 100 people will get pregnant in the first year.3
Limitations
Similar to other fertility awareness methods, the TwoDay Method requires women to abstain from vaginal sex or use a barrier method on days identified as fertile.4
References
Sinai, Irit; Jennings, Victoria; Arévalo, Marcos (1999-08-01). "The twoday algorithm: a new algorithm to identify the fertile time of the menstrual cycle". Contraception. 60 (2): 65–70. doi:10.1016/S0010-7824(99)00072-4. ISSN 0010-7824. PMID 10592852. https://www.sciencedirect.com/science/article/pii/S0010782499000724 ↩
Sinai, Irit; Jennings, Victoria; Arévalo, Marcos (1999-08-01). "The twoday algorithm: a new algorithm to identify the fertile time of the menstrual cycle". Contraception. 60 (2): 65–70. doi:10.1016/S0010-7824(99)00072-4. ISSN 0010-7824. PMID 10592852. https://www.sciencedirect.com/science/article/pii/S0010782499000724 ↩
Arévalo, Marcos; Jennings, Victoria; Nikula, Minna; Sinai, Irit (2004-10-01). "Efficacy of the new TwoDay Method of family planning". Fertility and Sterility. 82 (4): 885–892. doi:10.1016/j.fertnstert.2004.03.040. ISSN 0015-0282. PMID 15482764. https://www.sciencedirect.com/science/article/pii/S0015028204012518 ↩
"Fertility Awareness-Based Methods of Family Planning". www.acog.org. Retrieved 2024-07-20. https://www.acog.org/womens-health/faqs/fertility-awareness-based-methods-of-family-planning ↩