Women who monitor their fertility signs and recognize when they are fertile
can use this knowledge to conceive or to avoid pregnancy. Studies have sho
wn that there is a rather small fertile window of several days during each
menstrual cycle. Established methods of identifying the fertile window, suc
h as the Ovulation and the Symptothermal methods of Natural Family planning
can be very effective in helping couples avoid pregnancy. A new algorithm
for identifying the fertile window has been developed, based on monitoring
and recording of cervical secretions. The TwoDay Algorithm appears to be si
mpler to teach, learn, and use than current natural methods. A large existi
ng data set from a World Health Organization study of the Ovulation Method,
along with Natural Family Planning charts from women using the Ovulation M
ethod and the Symptothermal Method, were used to determine the potential ef
fectiveness of the TwoDay Algorithm in identifying the fertile window. Resu
lts suggest that the algorithm can be an effective alternative for low lite
racy populations or for programs that find current Natural Family Planning
methods too time consuming or otherwise not feasible to incorporate into th
eir services. Further studies are needed to determine the efficacy of the T
woDay Algorithm in avoiding pregnancy and to assess its acceptability to us
ers and providers. CONTRACEPTION 1999;60: 65-70 (C) 1999 Elsevier Science I
nc. All rights reserved.