Lancet (London, England), 2(7558), 8-10
502 couples used the basal-body-temperature method of regulating births through 8294 cycles. The overall failure-rate in those confining coitus to the postovulatory phase of the menstrual cycle was 6·6 pregnancies per 100 women-years, while in those having coitus in the preovulatory and postovulatory phases it was 19·3 pregnancies per 100 women-years. The biological effectiveness of the method was greater than this, and was achieved by certain subgroups in the survey.
Marshall, J. (1968). A field trial of the basal-body-temperature method of regulating births. *Lancet (London, England)*, *2*(7558), 8-10. https://doi.org/10.1016/s0140-6736(68)92886-9
Marshall J. A field trial of the basal-body-temperature method of regulating births. Lancet. 1968;2(7558):8-10. doi:10.1016/s0140-6736(68)92886-9
Marshall, John. "A field trial of the basal-body-temperature method of regulating births." *Lancet (London, England)*, vol. 2, no. 7558, 1968, pp. 8-10.
Adult, Age Factors, Body Temperature, Contraception, Family Characteristics, Female, Humans, Male, Marriage, Ovulation, Periodicity, Pregnancy, Religion, Social Class