Could the contraceptive pill be replaced by a “natural” approach to family planning? It could if a study by Petra Frank-Herrmann of the Department of Gynaecological Endocrinology at the University of Heidelberg, Germany, proves reproducible (pardon the pun).
She and her colleagues have demonstrated that using two indicators for the fertile period in a woman’s menstrual cycle and avoiding unprotected sex during that time is just as effective as the contraceptive pill for avoiding unplanned pregnancies. The study was published in Human Reproduction this week.
The symptothermal method (STM) uses temperature and cervical secretion to pinpoint a woman’s fertile time. The German team carried out the largest prospective study of the method yet and found that if couples abstained from unprotected sex during this time the rate of unplanned pregnancies per year was 0.4% and 0.6% respectively. Out of all the 900 women who took part in the study, including those who had unprotected sex during their fertile period, 1.8 per 100 became unintentionally pregnant.
“For a contraceptive method to be rated as highly efficient as the hormonal pill, there should be less than one pregnancy per 100 women per year when the method is used correctly,” Frank-Herrman explains, “The pregnancy rate for women who used the STM method correctly in our study was 0.4%, which can be interpreted as one pregnancy occurring per 250 women per year.”
The authors were also surprised by the relatively low rate of unintended pregnancies (7.5%) among women who had unprotected sex during their fertile period. “If people are trying for pregnancy you expect a pregnancy rate of 28% per cycle,” said Frank-Herrmann. “Therefore, we think that some of the couples were practicing conscious, intelligent risk-taking, and were having no unprotected sex during the few highly fertile days, but had unprotected intercourse on the days at the margins of the fertile time when the risk of pregnancy was lower.”