This paper evaluates a Singapore experiment to test the Shettles ‘rhythm and douche’ method of sex control. The clinic was set up in the hope that if couples could have the son they desired, they would keep their families small in accordance with the goverment's strong commitment to population control. From March 1975 to July 1977, 10,000 newly-wed women were invited to attend the clinic. A thousand women, not all newlyweds, attended at least once. Of the 31 women who had definite sex preferences, who attempted to follow the method, and who gave birth between March 1975 and November 1977, all wanted boys. By chance alone, one would expect about sixteen to have boys. In fact, fourteen had boys. Only six of the 31 women reported using the method completely correctly.

Women attending the clinic at least once were more likely to have an outside job, to have a husband with a professional or managerial job, and to be of Chinese origin compared with the Singapore population. Clients coming either had fertility problems and had no sex preferences or wanted a boy. Of those coming at least once, 70% had no previous children; the rest had had 403 girls and 58 boys.

To test this sex control technique adequately, one would need a large sample of highly committed couples who are given intensive counselling and follow-up. This particular method appears to be impractical on a mass basis, apart from questions about its effectiveness. Other sex control methods currently under research may prove more practical and effective. A better solution would be to discourage boy preference and improve the opportunities for girls.