17th December 2012 12:39
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[quote:2evf1051]The IVF pioneer Landrum B Shettles (1970) called attention to the timing method, which has resulted in a rich literature on the topic (e.g. McSweeney, 1993, Wilcox et al., 1995). Unfortunately, many results are contradictory, mainly because most studies are beset by the same major problem: a low level of accuracy and reliability of estimating the time of ovulation. Multiple inseminations were not always registered and ovulation was determined based on basal body temperature only, or was even supposed to take place for all women on a fixed day during the menstrual cycle. Nowadays urinary LH-based home tests can be used to determine ovulation very accurately (Grenache and Gronowski, 2003). Many consider the article by Wilcox et al. (1995) to be the definite evidence against the timing method and the conclusion by this study, ‘For practical purposes, the timing of sexual intercourse in relation to ovulation has no influence on the sex of the baby’, has been quoted many times. However, closer scrutiny of their data shows that there are a mere five cases for which coitus was certain to have taken place inside the female window of 3–4days before ovulation, out of a total of 129, so the quantitative basis for their conclusion is not very impressive. [b:2evf1051]Data on artificial insemination performed around the ovulation shows a preponderance of male babies (Mortimer and Richardson, 1982, Sampson et al., 1983), which implicitly supports the timing theory. Of a total of 12,346 babies conceived using fresh semen, only 42.3% were female (P=0).[/b:2evf1051][/quote:2evf1051]
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