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Updated: Aug 15, 2026

FISH for Pre-implantation Genetic Diagnosis
Published on: February 23, 2011
Natural family planning and sex selection: fact or fiction?
1Department of Population Dynamics, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205.
Abstract:
Determining sex of offspring by timing of intercourse has been a subject of intense interest for the lay public and professional community. This metaaanalysis of couples practicing natural family planning provides an opportunity to evaluate sex ratios in relation to the timing of conception with several parameters, including basal body temperature shift and peak mucus as markers of ovulation. Data from six studies show a statistically significant lower proportion of male births among conceptions that occur during the most fertile time of the cycle.
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