Frequency of Sexual Intercourse Does Not Determine Baby's Sex
No, the frequency of sexual intercourse does not influence whether you conceive a boy or girl. The highest quality prospective study directly addressing this question found no relationship between coital frequency and offspring sex 1.
Evidence Against Frequency Affecting Sex Ratio
The most rigorous evidence comes from a prospective study of 221 women planning pregnancy, which tracked 625 menstrual cycles and 192 conceptions using objective urinary hormone measurements to precisely time ovulation 1. This study definitively showed that cycles producing male and female babies had similar patterns of intercourse in relation to ovulation, with no influence of intercourse frequency or timing on sex determination 1.
What Actually Matters: Biological Sex Determination
Sex is determined at conception by which sperm (X or Y chromosome) fertilizes the egg—this is a random biological event unaffected by behavioral factors like coital frequency 1.
The primary sex ratio (proportion of males at conception) remains approximately 1:1 across populations due to evolutionary principles of equal parental investment in both sexes 2.
Timing Theories Are Also Unsupported
While some older theories suggested timing intercourse relative to ovulation might influence sex ratio, the best evidence refutes this:
The 1995 New England Journal of Medicine study found no relationship between the timing of intercourse relative to ovulation and offspring sex 1.
Earlier studies showed conflicting results, with one suggesting longer intervals between coitus and ovulation favored males 3, while another suggested the opposite 4. These inconsistencies reflect methodological limitations rather than true biological effects.
Clinical Bottom Line
Couples cannot reliably influence their baby's sex through any pattern of sexual intercourse—neither frequency, timing, nor any other behavioral modification 1.
The only clinically relevant methods for sex selection involve laboratory sperm separation techniques (albumin or Sephadex column filtration), which have reported 70-80% success rates but remain controversial and are primarily used to avoid sex-linked genetic disorders 4.
Natural conception results in approximately equal numbers of male and female offspring regardless of sexual behavior patterns 1, 2.