Sex ratio associated with timing of insemination and length of the follicular phase in planned and unplanned pregnancies during use of natural family planning

Ronald H. Gray, Joe L. Simpson, Adenike C. Bitto, John T. Queenan, Chuanjun Li, Robert T. Kambic, Alfredo Ferez, Patricio Mena, Michele Barbato, Wilma Stevenson, Victoria Jennings

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

This was a multicentred, prospective study of pregnancies among women using natural family planning. The women maintained natural family planning charts of the conception cycle, recording acts of intercourse and signs of ovulation (cervical mucus changes, including peak day and basal body temperature). Charts were used to assess the most probable day of insemination relative to the day of ovulation and length of the follicular phase of the cycle. The sex ratio (males per 100 females) for 947 singleton births was 101.5, not significantly different from the expected value of 105. The sex ratio did not vary consistently or significantly with the estimated timing of insemination relative to the day of ovulation, with the estimated length of the follicular phase or with the planned or unplanned status of the pregnancy. Although these findings may be affected by imprecision of the data, the study suggests that manipulation of the timing of insemination during the cycle cannot be used to affect the sex of offspring.

Original languageEnglish (US)
Pages (from-to)1397-1400
Number of pages4
JournalHuman Reproduction
Volume13
Issue number5
DOIs
StatePublished - 1998

Keywords

  • Follicular phase length
  • Natural family planning
  • Planned and unplanned pregnancies
  • Sex ratio
  • Timing of conception

ASJC Scopus subject areas

  • Reproductive Medicine
  • Obstetrics and Gynecology

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