Gray R H, Simpson J L, Bitto A C, Queenan J T, Li C, Kambic R T, Perez A, Mena P, Barbato M, Stevenson W, Jennings V
Department of Population Dynamics, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, MD 21205, USA.
Hum Reprod. 1998 May;13(5):1397-400. doi: 10.1093/humrep/13.5.1397.
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.
这是一项针对采用自然计划生育的女性怀孕情况的多中心前瞻性研究。这些女性记录了受孕周期的自然计划生育图表，记录性交行为和排卵迹象（宫颈黏液变化，包括高峰日和基础体温）。图表用于评估相对于排卵日的最可能授精日以及周期卵泡期的长度。947例单胎分娩的性别比（每100名女性对应的男性数）为101.5，与预期值105无显著差异。性别比并未随着相对于排卵日的估计授精时间、卵泡期的估计长度或怀孕的计划内或计划外状态而持续或显著变化。尽管这些发现可能受到数据不精确性的影响，但该研究表明，在周期内操纵授精时间无法用于影响后代性别。
