Taylor Kira C, Jackson Leila W, Lynch Courtney D, Kostyniak Paul J, Buck Louis Germaine M
Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Development (NICHD), NIH, DHHS, 6100 Executive Blvd, Room 7B03, Rockville, MD 20852, USA.
Environ Res. 2007 Jan;103(1):99-105. doi: 10.1016/j.envres.2006.04.009. Epub 2006 Jun 14.
The secondary sex ratio is the ratio of male to female live births and historically has ranged from 102 to 106 males to 100 females. Temporal declines have been reported in many countries prompting authors to hypothesize an environmental etiology. Blood specimens were obtained from 99 women aged 24-34 prior to attempting pregnancy and quantified for 76 polychlorinated biphenyl (PCB) congeners using dual column gas chromatography with electron capture detection. Women were prospectively followed until pregnancy or 12 cycles of trying. The odds of a male birth for three PCB groupings (total, estrogenic, anti-estrogenic) controlling for maternal characteristics were estimated using logistic regression. Among the 50 women with live births and PCB data, 26 female and 24 male infants were born (ratio 0.92). After adjusting for age and body mass index, odds of a male birth were elevated among women in the second (OR=1.29) and third (OR=1.48) tertiles of estrogenic PCBs; odds (OR=0.70) were reduced among women in the highest tertile of anti-estrogenic PCBs. All confidence intervals included one. The direction of the odds ratios in this preliminary study varied by PCB groupings, supporting the need to study specific PCB patterns when assessing environmental influences on the secondary sex ratio.
出生性别比是指男女性活产儿的比例，历史上该比例为每100名女婴对应102至106名男婴。许多国家都报告了该比例随时间下降的情况，促使作者推测其环境病因。在99名年龄在24至34岁、准备怀孕的女性尝试怀孕前采集血液样本，使用带电子捕获检测的双柱气相色谱法对76种多氯联苯（PCB）同系物进行定量分析。对这些女性进行前瞻性跟踪，直至怀孕或尝试12个周期。使用逻辑回归分析，在控制产妇特征的情况下，估计了三个PCB分组（总PCB、雌激素类PCB、抗雌激素类PCB）生出男婴的几率。在50名有活产儿且有PCB数据的女性中，出生了26名女婴和24名男婴（比例为0.92）。在调整年龄和体重指数后，雌激素类PCB第二三分位数（OR = 1.29）和第三三分位数（OR = 1.48）的女性生出男婴的几率升高；抗雌激素类PCB最高三分位数的女性生出男婴的几率降低（OR = 0.70）。所有置信区间均包含1。这项初步研究中几率比的方向因PCB分组而异，这支持了在评估环境对出生性别比的影响时研究特定PCB模式的必要性。
