1 Department of Endocrinology & Nutrition, Hospital de la Santa Creu i Sant Pau , Barcelona, Spain .
Thyroid. 2013 Dec;23(12):1514-7. doi: 10.1089/thy.2012.0530. Epub 2013 Sep 3.
The sex ratio at birth (male out of total alive newborns) is historically established at 0.515 and is influenced by numerous factors. It is not known, however, whether it is influenced by maternal thyroid conditions. Our aim was to analyze its association with maternal thyroid autoimmunity and first-trimester thyrotropin (TSH).
We performed a retrospective cohort study at a tertiary care center. We studied 167 women who had received pregestational treatment with levothyroxine for hypothyroidism or differentiated thyroid carcinoma and gave birth to live infants. Women with secondary/tertiary hypothyroidism, pregestational diabetes mellitus, or multiple pregnancies were excluded. Autoimmunity was defined as present/absent, and mean first-trimester TSH was tested both as a quantitative variable and using six predefined categories. The outcome measure was sex ratio at birth.
The sex ratio at birth was 0.485, not significantly different from expected. Maternal characteristics were similar in mothers of female and male newborns with the exception of mean first-trimester TSH, which was higher in pregnancies of female fetuses (3.27 vs. 2.52 mUI/L, p<0.025). Newborn sex differed across predefined TSH categories (p<0.021, with a sex ratio of 0.200 [95% confidence interval 0.00-0.402] for TSH ≥10 mUI/L). A multiple logistic regression analysis to predict newborn male sex confirmed maternal mean first-trimester TSH as the single predictor (odds ratio 0.900 [95% confidence interval 0.823-0.984], p<0.020).
In women under pregestational treatment with levothyroxine, mean maternal first-trimester TSH is negatively associated with sex ratio at birth. This association has not been previously described.
出生性别比（男性新生儿总数）历史上设定为 0.515，并受众多因素影响。然而，目前尚不清楚它是否受产妇甲状腺状况的影响。我们的目的是分析其与产妇甲状腺自身免疫和孕早期促甲状腺激素（TSH）的关系。
我们在一家三级保健中心进行了一项回顾性队列研究。我们研究了 167 名患有甲状腺功能减退症或分化型甲状腺癌并接受孕前左旋甲状腺素治疗的女性，她们生育了活产婴儿。排除患有继发性/三发性甲状腺功能减退症、孕前糖尿病或多胎妊娠的女性。自身免疫定义为存在/不存在，并分别作为定量变量和使用六个预设类别检测孕早期 TSH 均值。出生性别比为结局指标。
出生性别比为 0.485，与预期值无显著差异。除了孕早期 TSH 均值，母亲特征在女婴和男婴的母亲中相似，女胎的 TSH 均值更高（3.27 与 2.52 mIU/L，p<0.025）。新生儿性别在不同的 TSH 预设类别中存在差异（p<0.021，TSH≥10 mIU/L 的类别中，性别比为 0.200[95%置信区间 0.00-0.402]）。为预测男婴出生，我们进行了多因素逻辑回归分析，证实了母亲孕早期 TSH 均值是唯一的预测指标（优势比 0.900[95%置信区间 0.823-0.984]，p<0.020）。
在接受孕前左旋甲状腺素治疗的女性中，母亲孕早期 TSH 均值与出生性别比呈负相关。这种关联以前尚未描述过。
