Pregnancies ending before 26 weeks contribute 1% of births but 40% of infant deaths in the United States. The rate of these “periviable” births to non-Hispanic (NH) Black women exceeds four times that for NH whites. Small male periviable infants remain most likely to die. NH white periviable males weigh more than their NH Black counterparts. We argue that male infants born from twin gestations, in which one fetus died in utero (i.e., the vanishing twin syndrome), contribute to the disparity. We cannot directly test our argument because “vanishing” typically occurs before clinical recognition of pregnancy. We, however, describe and find associations that would emerge in vital statistics were our argument correct. Among male periviable singleton births from 288 monthly conception cohorts (January 1995 through December 2018), we found an average NH white advantage of 30 grams (759 grams versus 729 grams). Consistent with our argument, however, cohorts signaling relatively few survivors of the vanishing twin syndrome showed no disparity.

中文翻译：

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消失的双胞胎、幸免的队列以及美国黑人和白人妇女所生的围产婴儿的出生体重


在美国，26 周前终止妊娠占出生率的 1%，但占婴儿死亡的 40%。非西班牙裔 (NH) 黑人女性的“围产期”生育率是新罕布什尔州白人女性的四倍。体型较小的男性围产儿仍然最有可能死亡。 NH 白人可生育雄性的体重比 NH 黑人同类重。我们认为，双胎妊娠中出生的男婴（其中一个胎儿在子宫内死亡（即双胞胎消失综合症））是造成这种差异的原因之一。我们无法直接检验我们的论点，因为“消失”通常发生在临床承认怀孕之前。然而，如果我们的论点正确，我们会描述并发现生命统计中会出现的关联。在 288 个每月受孕队列（1995 年 1 月至 2018 年 12 月）的男性围产单胎出生中，我们发现 NH 白人的平均体重优势为 30 克（759 克与 729 克）。然而，与我们的论点一致，表明双胞胎消失综合症幸存者相对较少的队列没有表现出差异。