BACKGROUND AND OBJECTIVES Iron is critical for women's reproduction, and iron-deficiency anemia is a global health problem for mothers. While public health programs have aimed to correct iron deficiency in reproductive-aged women with supplementation, a small group of studies have shown that too much iron also has negative effects on birth outcomes. We hypothesize that women's iron levels evolved within a narrow optimum, and predict that hemoglobin (Hb) levels would be associated with women's fecundity. METHODOLOGY We used the publicly available, longitudinal Tsimane' Amazonian Panel Study to test the association between -Hb levels and hazard of having a next birth (a measure of fecundity) among 116 parous, reproductive-aged Tsimane' women of Bolivia. A Cox proportional hazards model was used to model Hb level and other predictors against the event of next birth across the observation period, which began at each woman's previous birth. RESULTS The higher the Hb level, the lower the hazard of a woman giving birth within the study observation period (hazard ratio=0.82, P = 0.03). However, there was no evidence that low Hb reduced women's fecundity. CONCLUSIONS AND IMPLICATIONS These results demonstrate that high Hb influences women's fecundity. These results supports the growing body of literature showing that iron metabolism is critical for understanding the evolution of women's reproduction. More work is needed to determine the evolved optimal range of iron levels for reproductive-aged women. LAY SUMMARY Lower chance of pregnancy among Tsimane' women with high Hb levels, suggesting evolved optimal Hb levels in women.

中文翻译：

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玻利维亚 Tsimane 妇女的铁质和生育能力。

背景和目标 铁对女性的生殖至关重要，缺铁性贫血是一个全球性的母亲健康问题。虽然公共卫生计划旨在通过补充剂来纠正育龄妇女的铁缺乏症，但一小部分研究表明，铁过多也会对出生结果产生负面影响。我们假设女性的铁水平在一个狭窄的最佳范围内演变，并预测血红蛋白 (Hb) 水平与女性的生育能力有关。方法 我们使用公开的纵向 Tsimane 亚马逊小组研究来测试玻利维亚 116 名经产、育龄 Tsimane 妇女的 -Hb 水平与下一次生育风险（生育能力的衡量标准）之间的关联。Cox 比例风险模型用于模拟 Hb 水平和其他预测因素，以对抗观察期内的下一次出生事件，该观察期从每个妇女的上一次出生开始。结果 Hb 水平越高，女性在研究观察期内分娩的风险越低（风险比=0.82，P = 0.03）。然而，没有证据表明低 Hb 会降低女性的生育能力。结论和启示 这些结果表明高血红蛋白会影响女性的生育能力。这些结果支持越来越多的文献表明铁代谢对于理解女性生殖的进化至关重要。需要做更多的工作来确定育龄妇女铁水平的进化最佳范围。LAY Summary 在 Tsimane 的高 Hb 水平的女性中怀孕的机会较低，