• Higher Hemoglobin Lower Fertility

    From ironjustice@21:1/5 to All on Fri Sep 13 19:22:20 2019
    Iron and fecundity among Tsimane' women of Bolivia.
    Miller EM1, Khalil M1.
    Evol Med Public Health. 2019 Jul 4;2019(1):111-120. doi: 10.1093/emph/eoz020. eCollection 2019.

    Author information
    Department of Anthropology, University of South Florida, 4202 East Fowler Ave, SOC107, Tampa, FL, USA.

    Abstract
    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.

    KEYWORDS:
    hemoglobin; iron-deficiency anemia; life history theory; maternal health; reproductive ecology

    PMID: 31402978 PMCID: PMC6682707 DOI: 10.1093/emph/eoz020

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