The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)


Evolutionary ecology of nausea and vomiting of pregnancy in Yasawa Island, Fiji

LUSEADRA J. MCKERRACHER1, MARK COLLARD1 and JOSEPH HENRICH3.

1HESP and Archaeology, Simon Fraser University, 2HESP and Archaeology, Simon Fraser University, 3Psychology and Economics, University of British Columbia

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Nausea and vomiting of pregnancy (NVP) refers to a suite of traits, including nausea, vomiting, and novel food aversions, that many women experience during early pregnancy. Given that many of these traits impose energetic costs, the existence of NVP is puzzling from an evolutionary perspective.

Three main hypotheses have been advanced to explain NVP. The byproduct hypothesis suggests that embryos prevent mothers from aborting them by disrupting maternal endocrinology and this disruption incidentally causes NVP. The compensatory placental growth hypothesis holds that embryos cause NVP to reduce maternal calorie consumption because mothers invest more energy in pregnancies when mildly calorie restricted during placentation. The maternal-embryo protection hypothesis contends that NVP minimizes embryo exposure to pathogens and chemical toxins during a crucial phase of embryo development.

We tested these hypotheses with dietary and NVP data obtained from interviews with 70 women from Yasawa Island, Fiji. The hypotheses offer different predictions regarding the foods likely to become aversive during early pregnancy. The byproduct hypothesis predicts that aversions should focus on foods encountered by mothers most frequently. The compensatory placental growth hypothesis predicts that aversions should focus on macronutrient-dense foods. The maternal-embryo protection hypothesis predicts that relatively high pathogen and toxin loads should be foci for aversions.

We found that, in Yasawan women, novel aversions focus on animal foods and on toxic plants. Thus, our findings are most consistent with the maternal-embryo protection hypothesis, as the foods most aversive during early pregnancy are those most likely to disrupt embryo development and maternal health.

LM: SSHRC-CGS-727-2011-3333, 2011-2014 JH: Canada Research Chairs Program, SSHRC, UBC MC: Canada Research Chairs Program, CFI, BCKDF, SFU

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