Firstborn sex defines early childhood growth of subsequent siblings |
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| Authors: | Samuel Schfer Felicia Sundling Anthony Liu David Raubenheimer Ralph Nanan |
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| Institution: | 1.Department of Clinical and Experimental Medicine, Linköping University, Linköping 58185, Sweden;2.Charles Perkins Centre—Nepean, Sydney Medical School—Nepean, The University of Sydney, Penrith, New South Wales 2751, Australia;3.Charles Perkins Centre, The University of Sydney, Camperdown, New South Wales 2006, Australia |
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| Abstract: | Animal studies have shown that maternal resource allocation can be sex-biased in order to maximize reproductive success, yet this basic concept has not been investigated in humans. In this study, we explored relationships between maternal factors, offspring sex and prenatal and postnatal weight gain. Sex-specific regression models not only indicated that maternal ethnicity impacted male (n = 2456) and female (n = 1871) childrens postnatal weight gain differently but also that parity and mode of feeding influenced weight velocity of female (β ± s.e. = −0.31 ± 0.11 kg, p = 0.005; β ± s.e. = −0.37 ± 0.11 kg, p < 0.001) but not male offspring. Collectively, our findings imply that maternal resource allocation to consecutive offspring increases after a male firstborn. The absence of this finding in formula fed children suggests that this observation could be mediated by breast milk. Our results warrant further mechanistic and epidemiological studies to elucidate the role of breastfeeding on the programming of infant growth as well as of metabolic and cardiovascular diseases, with potential implications for tailoring infant formulae according to sex and birth order. |
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| Keywords: | infant weight breast milk breastfeeding anthropology infant growth |
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