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. 2011 Dec;119(12):1811-6.
doi: 10.1289/ehp.1103579. Epub 2011 Aug 3.

Early-life soy exposure and gender-role play behavior in children

Margaret A Adgent  1 , Julie L Daniels, Lloyd J Edwards, Anna Maria Siega-Riz, Walter J Rogan
Affiliations

Early-life soy exposure and gender-role play behavior in children

Margaret A Adgent et al. Environ Health Perspect. 2011 Dec.

Abstract

Background: Soy-based infant formula contains high levels of isoflavones. These estrogen-like compounds have been shown to induce changes in sexually dimorphic behaviors in animals exposed in early development.

Objective: We examined gender-role play behavior in relation to soy-based and non-soy-based infant feeding methods among children in the Avon Longitudinal Study of Parents and Children.

Methods: We studied 3,664 boys and 3,412 girls. Four exposure categories were created using data from questionnaires administered at 6 and 15 months postpartum: primarily breast, early formula (referent), early soy, and late soy. Gender-role play behavior was assessed using the Pre-School Activities Inventory (PSAI). Associations between infant feeding and PSAI scores at 42 months of age were assessed using linear regression. Post hoc analyses of PSAI scores at 30 and 57 months were also conducted.

Results: Early-infancy soy use was reported for approximately 2% of participants. Mean [95% confidence interval (CI)] PSAI scores at 42 months were 62.3 (62.0, 62.6) and 36.9 (36.6, 37.2) for boys and girls, respectively. After adjustment, early soy (vs. early formula) feeding was associated with higher (less feminine) PSAI scores in girls (β = 2.66; 95% CI: 0.19, 5.12) but was not significantly associated with PSAI scores in boys. The association between soy exposure and PSAI scores in girls was substantially attenuated at 30 and 57 months.

Conclusions: Although not consistent throughout childhood, early-life soy exposure was associated with less female-typical play behavior in girls at 42 months of age. Soy exposure was not significantly associated with play behavior in boys.

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Conflict of interest statement

The authors declare they have no actual or potential competing financial interests.

Figures

Figure 1
Figure 1
Exposure characterization. Participants were classified into four mutually exclusive feeding groups (primarily breast, early formula, early soy, late soy). Participants who did not meet an exposure definition or who had incomplete feeding data were excluded. aOther: formula/baby milk, goat’s milk, follow-on milk, hypoallergenic formula, and cow’s milk. bUnknown: data insufficient to determine breast-feeding duration or milk/formula use through 6 months. cSoy: soy milk or soy formula.
Figure 2
Figure 2
Distribution of 42-month PSAI Scores by sex and feeding group for (A) girls and (B) boys.
See this image and copyright information in PMC

Comment in

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