Maternal diet quality moderates associations between parabens and birth outcomes

Abstract

Background/objective: Maternal paraben exposure and diet quality are both independently associated with birth outcomes, but whether these interact is unknown. We assessed sex-specific associations of parabens with birth outcomes and differences by maternal diet quality.

Methods: Illinois pregnant women (n = 458) provided five first-morning urines collected at 8-40 weeks gestation, which we pooled for quantification of ethylparaben, methylparaben, and propylparaben concentrations. We collected/measured gestational age at delivery, birth weight, body length, and head circumference within 24 h of birth, and calculated sex-specific birth weight-for-gestational-age z-scores and weight/length ratio. Women completed three-month food frequency questionnaires in early and mid-to-late pregnancy, which we used to calculate the Alternative Healthy Eating Index (AHEI)-2010. Linear regression models evaluated sex-specific associations of parabens with birth outcomes, and differences in associations by average pregnancy AHEI-2010.

Results: In this predominately non-Hispanic white, college-educated sample, maternal urinary paraben concentrations were only modestly inversely associated with head circumference and gestational length. However, methylparaben and propylparaben were inversely associated with birth weight, birth weight z-scores, body length, and weight/length ratio in female, but not male newborns. For example, each 2-fold increase in methylparaben concentrations was associated with -46.61 g (95% CI: -74.70, -18.51) lower birth weight, -0.09 (95% CI: -0.15, -0.03) lower birth weight z-scores, -0.21 cm (95% CI: -0.34, -0.07) shorter body length, and -0.64 g/cm (95% CI: -1.10, -0.19) smaller weight/length ratio in females. These inverse associations were more prominent in females of mothers with poorer diets (AHEI-2010 < median), but attenuated in those with healthier diets (AHEI-2010 ≥ median). In newborn males of mothers with healthier diets, moderate inverse associations emerged for propylparaben with gestational length and head circumference.

Conclusions: Maternal diet may moderate associations of parabens with birth size in a sex-specific manner. Additional studies may consider understanding the inflammatory and metabolic mechanisms underlying these findings.

Keywords: Birth size; Gestational length; Head circumference; Maternal diet; Newborn sex; Parabens.

Figure 1.. Adjusted sex-specific associations of urinary specific gravity-adjusted paraben concentrations with birth outcomes by maternal diet quality.

Linear regression models accounted for age, race/ethnicity, parity, pre-pregnancy body mass index, conception season, depression, newborn sex, average pregnancy diet quality, and a three-way interaction (with all corresponding two-way interactions) between paraben, newborn sex, and diet quality. Worse and better diet quality are indicated by the empty and filled shapes, respectively. Data are presented as the change (shape) and 95% CI (vertical solid lines) in gestational length (wk), birth weight (g), birth weight z-score, body length (cm), weight/length ratio (g/cm), and head circumference (cm) for every 2-fold increase in maternal urinary ethylparaben (A, B, C, D, E, F), methylparaben (G, H, I, J, K, L), and propylparaben (M, N, O, P, Q, R) concentrations. Results are presented separately for female (F) and male (M) newborns. Sample sizes for each group can be found in Table 3. CI, confidence interval.