Associations of glyphosate and aminomethylphosphonic acid (AMPA) concentrations with birth outcomes in pregnant women from the Midwestern U.S.

BACKGROUND: Pregnant women are ubiquitously exposed to the herbicide glyphosate and its major metabolite aminomethylphosphonic acid (AMPA). Therefore, we examined associations of glyphosate and AMPA with birth outcomes. METHODS: Pregnant women from the Illinois Kids Development Study (I-KIDS) participating in this pilot study (n = 300) provided first-morning urine samples at median 13-weeks gestation for glyphosate and AMPA measurement. We calculated gestational-age-at-birth using the last menstrual period after ultrasound confirmation, abstracted birthweight from electronic medical records, and calculated sex-specific birthweight-for-gestational-age z-scores (BWz). We measured birth length (cm) and anogenital distance (AGD) within 24 h of birth and calculated the anogenital index (AGI, mm/m) by dividing each AGD value (in mm) by the body length (in m). Multivariable linear regression models evaluated associations of glyphosate or AMPA with birth outcomes and differences in associations by newborn sex. RESULTS: In all newborns, only 2-fold higher AMPA was associated with -0.07 cm shorter birth length (95 %CI: -0.16, 0.02). In males, each 2-fold higher glyphosate was associated with -0.06 lower BWz (95 % CI: -0.13, 0.01), -0.14 cm shorter birth length (95 %CI: -0.31, 0.04), and 0.63 longer AGIlong (95 %CI: -0.19, 1.44). In females, each two-fold higher glyphosate was associated with 0.54 longer AGIlong (95 %CI: -0.16, 1.25). AMPA was associated with 0.61 (95 %CI: -0.01, 1.24) and 0.48 (95 %CI: 0.02, 0.94) longer AGIlong in males and females, respectively. Some associations gained precision in sensitivity analyses removing infants born preterm or after controlling for gestational-age-at-birth. CONCLUSIONS: Glyphosate or AMPA were associated with smaller birth size and longer AGIlong, with evidence of sexual-dimorphism, although most findings were imprecise. Larger studies are needed, including those that consider implications of these findings for child lifelong health.