Perinatal & Pediatric
Associations of glyphosate and aminomethylphosphonic acid (AMPA) with length of gestation and birth size Kelsi Morris* Kelsi Morris Brad Ryva Maria Cinzori Khyatiben Pathak Patrick Pirrotte Brooke Lovell Susan Schantz Rita Strakovsky
Background: Pregnant women are exposed to the herbicide glyphosate and its major metabolite aminomethylphosphonic acid (AMPA), but their associations with birth outcomes are unclear. We evaluated associations of glyphosate and AMPA with birth outcomes and considered differences by fetal sex and pre-pregnancy BMI (ppBMI).
Methods: Illinois pregnant women (n=300) provided urine samples at median 13 weeks gestation for glyphosate and AMPA assessment. We calculated gestational age at birth using ultrasound-confirmed due date and birth date. We measured body length and head circumference within 24 hours of birth and calculated sex-specific birthweight (BW)-for-gestational-age z-scores (BWz). In primary analyses, we used multivariable linear regression to evaluate associations of specific gravity-adjusted glyphosate or AMPA with birth outcomes. We conducted secondary analyses stratified by fetal sex in which we added a multiplicative interaction term to consider differences by ppBMI.
Results: The median (25th, 75th percentile) birthweight was 3515.3 g (3231.9, 3838.5) and gestational age at birth was 39.4 weeks (38.6, 40.3). Glyphosate levels were lower than in other U.S. women. Overall, each 2-fold increase in glyphosate was associated with -21.4g lower BW (95% confidence interval (CI): -48.7, 5.9) and -0.05 lower BWz (95%CI: -0.11, 0.01). These associations were due to women carrying males (BW: β = -31.2, 95%CI: -63.1, 0.7; BWz: β = -0.06, 95%CI: -0.1, 0.0). Further, in women with overweight or obesity carrying males, each 2-fold increase in glyphosate was associated with -40.7g lower BW (95%CI: -80.8, -0.6) and -0.08 lower BWz (95%CI: -0.2, 0.00). Glyphosate was not associated with other birth outcomes. AMPA was not associated with any birth outcomes.
Conclusion: This pilot study points to differences in associations of glyphosate with fetal growth by fetal sex and maternal ppBMI. Future studies may need to consider underlying mechanisms and implications of our findings.