Abstract
BackgroundPreterm birth is a significant public health concern and exposure to phthalates has been shown to be associated with an increased odds of preterm birth. Even modest reductions in gestational age at delivery could entail morbid consequences for the neonate and analyzing data with this additional information may be useful. In the present analysis, we consider gestational age at delivery as our outcome of interest and examine associations with multiple phthalates.MethodsWomen were recruited early in pregnancy as part of a prospective, longitudinal birth cohort at the Brigham and Women’s Hospital in Boston, Massachusetts. Urine samples were collected at up to four time points during gestation for urinary phthalate metabolite measurement, and birth outcomes were recorded at delivery. From this population, we selected all 130 cases of preterm birth (< 37 weeks of gestation) as well as 352 random controls. We conducted analysis with both geometric average of the exposure concentrations across the first three visits as well as using repeated measures of the exposure. Two different time to event models were used to examine associations between nine urinary phthalate metabolite concentrations and time to delivery. Two different approaches to constructing a summative phthalate risk score were also considered.ResultsThe single-pollutant analysis using a Cox proportional hazards model showed the strongest association with a hazard ratio (HR) of 1.21 (95% confidence interval (CI): 1.09, 1.33) per interquartile range (IQR) change in average log-transformed mono-2-ethyl-5-carboxypentyl phthalate (MECPP) concentration. Using the accelerated failure time model, we observed a 1.19% (95% CI: 0.26, 2.11%) decrease in gestational age in association with an IQR change in average log-transformed MECPP. We next examined associations with an environmental risk score (ERS). The fourth quartile of ERS was significantly associated with a HR of 1.44 (95% CI: 1.19, 1.75) and a reduction of 2.55% (95% CI: 0.76, 4.30%) in time to delivery (in days) compared to the first quartile.ConclusionsOn average, pregnant women with higher urinary metabolite concentrations of individual phthalates have shorter time to delivery. The strength of the observed associations are amplified with the risk scores when compared to individual pollutants.
Highlights
Preterm birth is a significant public health concern and exposure to phthalates has been shown to be associated with an increased odds of preterm birth
We recently demonstrated clear associations between maternal urinary phthalate metabolite concentrations averaged from multiple time points during pregnancy and increased odds of preterm birth in a nested case-control study (N = 130 cases, N = 352 controls) of women who delivered at the Brigham and Women’s Hospital in Boston [14]
Summary statistics for the study population with respect to demographic characteristics such as race, education, maternal age, and health insurance status can be found in Additional file 1: Table S2
Summary
Preterm birth is a significant public health concern and exposure to phthalates has been shown to be associated with an increased odds of preterm birth. Exposure to phthalates in utero has been linked to adverse birth outcomes as well, including altered reproductive tract development in male infants [8], neurodevelopment in both sexes [9, 10], and both prematurity and small size at birth [11,12,13,14]. Preterm birth, defined as delivery before 37 weeks completed gestation, is a important endpoint of interest due to: 1) its contribution to neonatal mortality and morbidity and consequent cost to society; 2) the apparent increase in rates over the last three decades; and 3) poorly understood causes and lack of effective interventions [15]. Is preterm birth the leading cause of perinatal and infant mortality, but it is associated with adverse developmental outcomes in children, including chronic conditions such as cardiovascular disease and endocrine disorders [15,16,17]. Research to uncover contributing causes, those in connection with environmental contaminant exposures, is a public health priority [18]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
