Associations of prenatal urinary phthalate exposure with preterm birth: the Maternal-Infant Research on Environmental Chemicals (MIREC) Study
- DOI
- Language of the publication
- English
- Date
- 2020-05-21
- Type
- Article
- Author(s)
- Hu, Janice M. Y.
- Arbuckle, Tye E.
- Janssen, Patricia
- Lanphear, Bruce P.
- Braun, Joseph M.
- Platt, Robert W.
- Chen, Aimin
- Fraser, William D.
- McCandless, Lawrence C.
- Publisher
- Springer
Abstract
Objectives To examine the relation between prenatal urinary phthalate metabolite concentrations and preterm birth (PTB). Methods The data were drawn from the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a pan-Canadian cohort of 1857 pregnant women enrolled between 2008 and 2011. We quantified urinary concentrations of 7 phthalate metabolites that were detected in > 70% of urine samples collected during the first trimester. Gestational age was obtained from either the last menstrual period or early ultrasound. We used Cox proportional hazard models to examine the associations of urinary phthalate metabolite concentrations, plus the molar sum of di-2-ethylhexyl phthalate metabolites (∑DEHP), with time to delivery before 37 weeks of gestation. We also examined PTB by clinical presentation. PTBs presented with either spontaneous labour or premature rupture of the membrane were considered spontaneous PTB (sPTB). Additionally, we used multiple linear regression to model changes in mean gestational age in relation to phthalate exposure. Results We found no evidence of an association between first trimester phthalate metabolite concentrations and PTB among the MIREC study participants. For example, each 2-fold increase in any of the 7 phthalate concentrations or ∑DEHP was associated with hazard ratios (HRs) for PTB ranging from 0.95 to 1.07 with 95% confidence intervals including the null. An assessment of non-linear trends showed some evidence of non-monotonic dose-response relationships between phthalates and PTB. Furthermore, male infants exposed to MCPP showed higher sPTB risk compared with female infants. Conclusion Phthalate exposure during early pregnancy is not clearly associated with the risk of PTB among this Canadian population.
Plain language summary
Health Canada helps to protect the health of Canadians by assessing and managing the risks associated with exposure to environmental chemicals. Phthalates are a group of chemicals used in plastics to soften and increase flexibility and in a number of consumer products such as cosmetics and fabrics. Some research has suggested that exposure to elevated levels of phthalates during pregnancy may result in a higher risk of preterm delivery. To examine the relation between phthalates and risk of preterm birth, data collected in the Maternal-Infant Research on Environmental Chemicals (MIREC) were analyzed. Urinary concentrations of 7 phthalates were measured in 1857 women during the first trimester of pregnancy and the women were followed through delivery of their infant. Gestational age at delivery was determined by date of last menstrual period or early ultrasound. The study found no clear evidence of an association between phthalates and preterm births. There was some evidence that women with higher urinary concentrations of MCPP (one of the phthalates) had a slightly higher risk of delivering prematurely if the infant was male, compared to a female birth. In conclusion, this study found little evidence to suggest that higher urinary concentrations of phthalates in early pregnancy are associated with increased risk of preterm birth. This research was led by a PhD student at Simon Fraser University.
Subject
- Health,
- Health and safety