Cohort profile: the Maternal-Infant Research on Environmental Chemicals Research Platform (Lay Summary)

Arbuckle TE, Fraser WD, Fisher M, Davis K, Liang CL, Lupien N, Bastien S, et al. Paediatric & Perinatal Epidemiology. 2013 Jul;27(4):415-25. doi: 10.1111/ppe.12061

The two key aims of the MIREC Study are to obtain national biomonitoring data for pregnant women and their newborn infants, and to investigate the potential health effects that prenatal exposure to environmental chemicals may have on pregnancy and infant health. Biomonitoring in this context can be defined as the measurement of a chemical substance in the body’s tissues or fluids. The measurements are usually taken in blood and urine, and sometimes in hair, saliva, or breast milk.

In the MIREC Study, led by researchers at Health Canada and CHU Sainte-Justine in Montreal, samples of blood, urine, hair, and breast milk, were collected and analyzed from the roughly 2,001 women recruited from 10 cities across Canada. Samples of umbilical cord blood and infant meconium were also collected following the birth of the women’s infants.

Questionnaires completed during pregnancy and after the babies’ birth collected information on age, education, occupation, life style, medical history, environmental exposures, and diet. The biospecimen samples collected during the first trimester of pregnancy have been analyzed for several environmental chemicals (for example, the metals lead, mercury, cadmium, and arsenic), as well as nutrients. Additional samples were stored in the study’s Biobank so that further analyses could be done at a future time. In addition, research studies were initiated on some of the MIREC children, which have focused on the child’s development from infancy up to age 5. These “follow-up” studies were called MIREC-ID (infant development from birth to 6 months), MIREC-CD3 (child behaviour at age 3) and MIREC-CD Plus (biomonitoring and growth up to age 5, and neurodevelopment at age 3). The complete set of MIREC research studies as well as the Biobank is known as the MIREC Research Platform.

In the initial MIREC Study, of the 8,716 women approached at early-prenatal clinics, 5,108 were eligible and 2,001 (39%) agreed to participate. In comparison to women giving birth in Canada overall, the MIREC participants tended to smoke less (5.9% vs. 10.5%), be older (average age of 32.2 vs. 29.4 years), and have a higher level of education (62.3% vs. 35.1% with a university degree).

While the MIREC Study is smaller in number of participants than several international studies, it has some of the most extensive data on prenatal exposure to environmental chemicals in the world. The samples, questionnaires, laboratory analyses, follow-up studies and Biobank will make the MIREC Research Platform an important resource for investigating possible health effects of prenatal exposure to environmental chemicals. As well, Health Canada will use the results of the MIREC Study to inform assessments of potential health risks and their effective management, especially in relation to exposures to environmental chemicals during pregnancy.