Abstract
Preterm birth (PTB) is a leading cause of newborn deaths and morbidities. The pregnancy risk assessment monitoring system (PRAMS) from the U.S., and the maternity experiences survey (MES) from Canada, which was modeled from PRAMS, were used to examine between-country differences in risk factors of preterm birth. The adjusted risk ratio and population attributable fraction (PAF) were calculated for modifiable and semi-modifiable risk factors of PTB, and all measures were compared between the U.S. and Canada. PTB was defined here as a live singleton birth between 28 and 37 completed weeks gestation (using the clinical gestational age estimate) where the baby was living with the mother at the time of the survey. The PTB risk was 7.6 % (SE = 0.2) in the U.S. and 4.9 % (SE = 0.3) in Canada. The a priori high risk category of factors was almost always more prevalent in the U.S. than Canada, suggesting broad social differences, but individually most of these differences were not associated with PTB. The underlying risk of PTB was generally higher in the U.S. in both the higher risk and referent categories, and the risk ratios for most risk factors were similar between the countries. The primary exception was for recurrence of PTB, where the risk ratio (RR) and PAF were much higher in Canada. We observed between-country differences in both the prevalence of risk factors and the adjusted RR. Further between-country comparisons may lead to important inferences as to the influence of modifiable risk factors contributing to PTB.
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Acknowledgments
We are grateful for the guidance of The PREterm Birth International Collaborative (PREBIC) Epidemiology workgroup for facilitating the relationship between the U.S. and Canadian collaborators. PREBIC is a nonprofit organization, supported by the WHO and the March of Dimes (www.prebic.net). We are also grateful to the PRAMS working group (http://www.cdc.gov/prams/PDF/WorkingGroup_7-2012.pdf ), and to the staff at the Prairie Regional Data Centre for the approval of this project and for making the data available for this project. J.V.G. is supported in part by a NIH training grant in reproductive, perinatal and pediatric epidemiology through Emory University (T32HD052460). A.M. is funded by a fellowship award from the Canadian Institutes of Health Research. S.T. is funded by a health scholar award from Alberta Innovates—Health Solutions.
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Garn, J.V., Nagulesapillai, T., Metcalfe, A. et al. International Comparison of Common Risk Factors of Preterm Birth Between the U.S. and Canada, Using PRAMS and MES (2005–2006). Matern Child Health J 19, 811–818 (2015). https://doi.org/10.1007/s10995-014-1576-y
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DOI: https://doi.org/10.1007/s10995-014-1576-y