Smoking ban and small-for-gestational age births in Ireland

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Date
2013
Authors
Kabir, Zubair
Daly, Sean
Clarke, Vanessa
Keogan, Sheila
Clancy, Luke
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Public Library of Science
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Abstract
Background: Ireland introduced a comprehensive workplace smoke-free legislation in March, 2004. Smoking-related adverse birth outcomes have both health care and societal cost implications. The main aim of this study was to determine the impact of the Irish smoke-free legislation on small-for-gestationa-age (SGA) births. Methods and Findings: We developed a population-based birthweight (BW) percentile curve based on a recent study to compute SGA (BW < 5th percentile) and very SGA (vSGA-BW < 3rd percentile) for each gestational week. Monthly births born between January 1999 and December 2008 were analyzed linking with monthly maternal smoking rates from a large referral maternity university hospital. We ran individual control and CUSUM charts, with bootstrap simulations, to pinpoint the breakpoint for the impact of ban implementation (=April 2004). Monthly SGA rates (%) before and after April 2004 was considered pre and post ban period births, respectively. Autocorrelation was tested using Durbin Watson (DW) statistic. Mixed models using a random intercept and a fixed effect were employed using SAS (v 9.2). A total of 588,997 singleton live-births born between January 1999 and December 2008 were analyzed. vSGA and SGA monthly rates declined from an average of 4.7% to 4.3% and from 6.9% to 6.6% before and after April 2004, respectively. No auto-correlation was detected (DW =similar to 2). Adjusted mixed models indicated a significant decline in both vSGA and SGA rates immediately after the ban [(-5.3%; 95% CI -5.43% to -5.17%, p < 0.0001) and (-0.45%; 95% CI: -0.7% to -0.19%, p < 0.0007)], respectively. Significant gradual effects continued post the ban periods for vSGA and SGA rates, namely, -0.6% (p < 0.0001) and -0.02% (p < 0.0001), respectively. Conclusions: A significant reduction in small-for-gestational birth rates both immediately and sustained over the post-ban period, reinforces the mounting evidence of the positive health effect of a successful comprehensive smoke-free legislation in a vulnerable population group as pregnant women.
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Keywords
Maternal smoking , Preterm birth , Weight , Exposure , Fetal , Outcomes , Growth , Risk , Legislation , Workers
Citation
Kabir Z, Daly S, Clarke V, Keogan S, Clancy L (2013) Smoking Ban and Small-For-Gestational Age Births in Ireland. PLoS ONE 8(3): e57441. doi:10.1371/journal.pone.0057441