Maternal smoking during pregnancy and placental abruption risk in Northwest Russia; a MCBR study

О А Харькова, Alexandra Krettek, A M Grjibovski, JØ Odland

European Journal of Public Health, 2016

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DOI 10.1093/eurpub/ckw174.151
Data confidence 70 medium
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Abstract

Background Placental abruption is a pregnancy complication that leads to separation of placental lining from the uterus before delivery. Two-thirds of placental abruptions are accompanied by fetal or neonatal complications, which includes preterm delivery. International studies show that maternal smoking increases the risk of placenta abruption, but the evidence from Russia is limited. We studied whether maternal smoking influences the risk of placental abruption development in Murmansk County, Northwest Russia. Methods We conducted a cohort study with data from the Murmansk County Birth Registry (2006-2011) and included singleton pregnancies (N = 50,698). Placenta abruption was classified according to the International Classification of Diseases tenth revision (code O45). Information on maternal smoking was self-reported and defined as “smokers”, “smokers who quit during pregnancy”, and “non-smokers”. The number of cigarettes smoked daily was categorized as none, 1-5, 6-10, and ≥11. Associations between factors were studied by logistic regression and adjusted for maternal age, education, marital status, ethnicity, residence, parity, alcohol abuse, and year of delivery. Additionally, tests for trends were used for ordinal variables. Results A total 1.2% (95%CI: 1.1-1.3) of women had a placenta abruption during current pregnancy. An increased risk of placental abruption was found among smokers (ORadj=1.28 95% CI: 1.04-1.57) compared with non-smokers. We also found linear relationship between number of cigarettes smoked per day during pregnancy and the risk of placental abruption (ORadj=1.15 95%CI: 1.01-1.32). Conclusions Maternal smoking is associated with placental abruption risk in Murmansk County. Moreover, we found a positive linear association between number of smoked cigarettes per day and risk of placental abruption.