Background
Few studies, and none in Canada, have examined the relation between maternal smoking, alcohol consumption and drug dependence during pregnancy and early neonatal morbidity.
Methods
We analyzed records of singleton live births in Alberta, Canada. Markers of neonatal morbidity were Apgar scores (<7 at 5 minutes postpartum) and resuscitation measures (2001-2005, N=191,686), and neonatal intensive care unit (NICU) admissions (2002-2005, N=154,924). Logistic regression was used to estimate odds ratios (ORs) for self-reported substance use and maternal health before conception, adjusting for maternal age, parity, year and fetal gender. Univariate ORs and population-attributable fractions were computed with and without correction for under-reporting of substance use.
Results
Maternal smoking during pregnancy was the most prevalent risk factor, affecting 20% of mothers by self-report, with the figure being possibly twice as high once corrected for under-reporting. Smoking (ORs 1.2), alcohol consumption (ORs 1.2-1.5) and drug dependence (ORs 1.7-2) by the mother during pregnancy were associated with increased risk for each of the markers of early neonatal morbidity (p<0.05, after correcting for covariates). Eliminating the most common among these risk factors, maternal smoking, would prevent 10-15% of each of the three neonatal morbidity markers. Other recorded factors related to mother’s pre-conception health, despite some strong associations, were responsible for only a small proportion of cases.
Discussion
We conclude that in preventing early neonatal morbidity among singleton births in Alberta, control of maternal smoking, the most common of the potentially modifiable risk factors, remains an important goal.