Patterns of smoking during pregnancy in Canterbury

To examine the prevalence and patterns of smoking in pregnancy with the object of improving smokefree programmes in the region.

A postal questionnaire on smoking in pregnancy was sent to all 1916 mothers giving singleton births in the Canterbury region over a five month period. There was a 71.7% response rate, however, smokers were significantly under represented. Data from nonresponders was obtained from obstetric records.

Of the total sample, 30% smoked during their last pregnancy. There were significant differences between responders and nonresponders. The responders contained only 60% of all smokers. Nonresponders had twice the incidence of smoking, were more likely to identify as Maori, were younger and had lower birth weights. Nonresponders contained 40% of all smokers. Of the responders, 333 mothers smoked during at least some part of pregnancy: 113 (34%) quit, 168 (50%) cut down, and 48 (15%) made no change. Most (90%) of those who did quit did so during the first trimester. Lighter smokers (less than 10 per day) were more likely to quit or cut down. But smoking rates subsequently increased after the birth.

In Canterbury, 30% of pregnant women smoke. Although 64% indicated a wish to quit and 30% to cut down, this contrasted with what they actually achieved: 34% quit and 50% cut down. Pregnancy influences smoking patterns and is an opportune time for smokefree promotion.