The IMPACT of Tobacco Smoking On Preterm BIRTH and LOW BIRTH Weight: KEY Elements in Strategy of Intervention

Introduction: Preterm birth (< 37 weeks, PTB) and low birth weight (< 2500 gram, LBW) are serious public health concerns with frequency 9.0% and 8.4% in Hungary. Tobacco smoking heavily impacts PTB and LBW alike, however smoking expectant mothers are different by their socio-economic environment and behavioral patterns. Related to these circumstances, there are distinct levels of addiction and tobacco smoke exposition that must be taken in account while planning targeted intervention programs.  

Methods: We collected data of women delivered in 2009 and 2011 in the most underdeveloped four north-eastern counties of Hungary. Our sample (n=11,941) represents 81.0% of the target population.  Medical data were taken over from obstetrical ward records and registers of the local Maternity and Child Health Care. For in-person data collection we used assisted questionnaires. Statistical analysis (Chi-square probe with OR and 95%CI at significance level α ≤0.001) was performed by SPSS 20.0 program.  

Results: Women prior to pregnancy were smoking in 41.7%. When they learned they were pregnant, 36.8% decided for prompt cessation, 43.8% decreased the number of consumed cigarettes, but 19.3% continued the habit without any changes. The never smokers’ PTB and LBW rate was 6.4% and 5.9% respectively. Among those who smoked during the pregnancy, but already attempted cessation the rates were 7.8% and 9.4%. Finally, the rates of those who never attempted it were 13.0%-15.9%. When comparing women who never tried to quit smoking with those having at least one attempt in their history, the risk was significantly higher (OR_PTB=1.77; 95%CI: 1.47-2.12, OR_LBW=1.83; 95%CI: 1.55-2.17). Heavily dependent persons (>20 cigarettes/day) had a considerably greater risk of PTB and LBW when compared with those smoking only 10 cigarettes (OR_PTB=1.6; 95%CI: 1.05-2.45, OR_LBW=1.77; 95%CI: 1.22-2.57). 31.5% of smoking pregnant women were consuming more cigarettes in the first than the rest hours of the day and 26.0% out of them lighted up the first cigarette in the first 30 minutes. Comparing heavily dependent smokers with non-smokers the risk of PTB and LBW was significantly increased (OR_PTB=1.79; 95%CI: 1.54-2.01, OR_LBW=2.67; 95%CI: 2.31-3.08).

Conclusions: The rate of smoking women also during the pregnancy is very high in Hungary’s underdeveloped regions. A considerable part of these women belong to the heavily dependent category. They are at higher risk of PTB or LBW when compared even with the average smoking pregnant population. Based on our results, cessation programs also in the groups of highest levels of dependency must be tried even in seemingly hopeless situations.