Prenatal smoking among adolescents and risk of fetal demise before and during labor.

STUDY OBJECTIVE

To investigate the relationship between smoking during pregnancy and the occurrence of stillbirth phenotypes among adolescent mothers.

DESIGN

Retrospective cohort

SETTING

Singleton births in Missouri from 1978 through 1997.

PARTICIPANTS

Two groups of "younger" (<15 years) and "older" (15-19 years) adolescent mothers were compared to "mature" mothers (age 20-24 years).

MAIN OUTCOME MEASURES

Cox Proportional Hazards Regression models generated adjusted risk estimates of the association between intrauterine nicotine exposure and the risk of total, antepartum, and intrapartum stillbirth in each age group.

RESULTS

Approximately 32% (N=205,887) of the total 633,849 singleton births analyzed were among adolescent mothers. The overall prevalence of smoking was 31.2%, with the lowest prevalence (14.1%) among the youngest mothers while older adolescents had the highest (31.7%). The risk for intrapartum stillbirth among smoking adolescents <15 years of age was twice the risk for older adolescent and mature mothers. The risk of intrapartum stillbirth among smokers decreased as maternal age increased: [adjusted hazard ratio (AHR), 95% confidence interval (CI) for young mothers: 4.0, 95%CI=0.6-28.7; for older adolescents AHR=1.5, 95%CI=1.1-2.1 and for mature mothers AHR=1.8, 95% CI=1.4-2.2], respectively.

CONCLUSIONS

In utero tobacco exposure has maternal age-related differential and lethal effects on the fetus. Young maternal age tends to potentiate these effects. There is a public health need to develop appropriate smoking cessation messages targeted specifically to this high risk group.