Exposure to cigarette smoke in utero: comparison of reports from mother and daughter.

BACKGROUND

Smoking during pregnancy has been associated with asthma, obesity, and decreased cognitive functioning in the offspring. To study the role of in utero smoking exposure in offsprings' adult health outcomes, it may be necessary to rely upon reports by the offspring themselves.

METHODS

We studied 34,949 mother-daughter pairs participating in the Nurses' Health Study II for whom data on the daughter's early passive cigarette smoke exposure had been obtained from both mother and daughter. We calculated sensitivity and specificity of daughter's early exposure to smoke (using mother's report as the gold standard), as well as kappa statistics. Mother and daughter reports were also analyzed as risk factors for asthma and birthweight to demonstrate face validity.

RESULTS

Sensitivity of daughters' reported prenatal exposure ranged from 74% to 85%, while specificity was between 90% and 95% (kappa = 0.72-0.81). Daughter's reported childhood exposure as a proxy for mother's report of smoking during pregnancy had a sensitivity of 89% and specificity of 88%. Results were similar for daughter's report of father's smoking during her childhood. Maternal smoking during pregnancy is consistently associated with reductions in offspring birthweight, and with asthma risk in offspring. The daughter's risk of being very low (<1500 g) or low birthweight (<2500 g) or of having asthma were similar when exposure was defined according to mother's report, daughter's report of fetal smoke exposure, and daughter's report of mother's smoking during childhood.

CONCLUSIONS

Daughter's report of mother's smoking prenatally and in childhood are good proxy measures for mother's own report of smoking during pregnancy.