Maternal smoking during pregnancy increases the risk for adult-onset asthma in offspring, according to a study published in the European Respiratory Journal.
The study was an analysis of questionnaire and clinical data of 5200 participants in the Northern Finland Birth Cohort 1966 Study who were free of physician-diagnosed asthma by 31 years of age. Only participants who had complete information on their mothers’ smoking status during the last 3 months of pregnancy and information on asthma incidence at 31 years and 46 years were included.
Prenatal and perinatal environment data were collected with questionnaires and clinical examinations conducted during the mothers’ clinical pregnancy visit. Follow-up data for offspring were collected at ages of 31 and 46 years. Questionnaires were also used to collect self-reported physician-diagnosed asthma and self-reported asthma data at age 46 years.
In offspring, the cumulative incidence of asthma between ages 31 and 46 years was 5.1% for men and 8.8% for women. The risk for asthma between ages 31 and 46 years in offspring was found to be higher in those who had mothers who smoked ≥1 cigarette per day during the last 3 months of pregnancy (adjusted odds ratio [OR], 1.54; 95% CI, 1.04-2.29; P =.033). Gestational smoke exposure was associated with adult-onset asthma in offspring who had not been previously diagnosed with asthma (OR, 9.63; 95% CI, 2.28-40.67; P =.002) or had not had past cough with wheeze (OR, 3.21; 95% CI, 1.71-6.05; P <.001).
An association between gestational smoke exposure during the last 3 months of pregnancy and the ratio of forced expiratory volume during the first second to forced vital capacity in offspring at age 31 years was established in an adjusted analysis (adjusted beta coefficient -0.056; t= -3.24; 95% CI, -0.020 to -0.005; P =.001). Gestational smoke exposure was associated with adult-onset asthma in offspring with the haplotype rs11702779-AA for the RUNX1 gene (OR, 5.53; 95% CI, 2.11-14.52; P =.001).
Limitations of this study include the lack of objective markers for smoking during pregnancy and the lack of adjustment for maternal smoking exposure after birth and throughout childhood.
“These results could reflect early vulnerability of offspring´s airways to environmental tobacco smoke exposure and its putative long-term effects,” noted the study authors.
Toppila-Salmi S, Luukkainen AT, Xu B, et al. Maternal smoking during pregnancy affects adult onset of asthma in offspring: a follow up from birth to age 46 years [published online April 27, 2020]. Eur Respir J. doi: 10.1183/13993003.01857-2019