To compare use of electronic nicotine delivery systems (ENDS) with nicotine replacement therapies (NRTs) on risk of cigarette smoking relapse by people who had already quit cigarettes.

Prospective cohort study.

The American Cancer Society Cancer Prevention Study-3, a nationwide US cohort with follow-up every 3 years beginning in 2015.

Adults who in 2015 had already quit smoking (n=3112) or were smoking (n=1018) and who in 2018 reported past or current exclusive use of ENDS or NRT and provided smoking status.

Relapse to cigarette smoking in 2018 among people who were already quit in 2015, and abstinence from cigarettes in 2018 among people who were smoking in 2015.

Among respondents who had already quit in 2015, the unadjusted risk of relapse in 2018 was approximately three times greater for those who reported past exclusive ENDS versus past exclusive NRT use (11.2% vs 3.9%; relative risk (RR)=2.90, 95% CI 2.12 to 3.98). This association remained significant in a multivariable-adjusted model (RR=2.09, 95% CI 1.49 to 2.92). Among those smoking in 2015, the unadjusted likelihood of abstinence in 2018 was higher for those who reported current ENDS versus NRT use (RR=1.35, 95% CI 1.01 to 1.80), but the multivariable model adjusted for smoking frequency indicated no difference in abstinence (RR=1.38; 95% CI 0.93 to 2.05).

ENDS use was associated with greater relapse risk than NRT among people who had already quit. Although ENDS may support shorter-term cessation, further long-term observational research is needed to clarify relapse risks associated with ENDS relative to NRT.

Adolescent pregnancy is a global issue. Early childbearing is strongly linked to poverty and negative health outcomes, including increased neonatal death risk. This study explores spatial patterns of adolescent pregnancies and neonatal deaths and their association with socioeconomic characteristics.

This population-based study used spatial analysis techniques to investigate the geographical distribution of adolescent pregnancies, socioeconomic characteristics and neonatal mortality rate (NMR).

The 645 municipalities of State of Sao Paulo, Brazil.

All live births to mothers residing in the State of Sao Paulo, Brazil, between 2004 and 2020.

The socioeconomic indicators used were: municipal human development index and per capita income (PCI). Spatial patterns were assessed for spatial autocorrelation (Moran’s I, LISA), and smoothed using local Bayesian estimation. Spearman’s correlation was used to ascertain the relationship between the percentage of live births to adolescent mothers and socioeconomic indexes. This calculation was also undertaken between different maternal age groups of NMR.

The study analysed over 10 million live births, with 14.3% attributed to adolescent mothers. Spatial analysis revealed significant clustering of adolescent pregnancies, strongly associated with lower socioeconomic indicators. NMR also exhibited spatial clustering, particularly after smoothing. Statistically significant differences were observed in PCI medians between high–high and low–low clusters for adolescent births. High and low incidence areas of NMR, both in all maternal ages and stratified by adolescent and non-adolescent mothers, demonstrated considerable overlap.

The results indicated the existence of clustering areas of adolescent pregnancy and neonatal deaths and suggested that the prevalence of births to adolescent mothers is not distributed equally and is higher in lower socioeconomic developed areas.