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The relationship between active/passive smoking and spontaneous preterm birth: Data from a multicenter study
F S Cavichiolli1, A Borovac-Pinheiro1, G J Lajos1
1Department of Obstetrics and Gynecology, School of Medicine, University of Campinas, Campinas, São Paulo, Brazil.
Insights
This study found no confirmed link between smoking during pregnancy and spontaneous preterm birth. Neither active nor passive smoking increased the incidence of spontaneous preterm birth or adverse neonatal outcomes.
Area of Science:
- Obstetrics and Gynecology
- Neonatal Health
- Public Health
Background:
- Prematurity is a leading cause of under-5 mortality, with smoking a known risk factor.
- Establishing a concrete link between smoking and spontaneous preterm birth (SPB) remains challenging.
- Understanding the impact of active and passive smoking on SPB is crucial for maternal and child health.
Purpose of the Study:
- To investigate the association between active and passive smoking and spontaneous preterm birth.
- To analyze sociodemographic, birth, and neonatal data in relation to smoking status during pregnancy.
Main Methods:
- A multicenter, cross-sectional study in 20 Brazilian maternity hospitals (2011-2012).
- Inclusion of 5295 pregnant participants and their preterm infants.
- Statistical analysis using frequencies, percentages, chi-squared test, and stepwise comparisons.
Main Results:
- 13.5% of pregnant individuals were active smokers, and 31.6% were exposed to passive smoke.
- Higher incidence of SPBs observed in active smokers (61.2%) and passive smokers (61.2%) compared to non-smokers (48.4%).
- Multivariate analysis did not establish a causal relationship between smoking and SPB.
Conclusions:
- The study did not confirm an increased risk of spontaneous preterm birth due to smoking during pregnancy.
- Passive smoking exposure did not correlate with an increased incidence of SPB or adverse neonatal outcomes.
Background:
Prematurity is considered to be the leading cause of death in children under 5 years of age, with one child dying every 2 s. Smoking is known to be one of the factors associated with prematurity, with both immediate and late consequences. However, it is difficult to obtain concrete data on the relationship between smoking and spontaneous preterm birth.
Objective:
The aim of this study was to evaluate the influence of active and passive smoking on spontaneous preterm birth.
Methods:
This was a multicenter, cross-sectional complementary study that included data on preterm births in 20 maternity hospitals in Brazil between 2011 and 2012. The relationship between smoking category (people who smoke [PWS]; people who smoke indirectly [PWSI]; and people who do not smoke [PWDNS]) and sociodemographic characteristics, birth, and neonatal data was assessed. Statistical analysis was performed using frequencies, percentages, the χ2 test, and stepwise comparisons, with a significance level of 5%.
Results:
The original study included 5295 pregnant participants and their preterm infants. There were 1491 spontaneous preterm births (SPBs); 1191 preterm rupture of membranes; 1468 therapeutic preterm births; and 1146 term births. The proportion of women who were PWS during pregnancy was 13.5%, and 31.6% were PWSI. Pregnant individuals who smoked and who smoked indirectly had a higher incidence of SPBs (61.2%) compared with PWDNS (48.4%; P < 0.0001); however, multivariate analysis did not confirm causality.
Conclusions:
This study did not confirm that smoking during pregnancy increases the risk of SPB. PWSI also did not have an increased incidence of spontaneous preterm birth or adverse neonatal outcomes.
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