Smoking one to two cigarettes per day before or during pregnancy increases the risk of severe neonatal complications

A study published in August 2024 in the Journal of Epidemiology & Community Health[1], based on US data, concerning the consequences of maternal smoking before and during pregnancy on the occurrence of a set of severe neonatal diseases shows that consumption by mothers before or during pregnancy of 1 to 2 cigarettes per day is associated with a significant increase in the frequency of occurrence of these severe neonatal diseases in their children compared to those of non-smoking women.

Maternal smoking before and during pregnancy is associated with many health complications: miscarriages, ectopic pregnancies, intrauterine growth retardation, premature births, sudden infant death, etc.

The researchers used national birth certification data from the U.S. National Vital Statistics System (NVSS) collected from 2016 to 2019, corresponding to 15,379,982 registered live births. After excluding multiple births, women who had high blood pressure or diabetes before pregnancy, or who did not provide information on smoking in the 3 months before and during pregnancy, 12,150,535 mother-child pairs were available for data analysis. Among the mothers participating in the study, 9.3 % smoked before pregnancy, while 7 % smoked during the first trimester, 6 % during the second trimester, and 5.7 % during the third trimester.

For this study, a composite index of severe neonatal illness was used based on the occurrence of the following complications: need for assisted ventilation immediately after delivery, assisted ventilation for more than 6 hours, admission to neonatal intensive care for continuous mechanical ventilation, surfactant replacement therapy, suspected sepsis, and seizures or severe neurological problems. The overall prevalence of all these problems in neonates was slightly lower at 9.5% in this study.

Risks of neonatal health complications even from smoking one to two cigarettes per day

Smoking before or during each of the three trimesters of pregnancy was associated with an increased incidence of these major neonatal health problems. Newborns were 27% more likely to have them if their mother had smoked in the three months before pregnancy, and 31% more likely if she smoked at any time during pregnancy.

From an analytical perspective, the risk of admission to neonatal intensive care, for example, was 24 % higher for newborns whose mothers smoked before pregnancy, and 30 to 32 % higher if they smoked during pregnancy, compared with newborns of non-smoking mothers.

Finally, smoking one or two cigarettes per day before or during pregnancy increased the risk of all of these health problems in newborns by 16%; the risk was 31% higher in those born to mothers who smoked 20 or more cigarettes per day. For example, the risk of admission to neonatal intensive care was 13% higher for newborns whose mothers smoked 1 to 2 cigarettes per day, and 29% higher for those whose mothers smoked 20 or more cigarettes per day, compared with newborns born to nonsmoking mothers.

The authors point out some limitations to their study. First, the NVSS only collected data for the 3 months preceding pregnancy, which does not allow us to distinguish between women who had never smoked and those who had stopped before this period. Second, the NVSS VS did not collect information on women's possible exposure to passive smoking, which does not allow us to assess its possible role in the occurrence of these neonatal complications.

They conclude that their results suggest "that there is no risk-free period or threshold for cigarette consumption shortly before and during pregnancy" and stress "that women of reproductive age should not smoke."

In France, the2021 national perinatal survey, specifies that the proportion of women reporting tobacco consumption in the 3rd trimester of pregnancy is 12.2%, a figure which is certainly falling, but which remains very high compared to the rest of Europe where 8.1% of women report smoking in the 3rd trimester.^th quarter[2].

©Tobacco Free Generation

AE

[1] Yang L, Yang L, Wang H, et al Maternal cigarette smoking before or during pregnancy increases the risk of severe neonatal morbidity after delivery: a nationwide population-based retrospective cohort study J Epidemiol Community Health Published Online First: 20 August 2024. doi: 10.1136/jech-2024-222259

[2] Lange S, Probst C, Rehm J, Popova S. National, regional, and global prevalence of smoking during pregnancy in the general population: a systematic review and meta-analysis. Lancet Global Health. 2018 Jul;6(7):e769-e776. doi: 10.1016/S2214-109X(18)30223-7. Epub 2018 May 31. PMID: 29859815.