Just one or two cigarettes a day before or during pregnancy is linked to serious health problems in newborns

Even light smoking of just one to two cigarettes per day, before or at any time during pregnancy, is significantly associated with serious health problems in newborns, according to research published online in the Journal of Epidemiology and Community Health.

The findings add to evidence indicating that women who want to become pregnant or who are pregnant should stop smoking to protect the health of their newborn, the researchers say.

The number of deaths and serious health problems among newborns has fallen sharply, largely due to improvements in maternity care. But admission to a neonatal intensive care unit is not uncommon, and furthermore, any neurodevelopmental disorders can persist into adulthood, the researchers say.

In the US, approximately one in ten pregnant women smoke, and it is well known that smoking during pregnancy is associated with increased risks of preterm birth, low birth weight and restricted growth in the womb.

But less known is whether the timing and intensity of maternal cigarette smoking can affect the newborn. This is important because many women think it’s OK to smoke cigarettes before conception or in the first three months of pregnancy, or that light smoking is unlikely to be harmful, the researchers point out.

To investigate this further, they used national birth certificate data from the US National Vital Statistics System (NVSS) from 2016 to 2019, which included a total of 15,379,982 recorded live births.

After excluding multiple births, women who had high blood pressure or diabetes before pregnancy, or without information about cigarette smoking in the three months before and during their pregnancy, 12,150,535 mother-infant pairs were available for data analyses.

Of these couples, just over 9%, 7%, 6%, and just under 6% of mothers reported smoking cigarettes before pregnancy, in the first, second, and third trimesters, respectively. Smoking intensity was classified as 0, 1–2, 3–5, 6–9, 10–19, and 20 or more cigarettes/day.

The women who smoked had more risk factors for newborn health problems: they tended to be younger, non-Hispanic white, unmarried and obese, and had low education levels, more previous births and fewer prenatal care visits.

Major health problems in newborns were defined as: the need for assisted ventilation immediately after delivery; assisted ventilation for more than six hours; NICU admission for continuous mechanical ventilation; surfactant replacement therapy; suspected sepsis; and seizures or serious neurological problems.

The prevalence of all these problems was just under 9.5%.

Smoking before pregnancy or in any of the three trimesters of pregnancy was associated with an increased risk of serious health problems in newborns, individually or combined, after adjusting for potentially influential factors including age, ethnicity and weight (BMI) before pregnancy. pregnancy.

The risk of more than one major health problem in newborns if the mother smoked before pregnancy was 27% higher, and 31-32% higher if she smoked at any time during her pregnancy.

And for individual components, for example, the risk of admission to the neonatal intensive care unit was 24% higher if the mother smoked before pregnancy, and 30-32% higher if she smoked during her pregnancy.

As for timing, women who smoked only before pregnancy or only during the first, second or third trimester were more likely that their newborn would experience more than one major health problem than women who did not smoke at any time.

After adjusting for potentially influential factors, these odds were 12%, 23%, 40%, and 21% higher, respectively.

Even light smoking (1 to 2 cigarettes per day) was associated with an increased risk of serious health problems in newborns.

For example, among mothers who smoked 1 to 2 cigarettes per day before pregnancy, the risk was 16% higher, rising to 31% higher if they smoked 20 or more cigarettes per day.

And the risk of intensive care admission for their newborn was 13% higher with a daily count of 1 to 2 cigarettes, rising to 29% higher with 20 or more cigarettes.

This is an observational study and as such no firm conclusions can be drawn about cause and effect, with the pre-pregnancy data not distinguishing between those who had smoked at any time in the previous three months and those who had smoked for the entire period had. the researchers acknowledge. There was also no information on passive exposure to tobacco smoke.

Nevertheless, they conclude that their findings indicate that there is “no safe period and no safe level of cigarette smoking shortly before or during pregnancy” and “reemphasize the need to prevent smoking initiation for non-smokers and to to promote smoking cessation for smokers. .”