By Lisa Rapaport
(Reuters Health) – Children whose mothers used smokeless tobacco during pregnancy have higher blood pressure by the time they’re 5-6 years old compared to peers whose mothers avoided tobacco, a small Swedish study finds.
Researchers examined blood pressure in 21 kids exposed in the womb to snus, a moist powdered smokeless tobacco, and 19 children without any prenatal tobacco exposure.
In kids exposed to snus, systolic blood pressure – the “top number” – averaged 4.2 mmHG (millimeters of mercury) higher than in children without any prenatal tobacco exposure, showing higher pressure exerted by blood against artery walls when the heart beats.
“We don´t know if the increased systolic blood pressure has implications for cardiovascular health in later life, that remains to be studied,” said Dr. Felicia Nordenstam, lead author of the study and a researcher the Karolinska Institute in Stockholm.
But no amount of tobacco exposure is known to be safe during pregnancy, Nordenstam said by email.
“Women should abstain from all types of tobacco and nicotine containing products during pregnancy,” Nordenstam said. “If quitting tobacco and nicotine is not an option, cutting down the doses as much as possible is recommended.”
The study also looked at each child’s heart rate, which is controlled by a part of the nervous system that is affected by nicotine. Assessing heart-rate variability (HRV), a measure of the heart’s responsiveness to changing demands, the study team found that children of snus users had poorer HRV.
Researchers didn’t find an association between prenatal snus exposure and “diastolic” blood pressure – the bottom number – which indicates how much pressure the blood exerts on artery walls when the heart is at rest between beats.
Smoking during pregnancy has long been linked to a wide variety of pregnancy complications including preterm births, low birth weight and stillbirth. Kids also have an increased risk of high blood pressure when mothers smoked during pregnancy, previous studies have found.
Pregnant women who used snus were included in the current study only if they used high doses of the tobacco product, providing 48 milligrams or more of nicotine a day, throughout their entire pregnancy. Outcomes for their children were compared to kids of mothers who used no tobacco products at all during pregnancy.
None of the kids in the study had parents who smoked cigarettes during pregnancy or during their early childhood.
The differences in systolic blood pressure between children with and without snus exposure in the study were larger than the 1 to 3 mmHG difference found in some recent studies of cigarette smoking in pregnancy, researchers note in the Journal of the American Heart Association.
Beyond its small size, other limitations of the study include the lack of long-term data to determine whether and how snus exposure during pregnancy might lead to lasting cardiovascular problems for the children.
“The full extent and precise mechanism behind prenatal nicotine exposure and altered cardiac control and blood pressure regulation is not fully understood,” Nordenstam said.
But blood pressure does tend to follow a trajectory that begins in childhood, making kids with even slightly elevated numbers more likely to develop hypertension as adults, researchers note.
SOURCE: https://bit.ly/2OQTqNh Journal of the American Heart Association, online October 16, 2019.