At 5 years old, the children of mothers who smoked in pregnancy had significantly greater carotid intima-media thickness and lower arterial distensibility than did unexposed offspring.
"Moreover, there was a clear positive trend between the number of cigarettes smoked by mothers in pregnancy and adverse vascular health, a finding that adds to the credibility of gestational smoking being causally related to offspring vascular damage," wrote Dr. Caroline C. Geerts and colleagues in a study published online Dec. 26 in the journal Pediatrics.
In what the researchers called the first study to report on prenatal smoking and arterial characteristics in nonsmoking offspring, Dr. Geerts of the University Medical Center Utrecht (the Netherlands), and colleagues looked at 259 children who underwent ultrasound at age 5 years to determine carotid artery intima-media thickness (CIMT) and arterial wall distensibility (Pediatrics 2011 Dec. 26 [doi:10.1542/peds.2011-0249]).
The subject’s mothers had previously completed surveys when their children were 4 weeks of age, answering questions about smoking status at that time and during the pregnancy.
A similar questionnaire was administered at the time of the child’s ultrasound.
The majority of mothers (244 of 259) reported that they did not smoke during pregnancy, according to the questionnaire.
At birth, children born to smokers did not differ significantly from their counterparts in terms of weight, length, or gestational age, although there was a trend for these children to be lighter in weight and shorter.
"There was a clear positive trend between the number of cigarettes smoked by mothers in pregnancy and adverse vascular health."
They were, however, significantly less likely to be breastfed than babies of nonsmoking mothers.
By 5 years, among the 258 children with CIMT values available, children of mothers who smoked during pregnancy (n = 15) had a CIMT that was 18.8 mcm thicker than that of their counterparts.
Additionally, the children of mothers who smoked both during pregnancy and in the postnatal period (n = 11) had an even thicker CIMT (23.3 mcm) compared with that of completely nonexposed children.
In contrast, the children of 16 women who did not smoke in pregnancy but did smoke currently had no differences in CIMT, compared with children of nonsmoking mothers.
The finding was similar when investigators looked at vascular function: The arteries of children whose mothers smoked during pregnancy had significantly (16%) less stretch than did those of nonexposed peers, and the effect was compounded for children whose mothers smoked both during pregnancy and at the 5-year follow-up (19% lower distensibility).
Meanwhile, children of mothers who did not smoke during pregnancy but took it up afterward had no significant difference in distensibility, compared with their unexposed peers.
Finally, the authors found that compared with the children of mothers who smoked five or fewer cigarettes per day during pregnancy, the children of mothers who smoked more than five per day exhibited a statistically significant trend of lower mean arterial distensibility, as well as a nonsignificant trend toward greater CIMT, according to Dr. Geerts.
The authors conceded that the use of nicotine and cotinine as maternal and neonatal hair biomarkers for active smoking would have given a more reliable picture of smoking activity than did the questionnaires.
However, "that technology was unknown at the time of the [study] design, and it is not known if measurements at inclusion (weeks postpartum) accurately reflect smoke exposure in pregnancy," they wrote.
Indeed, "underreporting of smoking cannot be excluded but would most likely mean dilution of the association."
The investigators also added that CIMT and distensibility at age 5 years – known markers of cardiovascular disease risk in adulthood – may not correlate to disease in adulthood.
Such associations "can only be assumed," they added.
The authors stated they had no individual financial relationships relevant to this article to disclose. The study was partly funded by the Netherlands Organization for Health Research and Development, as well as the University Medical Center Utrecht.