Cardiovascular stress hyperreactivity in babies of smokers and in babies born preterm.
BACKGROUND
Being born preterm, small, and to a mother who smokes are common perinatal complications with major public health implications. Evidence suggests that each affects the body's structure and function in ways that could increase susceptibility to cardiovascular dysfunction later in life. Here, we used 2 routine stress reactivity tests to identify incipient "silent" programming of cardiovascular dysfunction associated with adverse perinatal events.


RESULTS
We studied 29 control babies born at term to nonsmokers, 18 term-born babies of mothers who smoked throughout pregnancy (mean, 15 cigarettes a day), and 31 babies born preterm to nonsmokers. All infants were compared at the same age after conception (ie, at 40 to 42 weeks), during sleep. We analyzed blood pressure (BP) and heart rate responses to breathing 4% CO(2) for 4 minutes or to passive head-up tilt to 60 degrees . BP was measured continuously from a wrist cuff. CO(2) exposure raised heart rate and BP in controls by 10%, and tilt increased their BP by 5%. CO(2) elicited the expected BP but no heart rate response from preterm infants but a much-greater-than-expected BP and heart rate response from babies of smokers. Tilt elicited a 3- to 4-fold greater rise in BP from preterm and tobacco-exposed babies.


CONCLUSIONS
Vascular, cardiac, and blood pressure reactivity is heightened in babies born preterm or to smokers. The findings are consistent with in utero and early postnatal "programming" of human cardiovascular dysfunction by adverse circumstances. This incipient dysfunction may be an early manifestation of processes that lead to other problems or complications later on (eg, higher BP or sudden infant death syndrome).
Department of Women and Child Health, Neonatal Unit, Karolinska Institute, Elevhemmet H1-02, S-171 76 Stockholm, Sweden. Gary.Cohen@kbh.ki.se
Gary
G
Cohen
Silvano
S
Vella
Heather
H
Jeffery
Hugo
H
Lagercrantz
Miriam
M
Katz-Salamon
D001341:Autonomic Nervous System / Q000254:growth & development / Q000502:physiology; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development / Q000502:physiology*; D011247:Pregnancy; D011249:Pregnancy Complications, Cardiovascular / Q000453:epidemiology / Q000503:physiopathology; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology / Q000503:physiopathology*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology / Q000503:physiopathology*; D013312:Stress, Physiological
D002245:Carbon Dioxide