Prenatal smoking and alterations in newborn heart rate during transition.
OBJECTIVE
To evaluate the effects of prenatal cigarette smoke exposure on newborn heart rate following the physiologic challenge of birth.


METHODS
Nonexperimental, comparative.


METHODS
A convenience sample of 130 full-term, healthy newborns who were born at a suburban medical center.


METHODS
Cotinine is the major metabolite of nicotine and was measured in venous cord blood. The heart rate was monitored at 1 minute intervals during the first 4 hours of life. Infants were categorized into three groups based on the cotinine level: < 0.05 ng/ml (n = 68), 0.05-6.0 ng/ml (n = 39), and > 6.0 ng/ml (n = 23). These levels corresponded, respectively, to no exposure, passive, and active exposure of the mother to nicotine.


RESULTS
A one-way ANOVA was significant for maximum heart rate, F(2, 127) = 9.26, p = .001; range of heart rate, F(2, 127) = 5.4, p = .006; and variance of heart rate, F(2, 127) = 5.24, p = .007. Post hoc multiple comparisons found that newborns with cotinine levels > 6.0 ng/ml differed significantly from infants with cotinine levels < 0.05 ng/ml and 0.05-6.0 ng/ml in maximum heart rate, range of heart rate, and variance of heart rate.


CONCLUSIONS
These findings suggest that newborns with cotinine levels > 6.0 ng/ml have a limited ability to maximize and vary their heart rate. Cardiac output in the newborn is primarily dependent on heart rate. If unable to maximize cardiac output during times of stress, the newborn is potentially at an increased risk for morbidity and possible mortality.
Sherman
Jan
J
University of California San Francisco, School of Nursing, Department of Family Health Care, USA. janski@aol.com
Young
Anne
A
Sherman
Michael P
MP
Collazo
Carmen
C
Bernert
John T
JT
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D003367:Cotinine / Q000097:blood; D005260:Female; D006339:Heart Rate; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012907:Smoking / Q000009:adverse effects*
D003367:Cotinine