Umbilical cord thiocyanate and thyroid function in intrauterine growth-restricted infants of the smoking gravida.
OBJECTIVE
We evaluated maternal and umbilical cord thiocyanate and thyroid function in intrauterine growth-restricted infants of smoking mothers.


METHODS
One hundred six mother-infant pairs were studied and divided into four groups: smokers with appropriate for gestational age infants (n = 37), smokers with intrauterine growth-restricted infants (n = 19), nonsmokers with appropriate for gestational age infants (n = 33), and nonsmokers with intrauterine growth-restricted infants (n = 17). Sera from mothers were analyzed for thiocyanate levels. Serum from umbilical cord blood was analyzed for thiocyanate, thyroxine, resin triiodothyronine uptake, and thyroid-stimulating hormone. The free thyroxine index was then calculated.


RESULTS
A significant correlation was found between maternal and umbilical cord thiocyanate levels (r = 0.90, p < 0.0001). Maternal and umbilical cord thiocyanate concentrations correlated with increased maternal cigarette use. For appropriate for gestational age and intrauterine growth-restricted infants, mean maternal and umbilical cord thiocyanate levels were not significantly different. The umbilical cord thiocyanate level did not correlate with thyroid function or birth weight. The umbilical cord thyroxine level was lower in nonsmokers than in smokers.


CONCLUSIONS
Thiocyanate was not more concentrated in the intrauterine growth-restricted infant and did not correlate with thyroid function or birth weight. The thyroxine level was decreased significantly in intrauterine growth-restricted infants born to nonsmoking mothers. Further studies are necessary to evaluate the effects of smoking on thyroid function and on fetal growth and development.
McMahon
M J
MJ
Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, USA.
Brown
H L
HL
Dean
R A
RA
D016022:Case-Control Studies; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D005317:Fetal Growth Retardation / Q000097:blood / Q000503:physiopathology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011247:Pregnancy; D012907:Smoking / Q000009:adverse effects*; D013861:Thiocyanates / Q000097:blood*; D013961:Thyroid Gland / Q000503:physiopathology*; D013963:Thyroid Hormones / Q000097:blood
D013861:Thiocyanates; D013963:Thyroid Hormones; C031760:thiocyanate