Influence of perinatal factors on thyroid stimulating hormone level in cord blood

Abstract

Background:The aim of the present study was to determine the effect of various perinatal factors on cord blood TSH among newborns in Isfahan, Iran.Materials and Methods:This was a descriptive–analytic cross sectional study which performed in Isfahan Iran. During a period of four months, since February to May 2012 a total number of 440 newborns delivered in Alzahra and Shahid beheshti hospitals were enrolled in the study. For all newborns one mL blood sample from umbilical vein was obtained by one of the project investigators and sent to laboratory for further examinations. Cord blood TSH and birth body weight (BBW), gestational age, history of gestational diabetes mellitus (GDM), apgar at one minute, apgar at five minute, newborn gender and the mother's age were documented. Differences considered statistically significant if P < 0.01.Results:440 newborns enrolled in the study, 221 (50.2%) were male and 219 (49.8%) were female. Among study parameters, method of delivery had statistically significant relation with cord blood TSH (P < 0.001), and other factors such as BBW, gestational age, GDM, apgar at one minute, apgar at five minute, newborn gender and the mother's age didn’t have statistically significant relationship with cord TSH level.Conclusion:In conclusion we deduce that the only factor that can affect cord blood TSH was method of delivery. Infant with vaginal delivery has higher TSH level in cord blood. Other factors that were evaluated in this study didn’t have any statistically significant relationship.

Perinatal factors associated with neonatal thyroid-stimulating hormone in normal newborns

“…We did not find any significant differences in TSH level according to sex, in line with many previous studies 6 8 12 13 15 21 22) . However, a few studies have reported higher TSH levels in boys 7 14) .…”

“…There was no relationship between TSH level and maternal age in our study, in line with most previous studies 6 7 8 12 13) . Only one study has reported a positive relationship between maternal age and TSH level 22) .…”

“…In contrast, Herbstman et al 6) reported that infants with 5 minutes AS<8 had higher TSH levels, but there were no differences in TSH level according to 1 minute AS. Some studies have reported no differences in TSH level according to AS 7 13 15) , as we found. Subjects in this study were healthy normal babies with relatively high AS without birth asphyxia.…”

“…Previous studies have reported that TSH levels in cord blood are higher in infants born through vaginal delivery than in those born through cesarean section 5 6 10 11 12 13) , and higher in those born through vacuum-assisted delivery than in those born through spontaneous vaginal delivery 6 10 14) . Our results support these studies, although we investigated capillary blood TSH, not cord blood TSH, and infants born through cesarean section were excluded.…”

“…TSH level was not related to gestational age in this study. Many previous studies have reported that TSH levels increase with increasing gestational age 5 8 19 21 22) ; however, an inverse relationship has also been reported 23) , another study reported higher TSH levels in preterm than in term babies 6) , and several other studies have reported no difference in TSH levels according to gestational age 10 13 15) .…”