Cord Blood Thyroid-Stimulating Hormone Level: Interpretation in Light of Antenatal and Perinatal Factors

Abstract

Objective: To study the influence of antenatal and perinatal factors on umbilical cord blood thyroid-stimulating hormone (CB TSH) levels. Design: Cross-sectional study. Setting: Private Medical College. Methods: CB TSH levels were measured in 1147 neonates using chemiluminescence immunoassay. The effect of antenatal and perinatal factors on CB TSH values was analyzed statistically. Results: The mean TSH value was 6.811 mIu/mL. A total of 44 neonates (3.83%) had a CB TSH value greater than 20 mIu/mL and had to be recalled for a repeat workup. CB TSH was significantly raised in first-order births, those born via normal vaginal delivery, and in those whom the lower section caesarean section (LSCS) was done for fetal distress (all P value <.05). Male babies had a significantly higher CB TSH value as compared to the females. Babies having Apgar < 7 at 1 min also had a significantly higher CB TSH value. Maternal hypothyroidism did not have any significant effect. On multivariate analysis, we found a positive correlation between birth weight, Apgar, and gestational age with CB TSH values. Conclusion: The incidence of neonates having a CB TSH greater than 20 mIu/mL was 3.83%. Male children, those delivered via normal delivery, those delivered via LSCS where fetal distress was an indication, and those requiring resuscitation, were significant factors affecting CB TSH values.