Maternal and perinatal factors associated with cord blood thyroid-stimulating hormone levels: a cross-sectional study

Purpose: Congenital hypothyroidism (CH) is the most common preventable cause of intellectual disability in children. Umbilical cord blood thyroid-stimulating hormone (TSH) is used for neonatal screening, but maternal and perinatal influences on cord blood TSH remain incompletely understood. This study aimed to identify maternal and perinatal factors associated with cord blood TSH levels.Methods: A descriptive, cross-sectional study was conducted among 1,088 consecutive live births at a tertiary hospital in South India (January–December 2022). Cord blood samples were analyzed for TSH using an electrochemiluminescence immunoassay. Maternal and neonatal characteristics were recorded, and associations with cord blood TSH were assessed. Neonates with cord blood TSH >20 μIU/mL were recalled for confirmatory serum thyroid function testing.Results: The median cord blood TSH was 7.22 μIU/mL, with an interquartile range of 5.39–10.28. Elevated cord blood TSH (>20 μIU/mL) was found in 5.9% of neonates. In unadjusted analyses, higher TSH levels were associated with primiparity, gestational diabetes, gestational hypertension, vaginal delivery, assisted delivery, and lower Apgar scores (P<0.05). Maternal TSH was positively correlated with cord blood TSH (r=0.193, P=0.002). No associations were observed with neonatal sex, gestational age, birth weight, or maternal anemia. Cord blood TSH showed modest positive correlations with postnatal day-3 serum TSH and free thyroxine.Conclusion: Maternal thyroid status, parity, pregnancy complications, and mode of delivery are significantly associated with cord blood TSH. These factors should be considered when interpreting neonatal screening results for CH.