Early Human Development, 28 (1992) 19-25 Elsevier Scientific Publishers Ireland Ltd. 19 EHD 01213 Transient neonatal hyperthyrotropinaemia Terence T. Laoa, Chi Yin Li” and Nirmal S. Panesarb ODepartment of Obstetrics and Gynaecology and bDepartment of Chemical Pathology, Prince of W ales Hospital, Shatin zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHG (Hong Kong) (Received 15 May 1991; revision received 2 November 1991; accepted 5 November 1991) Summary Of 48 consecutive newborns with elevated umbilical venous plasma thyrotropin (TSH) concentration, only two (4%) were subsequently proved to have congenital hypothyroidism, while the other 46 had transient elevation of TSH. Compared with matched controls, these 46 newborns were all delivered vaginally (P < 0.0003) and had a longer second stage of labour (P < 0.002), together with higher incidences of nuchal encirclement of the cord (P < 0.05) as well as female babies (P < 0.05). There was no difference in the incidence of antenatal complications, mean gesta- tional age, birth weight, or birth asphyxia. There were no small-for-gestational age infants in the study group, while four were found in the controls. The results indicate that elevated umbilical cord plasma TSH concentration may represent a response to the stress of difficult or complicated delivery in the healthy appropriate- or large-for- gestational age newborn who does not have congenital hypothyroidism. Key words: thyrotropin; enthyroid neonates; parturition Introduction The measurement of umbilical cord plasma thyrotropin (TSH) concentration is one of the established screening tests for congenital hypothyroidism [ 11. Occasional cases of unexplained elevated TSH concentration have been found in neonates subsequently shown to be not hypothyroid [I ,2]. However, the underlying cause for this phenomenon is uncertain. The results of our earlier study [3] and that of Fukuda (1987) [4] suggest an association between umbilical cord plasma TSH concentration Correspondence to: T.T. Lao, Perinatal Unit, Suite 775, Mount Sinai Hospital, 600 University Avenue, Toronto, Ont. MSG 1X5, Canada. 0378-3782/92/$05.00 0 1992 Ekevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland