Effects of growth-discordant twin pregnancies on thyroid function of neonates / 中华围产医学杂志

ABSTRACT

Objective To investigate the effects of growth-discordant twin pregnancies on neonatal thyroid stimulating hormone (TSH) level and congenital hypothyroidism (CH).Methods A total of 3 444 live-birth twin neonates born between January 1,2012 and December 30,2014 in Ningbo City were enrolled.Blood samples via heel puncture were collected and tested.Incidence of CH in singleton and twin neonates was compared.Deviation of birth weight larger than 25％ in twin neonates was set as the criteria for discordant growth.TSH and 17 α-hydroxylase levels in CH twins and normal twins,with or without discordant growth,were compared.Chi-square and non-parametric statistics were performed for data analysis.Results The incidence of CH in twin neonates was 0.56％ (19/3 444),higher than that in singleton neonates [0.09％ (203/225 712),x2=76.225,P＜0.01].Among nineteen CH twins,CH occurred in both twins in eight cases (four twins) and in one of the twins in eleven cases.The gestational age at birth in the eight CH twins were less than 37 weeks,with four males and four females;five were low birth weight infants;one twin were dichorionic,and three twins were monochorionic.In the eleven cases of CH occurring in one of the twins,the gestational age was less than 37 weeks in nine cases,eight were low birth weight infants,six were male and five female;seven were monochorionic and four were dichoronic twins.Five cases of temporary hypothyroidism were all low birth weight infants among the growth-discordant twins.CH cases in growth-discordant group had lower birth weight than their normal twins [M(P25-P75),2 100 (1 800-2 600) vs 2 770 (2 530-2 960) g,Z=4.369],and a higher TSH level [15.4 (11.8-18.5) vs 6.4 (4.8-7.9) mU/L,Z=6.339] (both P＜0.05).In normal twins with or without discordant growth,the neonates with a lower birth weight had a higher TSH level [3.6(2.5-4.7) vs 2.4(1.8-2.9) mU/L,Z=0.962] in weight consistent group,compared with 6.0(4.4-7.8) vs 3.4(1.9-4.1) mU/L in weight inconsistent group (Z=4.369),both P＜0.05.Conclusions In the growth-discordant twins,neonates with a lower birth weight have a higher TSH level and a higher risk of temporary hypothyroidism.