ESPE Abstracts

Aim: To evaluate thyroid function tests and affecting factors in twin and triplet newborns.

Method: 655 newborns from 320 multiple gestations (305 twins/15 triplets) were evaluated retrospectively with respect to thyroid function tests (FT4, TSH). The effects of birth order, birth weight SDS, gestational age, maternal thyroid disease, gestational diabetes, assisted reproduction, dopamine were analysed.

Results: Gestational age was 25.0–37.1 weeks (Mean: 33.0±2.2). 38.6% of pregnancies were resulted from assisted reproduction. 10% of babies were SGA. Mean TSH was 5.3±10.9 μIU/ml and 5.6±7.5 μIU/ml; mean ft4 levels were 1.53±0.37 and 1.49±0.34 ng/dl for the first and second born twins respectively (P:0.35 for TSH; P:0.14 for ft4). The frequency of hypothyroidism was 1.07% (7/655). Only one twin (dizygotic) was concordant for hypothyroidism. SGA (59/549) babies had higher TSH(6.7±5.4 vs 5.3±9.7 μIU/ml; P:0.001). Maternal thyroid disease, gestational diabetes and hypertension were detected in 10.5%, 14.5% and 11.7% of pregnancies. Mean TSH was higher in neonates with maternal thyroid disease (7.5±11.5 vs 5.3±8.8 μIU/ml) but the difference was statistically insignificant. There was no difference in TSH and fT4 values of babies born from pregnancies with assisted reproduction. fT4 was lower in babies with dopamine treatment (1.38±0.4 vs 1.52±0.34 ng/dl; P:0.021). A positive correlation was detected between TSH and dopamine treatment duration. A positive correlation was also present between fT4 and gestational age. fT4 and TSH levels were similar in tiplets and birth order did not affect thyroid function tests.

Conclusion: There is a high frequency of hypothyroidism in twins and triplets Although there are many confounding factors, thyroid function tests do not differ in twins and triplets.