Research Article

Former Very Preterm Infants Show Alterations in Thyroid Function at a Preschool Age

Table 1

Perinatal characteristics and characteristics at study visit in former term and very preterm infants.

CharacteristicTerm group
VPI group

Sex, male/female, (%)15 (48)/16 (52)41 (50)/41 (50)
Perinatal characteristics
 Gestational age, median (IQR) [weeks]40 (39; 41)30 (28; 31)
 Birth weight, mean (SD) [grams]3340 (439)1211 (409)
 Birth weight -score, mean (SD)−0.24 (0.78)−0.15 (0.94)
 Small for gestational age at birth, (%)2 (6.9)9 (11.0)
 Large for gestational age at birth, (%)1 (3.2)4 (4.9)
 Maternal educational status,5 (16)/15 (48)/11 (36)0 (0)/47 (57)/35 (43)
 unknown/<12 years/≥12 years, (%)
 Smoking during pregnancy,6 (19)/5 (16)/20 (65)0 (0)/23 (28)/59 (72)
 unknown/yes/no, (%)
Characteristics at study visit
 Age at examination, mean (SD) [years]5.5 (0.7)5.4 (0.3)
 Current BMI, median (IQR) [kg/m2]14.8 (14.0; 15.5)14.0 (13.6; 14.9)
 Current BMI z-score, mean (SD)−0.38 (0.84)−0.91 (1.31)
 fT3, mean (SD) [pmol/l]6.5 (0.7)6.8 (0.7)
 fT4, mean (SD) [pmol/l]17.0 (2.1)16.1 (1.8)
 TSH, mean (SD) [µU/ml]2.3 (1.0)3.0 (1.4)

BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); fT3, free triiodothyronine; fT4, free thyroxine; IQR, interquartile range; SD, standard deviation; TSH, thyroid stimulating hormone; VPI, very preterm infant; , term versus VPI group; , term versus VPI group; , term versus VPI group.