Objective To explore the influence of transient hypothyroxinemia of premature (THOP) on their physical and neurological development.
Methods A retrospective medical records review of preterm infants with gestational ages (GA) < 34 weeks who were admitted to Jiangxi Provincial Maternal and Child Health Hospital and underwent initial thyroid function tests within 4 weeks postnatal were recruited as study subjects from May 2019 to September 2021. Their clinical information was collected. They were divided into THOP group and control group based on their thyroid function. Physical and neurological development were compared between 2 groups. Z score was used to evaluate physical developement. Neonatal behavioral neurological assessment (NBNA) (corrected age 0 − 28 days, score > 35 is normal), DST (developmental screening test for child under six), and Gesell developmental test scale were used to evaluate neurological development. Development quotient (DQ) ≥ 85 was normal for DST and Gesell test.
Results Seventy-four in THOP group and 75 in control group finished followed up more than twice within the corrected age of 15 months. THOP group had significantly lower gestational age and birth weight compared with control group (29.2 ± 3.0 weeks vs. 31.1 ± 1.6 weeks, 1 259 ± 292 g vs. 1 511 ± 285 g, all P < 0.001). The length for age Z-score of THOP group was lower than that of control group within corrected age of 8 months, but there was no significant difference in physical development between 2 groups at corrected age of 9 − 15 months (P > 0.05). Two cases were found NBNA score (34 and 35) abnormal in THOP group within 28 days, but NBNA score were all > 35 in control group. The percentage of abnormal DQ in THOP group was higher than that in control group（36.6% vs. 14.3%）at corrected age of 3 − 8 months, but there was no significant difference between 2 groups at 9 − 15 months of corrected age (P > 0.05).
Conclusion THOP has no significant effect on physical and neurological development in preterm infants at the age of 9 − 15 months. THOP might not be the main cause that affecting physical and neurological development of preterm infants.
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