Association of small-for-gestational-age status with mortality and morbidity in very preterm Chinese infants.

BACKGROUND: Very preterm infants born small for gestational age (SGA) are at risk for short- and long-term excess mortality and morbidity resulting from immaturity and deficient intrauterine growth. However, previous findings are inconclusive, and there is a paucity of contemporary data in Chinese population. OBJECTIVES: To evaluate the excess risks of mortality and morbidity independently associated with SGA birth in very preterm (before 32 weeks of gestation) Chinese infants. MATERIALS AND METHODS: The study population included all very preterm infants admitted to the neonatal intensive care units (NICUs) in our hospital and our medical treatment partner hospitals during a 6-year period. The SGA group consisted of 615 SGA infants, and 1230 appropriate-for-gestation-age (AGA) infants were matched with GA and sex as controls at a ratio of 2:1. The associations between SGA birth and outcomes (in-hospital mortality and morbidity) were evaluated by using multivariate logistic regression analysis after adjustment for potential confounders. The CRIBII score was used to indicate admission illness severity, acting as a covariate in the multivariate analysis. RESULTS: The SGA group was associated with increased risks of mortality [odds ratio (OR) 2.12; 95% CI: 1.27-3.54] and BPD [OR 1.95; 95% CI: 1.58-2.41] compared to the AGA group. No significant incidences of respiratory distress syndrome (RDS), severe retinopathy of prematurity (sROP), severe intraventricular hemorrhage (sIVH), and necrotizing enterocolitis (NEC) were observed in the SGA group. Further GA-stratified subgroup analysis showed SGA status exhibited certain patterns of effects on mortality and morbidity in different GA ranges. CONCLUSIONS: SGA status is associated with excess risks of neonatal mortality and BPD in very preterm infants, but the increased risks of mortality and morbidity are not homogeneous in different GA ranges. The contemporary data can help inform perinatal care decision-making and family counseling, particularly for very preterm SGA neonates.

Small for gestational age is a risk factor for thyroid dysfunction in preterm newborns.

BACKGROUND: Thyroid hormones play an important role in the normal growth and maturation of the central nervous system. However, few publications addressed the altered thyroid hormone levels in preterm small for gestational age (SGA) newborns. We hypothesized preterm SGA infants have higher thyroid-stimulating hormone (TSH) concentrations than appropriate for gestational age (AGA) ones within the normal range and an increased incidence of thyroid dysfunction. METHODS: The study was designed to compare thyroid hormone levels within the normal range and the incidence of thyroid dysfunction in the SGA and AGA groups to test the hypothesis. The medical records of all preterm infants admitted to the neonatal intensive care unit (NICU) at the First Affiliated Hospital of Shantou University Medical College, Shantou, China, between January 1, 2015 and December 31, 2018, were reviewed. Blood samples were collected between 72 and 96 h of life and analyzed with TSH, free thyroxine (FT4) and free triiodothyronine (FT3) assays. Thyroid function test (TFT) results, and neonatal demographic and clinical factors were analyzed to identify the associations between SGA birth and altered thyroid concentrations and thyroid dysfunction. RESULTS: TSH and FT4 concentrations were significantly higher in the SGA group than the AGA group ((3.74(interquartile range (IQR):2.28 ~ 6.18) vs. 3.01(IQR: 1.81 ~ 5.41) mU/L, p = 0.018), and (17.76 ± 3.94 vs. 17.42 ± 3.71 pmol/L, p = 0.371), respectively). The higher TSH levels were associated with being SGA or Z-score of birth weight (BW) for GA after adjusting for potential confounders ((ßSGA = 0.68 (95% confidence interval (CI) 0.15 ~ 1.21), p = 0.013) or (ßZ-score = - 0.25 (95%CI -0.48 ~ - 0.03), p = 0.028), respectively). However, we did not find a significant association between SGA birth and altered FT4 concentrations. Furthermore, compared with the AGA group, the SGA group presented an increased incidence of transient hypothyroxinemia with delayed TSH elevation (dTSHe), a higher percentage receiving levothyroxine (L-T4) therapy, and a higher rate of follow-up within the first 6 months of life. CONCLUSIONS: Preterm SGA newborns had significantly higher TSH concentrations within the normal range and an increased incidence of thyroid dysfunction. The SGA newborns with these features should be closely followed up with periodical TFTs and endocrinologic evaluation.