Evaluation of factors influencing stable microbubble test results in preterm neonates at 30–33 gestational weeks

Oxana A Teslova^1,2, Takehiko Hiroma¹, Elena I Baranovskaya², Tomohiko Nakamura<sup>1

1</sup>Division of Neonatology, Nagano Children's Hospital, Azumino City, Nagano, Japan; ²Department of Obstetrics and Gynecology, Gomel State Medical University, Belarus

Background: The stable microbubble test (SMT) is a sensitive and specific means of predicting respiratory distress syndrome in newborns, using quantitative correlations with concentrations of the protein and lipid components of surfactant. We hypothesized that fetal nutrition would affect the synthesis of surfactant components. The objectives of this study were to evaluate aspects of fetal and maternal nutrition influencing SMT results and related to development of respiratory distress syndrome in preterm neonates.
Methods: Data from 194 preterm neonates of gestational age 23–36 weeks were analyzed using multivariate regression modeling to identify factors influencing SMT results. After adjusting for gestational age, we compared obstetric, maternal, neonatal, and placental data using analysis of variance in 99 neonates at 30–33 weeks of gestation based on results of the SMT. Receiver-operating-characteristic analysis was performed to characterize factors predictive of respiratory distress syndrome.
Results: SMT results were most strongly associated with the concentration of protein in neonatal blood (P < 0.05) and maternal weight gain during pregnancy (P < 0.05). Cutoff values for predicting respiratory distress syndrome were serum protein <4.7 g/L and maternal weight gain <200 g/week.
Conclusion: Inadequate maternal weight gain during pregnancy may play a significant role in immaturity of the surfactant system in the lungs and may be a predictor of respiratory distress syndrome in premature babies.

Keywords: stable microbubble test, respiratory distress syndrome, protein concentration, gestational weight gain