Developmental Outcomes among Very Low Birth Weight Infants with Normal Cranial Ultrasound Images

Abstract

Objective: Severe abnormalities on cranial ultrasound images are important predictors of cerebral palsy (CP) and mental retardation; on the contrary, normal results on cranial echograms usually favor normal neurological outcomes. With the increased survival rates of very low birth weight (VLBW, birth weight ＜1500 g) premature infants, the prognoses of VLBW preterm infants with normal cranial ultrasound images requires investigation and this is the aim of this study. Methods: From February 1998 through December 2005, all VLBW premature infants who were admitted to the neonatal intensive care unit (NICU) of the Taichung Veterans General Hospital (VGHTC) and survived to discharge with normal cranial ultrasound images were enrolled prospectively. Abnormal developmental outcome was defined as mental development index (MDI) or psychomotor development index (PDI) scores ＜84 on the Bayley Scales of Infant Development-II (BSID II). Risk factors for abnormal developmental outcomes in our study included demographic characteristics of the infants, necrotizing enterocolitis (NEC), chronic lung disease (CLD), patent ductus arteriosus (PDA), infection, duration of ventilation, length of hospitalization and parents' socioeconomic status. Results: Totally, there were 160 cases enrolled and 122 of them (76.3%) returned for follow-up assessment at the corrected age 18-36 months. Forty-eight infants (39.3%) had MDI or PDI＜84. Among the 48 cases, 18 cases (14.7%) had MDI＜69, and nine cases (7.4%) had both MDI and PDI＜69. In logistic regression mode, factors associated with impaired developmental outcomes in our study were male gender (OR:3.97; 95% CI:1.38-11.40), culture-proven sepsis (OR:6.40; 95% CI:1.65-24.92), maternal disease (OR:6.02; 95% CI:1.58-22.87), infertility management (OR:0.26; 95% CI:0.08-0.84), maternal age (OR:0.87; 95% CI:0.76-0.99), and paternal age (OR:1.13; 95% CI:1.00-1.27). Conclusion: Nearly 40% of the VLBW premature infants with normal cranial ultrasound images at discharge had impaired developmental outcomes. The infants with risk factors should be followed carefully.