Height of the cerebellar vermis and gestational age at birth.

OBJECTIVES

The objective of this study was to construct reference ranges of the neonatal cerebellar vermis height with respect to the gestational age at birth.

METHODS

This observational study assessed 434 neonates born at 25-42 weeks' gestation. The neonates were singleton and appropriate in size for gestational age, and did not exhibit any abnormalities or neonatal disease. Gestational age was based on the date of the last menstrual period and confirmed by ultrasound examination performed within the 12(th) week of pregnancy. Sonographic measurements of the height of the cerebellar vermis in the mid-sagittal plane were performed within 24 h of birth by the same neonatal sonographer. Reference ranges (5(th), 50(th) and 95(th) centiles) were estimated by a mean and SD model based on least-squares polynomial regression.

RESULTS

Neonatal sonographic measurements were obtained in all cases. Mean (SD) maternal age was 30.2 (4.3) years. Mean cerebellar vermis height adjusted for gestational age did not differ between males and females, the mean adjusted difference being 0.012 (95% CI, - 0.009 to 0.033) cm. Mean cerebellar vermis height (cm) against gestational age (weeks) was suitably modeled by a linear-cubic polynomial as - 1.784 + 0.137 x GA - 0.000019 x GA(3) (SD = - 0.147 + 0.008 x GA), where GA = gestational age.

CONCLUSIONS

Reference ranges for the height of the cerebellar vermis at birth with respect to gestational age at birth have been constructed in appropriate-for-gestational-age neonates.