The height of the pituitary in preterm infants during the first 2 years of life: an MRI study.

Pituitary secretory activity is different in premature and full-term infants. The height of the pituitary is a marker of its secretory activity. Our purpose was to use MRI to measure height of the pituitary of premature infants and to compare it with full-term controls. The height was measured on a midline sagittal T1-weighted image in 86 premature infants (gestational age 26-36.9 weeks, mean 32.3+/-2.85 weeks, corrected age 0.33-2 years, mean 0.76+/-0.42 years) and in 70 age- and sex-matched full-term controls. The children were was divided into four age groups: A: > or =0.5 years; B: 0.51-1.0 year; C: 1.01-1.5 years; and D: 1.51-2.00 years. The gland was significantly (P<0.01) higher in the preterm infants than in the controls (3.88+/-0.61 vs 3.31+/-0.64 mm). In the preterm group no significant difference was found between children small or appropriate for gestational age or between those with and without periventricular leukomalacia. Pituitary height by age group was: A: 3.71+/-0.57, B: 3.81+/-0.56, C: 4.09+/-0.68; and D:4.45+/-0.57 mm; statistically significant (P<0.01) differences were found between groups A and D and B and D. The pituitary is thus higher in premature than in full-term controls and shows a trend to increase after the first year of corrected-age life.