Pituitary volume changes in pregnancy and the post-partum period

Imaging changes in the pituitary volume during pregnancy remains scantly researched. This study set out to assess the differences in total, anterior, and posterior pituitary volume in pregnant women compared to nulliparous and post-partum women.

A retrospective review was completed of women that had undergone MRI imaging of the brain. Patients were divided into three cohorts: pregnant, nulliparous, and post-partum (defined as being within 12 months of delivery). Anterior and posterior pituitary volumes were manually measured.

171 patients were included, of which 68 were pregnant, 52 were post-partum, and 51 were nulliparous. The average anterior (621.0 ± 171.6 mm³) and total (705.4 ± 172.2 mm³) pituitary volumes were significantly larger in pregnant patients than nulliparous women (522.6 ± 159.8 mm³ and 624.5 ± 163.7 mm³, respectively) (p = .002 and p = .01, respectively). The posterior pituitary volume was significantly smaller in pregnant women (84.4 ± 32.9 mm³) compared to both post-partum (101.2 ± 42.0 mm³) and nulliparous (102.0 ± 46.1 mm³) women (p = .02 for both).

The anterior and total pituitary volumes are significantly larger during pregnancy persisting into the post-partum period. The posterior pituitary volume, conversely, decreases during pregnancy, and returns to its normal size in the post-partum period.