Dense sampling for mapping pituitary growth dynamics before, during, and after pregnancy

Area of Science:

• Endocrinology
• Neuroimaging
• Human Physiology

Background:

• Pregnancy involves significant endocrine shifts and brain changes.
• Pituitary gland volume changes during pregnancy are emerging biomarkers for endocrine activity.
• The precise trajectory of pituitary volume changes during human pregnancy is not well-documented.

Purpose of the Study:

• To describe the longitudinal trajectory of anterior and posterior pituitary lobe volumes during human pregnancy.
• To investigate the relationship between gestational age and pituitary volume.
• To establish normative data for pituitary gland volume changes across the pregnancy spectrum.

Main Methods:

• Three healthy women underwent serial T1-weighted MRI scans (59 total observations) from preconception through 1 year postpartum.
• Longitudinal image registration and label propagation were used for pituitary lobe delineation.
• Generalized additive mixed models (GAMMs) analyzed nonlinear volume trajectories, with person-centered z-scores and nonlinear analyses.

Main Results:

• The anterior pituitary lobe exhibited a nonlinear volume trajectory, significantly influenced by gestational age (73% of variance explained).
• Volume decreased modestly in the first trimester, then increased substantially by the third trimester (~17.5% increase), returning to baseline postpartum.
• No significant volumetric changes were observed in the posterior pituitary lobe throughout the study period.

Conclusions:

• Rapid, reversible anterior pituitary hypertrophy occurs during human pregnancy, likely reflecting lactotrope expansion and increased endocrine demands.
• These findings provide crucial insights into the dynamic endocrine adaptations of pregnancy.
• The posterior pituitary volume remains stable, suggesting differential regulation between the lobes during gestation.