Smaller fetal thymuses in pre‐eclampsia: a prospective cross‐sectional study

OBJECTIVE: To determine whether the thymus is smaller in fetuses of pre-eclamptic mothers than in those of normal controls. METHODS: This was a cross-sectional, prospective, comparative study of sonographically determined fetal thymus measurements in 39 pregnancies with pre-eclampsia and 70 healthy pregnancies. RESULTS: Both the diameter and the perimeter of the fetal thymus were smaller in pregnancies with pre-eclampsia than in healthy controls. The means of the thymus diameters were 28.6 ± 5.9 and 32.9 ± 4.5 mm and of thymus perimeters 80.9 ± 16.5 and 93.1 ± 16.6 mm for pre-eclamptic and healthy pregnancies, respectively (P < 0.001). General linear models showed that smaller fetal thymuses in pre-eclampsia were independent of gestational age, estimated fetal weight, small for gestational age status and antenatal steroid use. CONCLUSIONS: Pre-eclampsia is associated with smaller fetal thymuses.