ObjectiveTo compare and observe the changes in choroidal thickness between healthy pregnant women and healthy non-pregnant women.MethodsA prospective clinical study. From January 2019 to August 2019, healthy pregnant women (pregnant women group) and healthy non-pregnant women age-matched were enrolled during the same period (the normal group) in the obstetrics of Zhuji People's Hospital. All patients were enrolled with their right eyes. Frequency-domain OCT-enhanced depth imaging technology was used to measure the subfoveal macular and 1000 μm above, below, nasal, and temporal choroidal thickness and foveal retinal thickness (CMT). The choroidal thickness and CMT of the pregnant women group and the normal group were compared by t test, and the choroidal thickness and CMT of the normal group and the eyes of different gestational weeks were compared by one-way analysis of variance.ResultsThe pregnant women group and the normal group included 161 patients (161 eyes) and 40 patients (40 eyes). According to the different gestational weeks, the pregnant women were divided into the first trimester group, the second trimester group, and the third trimester group, with 47 patients (47 eyes), 66 patients (66 eyes), and 48 patients (48 eyes) respectively. There was no significant difference in age, axial length, intraocular pressure, and CMT between the different gestational week groups and the normal group (F=1.433, 1.558, 0.416, 2.288; P＞0.05). The subfoveal choroidal thickness (SFCT) of the pregnant women group and normal group were 317.7±73.9 μm and 279.7±44.1 μm, respectively, and the difference was statistically significant (t=3.113, P=0.002). Compared with the normal group, the choroid at the upper, lower, nasal, and temporal sides of the pregnant group 1000 μm from the fovea was thickened. The difference between the upper, nasal and temporal sides was statistically significant (t=2.699, 3.474, 2.595; P＜0.05). The SFCT of the eyes in the first trimester group, the middle group, and the late group were 305.8±72.3, 327.7±69.8, 315.8±80.5 μm, respectively. Compared with the normal group, the difference was statistically significant (F=4.180, P=0.007). Pairwise comparison between the two groups, the second trimester group was significantly different from the normal group (P=0.003). There was no significant difference among the first trimester group、the third trimester group and the other groups (P＞0.05).ConclusionThe choroidal thickness of pregnant women is thicker than normal, and the choroidal thickness in the second trimester reaches the maximum value; while the macular CMT during pregnancy has no significant change.