Pregnancy-Induced Changes in Ocular Biomechanics Are Related to Maternal Hormone Levels in Healthy Chinese Pregnant Women

Background: To explore the changes in ocular biomechanics during pregnancy and the postpartum period and their association with maternal hormone level changes. Methods: In a prospective cohort study, 24 eyes of 12 pregnant women were enrolled and monitored throughout pregnancy and after delivery (6 weeks). Intraocular pressure (IOP), central corneal thickness (CCT), corneal endothelium cell (CEC), axial length (AL), corneal curvature (K1, K2), anterior chamber depth (ACD), central subfield thickness (CST), macular volume (MV), cube average thickness (CAT), retinal nerve fibre layer (RNFL), tear meniscus height (TMH), and breaking up time (BUT) were measured throughout pregnancy, and blood plasma levels of maternal hormones were determined at the same time points. Results: A gradual decrease in IOP values was observed as gestation progressed, and there was a statistically significant difference in IOP between the 3rd trimester and the 1st and 2nd trimester and postpartum (p = 0.002, p = 0.006, p = 0.050). There was a significant difference between the 1st and 2nd trimesters in terms of MV (p = 0.023). The difference in RNFL in the 3rd trimester and postpartum was significant (p = 0.011). The levels of the β-hCG showed a significant correlation with K2, ACD, and TMH only in the 2nd trimester (r = 0.588, p = 0.045; r = - 0.740, p = 0.006; r = 0.642, p = 0.024). Regarding luteinizing hormone, there was a negative correlation with MV in the 1st and 2nd trimesters (r = - 0.598, p = 0.040; r = - 0.672, p = 0.017) and CAT in the 1st and 2nd trimesters (r = - 0.599, p = 0.040; r = - 0.655, p = 0.021). Luteinizing hormone levels were correlated with ACD (r = - 0.702, p = 0.011) in the 2nd trimester and K2 (r = 0.585, p = 0.046) in the 3rd trimester. A correlation was found between follicle-stimulating hormone levels and CEC, MV and CAT in the 1st trimester (r = - 0.677, p = 0.016; r = - 0.602, p = 0.039; r = - 0.584, p = 0.046) and AL in the 3rd trimester (r = - 0.618, p = 0.032). The correlation between oestradiol and CST in the 1st trimester (r = - 0.621, p = 0.031) and RNFL (r = 0.594, p = 0.041) in the postpartum. A statistically significant correlation between progesterone and MV (r = 0.583, p = 0.047) and TMH (r = 0.762, p = 0.004) was observed in the 1st trimester. No significant intergroup correlation was observed postpartum (p > 0.05). Conclusion: Ophthalmological parameters showed physiological changes induced by hormone levels in pregnancy and returned to baseline levels after delivery.