Retinal capillary blood flow in diabetic and nondiabetic women during pregnancy and postpartum period.

PURPOSE To evaluate the response of retinal capillary circulation to pregnancy in women with diabetes and to correlate microcirculatory changes with progression of retinopathy during pregnancy. METHODS A prospective follow-up study of 32 pregnant women with insulin-dependent diabetes and 11 nondiabetic pregnant women. Perimacular capillary blood flow measured noninvasively by retinal flowmetry in the inferior perimacular retina. Eleven nonpregnant diabetic women served as diabetic control subjects. RESULTS In diabetic women, blood flows, measured by small-box analysis, were 233 +/- 69 (mean +/- SD) arbitrary units (AU) during the first trimester, 248 +/- 55 AU during the third trimester, and 238 +/- 46 AU 3 months postpartum, compared with 204 +/- 32, 195 +/- 22, and 196 +/- 34 AU in nondiabetic pregnant women (P = 0.007 between groups). A difference of the same magnitude was evident between the two groups when the mean of the 50th (P = 0.032), 75th (P = 0.004), and 90th (P = 0.007) percentiles of the individual pixel flow values were used in point-wise analysis. In nonpregnant diabetic women, the small-box mean value was 201 +/- 36, and the mean of the 75th percentile value in point-wise analysis was 316 +/- 49. Blood flow was lower in nonpregnant than in pregnant diabetic women during the third trimester (P = 0.023 and P = 0.012, respectively). CONCLUSIONS Compared with nondiabetic pregnant women, retinal capillary blood flow was higher in diabetic women during pregnancy and after delivery. Together with the hormonal and metabolic changes occurring during pregnancy, hyperdynamic retinal capillary circulation may contribute to the progression of retinopathy in pregnant diabetic women.