Diabetic retinopathy in pregnancy.

Diabetic retinopathy is one of the major causes of preventable blindness in the UK and USA in those aged between 24 and 64 years. For a proportion of diabetic women, the first half of this period coincides with peak fertility and childbearing years. Diabetic eye disease may develop for the first time during pregnancy, and visual loss at this stage has serious implications for both the patient and her family. In the past, the prognosis for pregnancy in diabetic women with microvascular disease was so poor that many physicians advised avoidance or termination of pregnancy. With the recognition that the level of glycaemia during pregnancy is directly related to the incidence of congenital malformations, the emphasis on the management of diabetic pregnancy has been one of meticulous control of blood sugar and this has undoubtedly resulted in lower rates of fetal malformations. However, intensive control of glycaemia may carry risks to diabetic mothers particularly to those with established microvascular diseases such as retinopathy and nephropathy. Studies on the influence of pregnancy on the natural history of diabetic retinopathy have shown that deterioration is frequently observed. 4 Until recently there has been controversy as to whether the progression of retinopathy which occurs in such women is due to the natural tendency of diabetic retinopathy to worsen or to unique factors operative during pregnancy. Several major studies have gone some way towards explaining the mechanisms underlying progression of retinopathy during pregnancy. Klein et al performed a prospective study on a large series of individuals, comprising 171 pregnant and 298 non-pregnant insulin dependent diabetic women. The level of diabetic retinopathy in the first trimester was assessed using standard retinal photographs and compared with postpartum photographs. After adjusting for duration of diabetes, glycaemic control, and blood pressure current pregnancy was found to be a major risk factor for the progression of retinopathy. Similarly, Moloney and Drury, also using retinal photography as a means of assessing retinopathy, found that current pregnancy in 53 pregnant diabetic women was associated both with an increased prevalence (from 62% to 77%) and severity of retinopathy whereas in the control group of 39 non-pregnant diabetic women the prevalence of retinopathy remained unchanged at 46% throughout the study period. That retinopathy worsens during pregnancy is now undisputed, although the mechanism by which progression occurs is not entirely clear.