Response to Cundy Free

We thank Dr. Cundy (1) for his interest in and careful reading of the article of the Diabetes Control and Complications Trial (DCCT) Research Group that focused on the risk for developing progressive retinopathy during and after pregnancy (2). Given the relatively small number of women who became pregnant (n = 180) and the even smaller number of pregnant women who developed severe retinopathy in the DCCT (defined as proliferative or severe nonproliferative retinopathy, n = 13), we were hesitant to make any specific recommendations that could potentially jeopardize patient safety. Moreover, both the frequent follow-up of DCCT volunteers with standardized research-quality stereoscopic fundus photography and the generally low level of mean HbA_1c before pregnancy (7.4 and 8.1% in the intensive and conventional treatment groups, respectively) (3) made translation of our results to the nonresearch population problematic and further tempered our recommendations.

On the other hand, we must ask Dr. Cundy whether the relationship between baseline retinopathy status before pregnancy and the risk of progressive retinopathy during and after pregnancy can help to refine current recommendations regarding the need to screen diabetic women frequently during and after pregnancy. Specifically, did any of the women who developed severe retinopathy during or after pregnancy have no or only minimal retinopathy before pregnancy? With a large enough group of women who became pregnant with no retinopathy at baseline, we should be able to cast some light on whether such patients are at any substantive risk for developing severe retinopathy during and shortly after pregnancy. Furthermore, we should be able to determine the need for frequent ophthalmologic surveillance.

Of 270 pregnancies in the DCCT, 183 were in women who showed no or only minimal retinopathy (microaneurysms only) at the examination immediately preceding the pregnancy. Three (1.6%) developed severe retinopathy. Conversely, of the 13 patients who developed severe retinopathy during their pregnancies, none had no retinopathy, 3 had retinopathy, and 10 had mild to moderately severe nonproliferative retinopathy before their pregnancies. The small number of patients with severe retinopathy associated with pregnancy precludes any detailed analyses or conclusive determinations. However, on the basis that only three cases of severe retinopathy developed during 183 pregnancies that showed no or only minimal retinopathy before pregnancy, we can hypothesize that the risk in such women is quite low.

In summary, the major findings of our study are the following: pregnancy increases the risk for progressive retinopathy during and in the first year after pregnancy; the risk cannot be explained entirely by the transient worsening associated with intensification of therapy, although intensification of therapy did impact the risk (4); and the adverse effects of pregnancy on retinopathy appear to dissipate and generally do not affect long-term outcome. We have previously demonstrated that the degree of baseline retinopathy affects the risk of progressive retinopathy in nonpregnant patients. (5) Similarly, a low level of retinopathy before pregnancy appears to be associated with low risk for developing severe retinopathy during or shortly after pregnancy; however, the relatively small subset of DCCT participants who became pregnant prevents us from concluding that ophthalmologic screening during pregnancy is unnecessary—even in women with little or no retinopathy before their pregnancy.