Severity and treatment of diabetic retinopathy before pregnancy, type of diabetes and blood pressure control are all significant factors affecting the progression and development of severe ocular complications in pregnancy. Photo: Getty Images.

Diabetes, quickly becoming a global health problem with its prevalence rising, can cause complications in the eye, such as diabetic retinopathy (DR) and diabetic macular edema (DME). Pregnant women are more vulnerable to these complications, but few studies have been conducted. A new study aimed to analyze risk factors and clinical variables affecting the progression of DR, DME and visual acuity (VA) changes in pregnant patients.

A total of 50 pregnant women with type 1 or 2 diabetes that delivered between January 2010 and December 2022 were included and split into progression and non-progression groups for each of the three primary outcomes: development/progression of DR, development/progression of DME and worsening of VA.

Many risk factors of DR progression in pregnancy were found. Type of diabetes, level of HbA1c at beginning of pregnancy, gestational age, hypertension treatment pre-pregnancy, blood pressure post-pregnancy and intravitreal injections during pregnancy were all significantly different between the progression and no progression groups.

The DR progression group had significantly higher pre-pregnancy HbA1c levels (averaging 9.9±1.9) compared to the no progression group. They also had higher rates (51.9%) of full-term births. The DME progression group had significantly higher rates of type 2 diabetes (100%) compared to the no progression group. Hypertension treatment before pregnancy (81.8%) was also more common in the DME progression group. Intravitreal injections were more common in patients with visual acuity deterioration, and the average number of fetal complications was significantly higher in the VA non-worsening group compared to the progression group.

Type 1 patients were majority Caucasians while the type 2 group was mostly African-American. Previous studies have shown that certain ethnic groups can be at higher risk for DR and DME; African-Americans, Hispanics and South Asians have all been shown to have higher rates of DR than Caucasian populations.

The type 2 group had a much higher pre-pregnancy BMI, falling into the obesity category, which is a well-known as a risk factor for the development of type 2 diabetes. Blood pressure was significantly different between the two groups; many more of the type 2 diabetes patients had hypertension at the end of pregnancy compared to type 1.

Gestational age was statistically significantly different in progression and non-progression groups. Only 21.7% of non-progressors had a full-term pregnancy while 51.9% of patients in the progression group had a full-term pregnancy.

Pre-pregnancy BMI of the mothers was higher in the DR, DME and VA progression groups when compared to their no progression groups, though it was not statistically significant.

HbA1c level at the beginning of pregnancy was significantly different between the DR development/progression and no progression groups, “giving further evidence to the importance of HbA1c control pre-pregnancy,” the authors noted in their paper on the study.

Additionally, more patients that had received hypertension treatment before pregnancy had development/progression of DME. “The percentage of patients that had hypertension at the end of pregnancy that developed/progressed in DME was significantly higher than the percentage of patients that were within normal blood pressure ranges,” the authors explained.

“These findings might help establishing new standard of care for pregnant patients with diabetes, including recommending thorough counseling and screenings before initiating pregnancy and encouraging close follow-up by their entire care team through their pregnancy and after,” the authors concluded.

Rathinavelu J, Sarvepalli SM, Bailey B, et al. The impact of pregnancy on diabetic retinopathy: a single-center study of clinical risk factors. Ophthalmic Res. August 11, 2023. [Epub ahead of print.]