Retinal small vessel narrowing in women with gestational diabetes, pregnancy-associated hypertension, or small-for-gestational age babies.

BACKGROUND: Gestational diabetes, pregnancy-associated hypertension and small-for-gestational age babies are all associated with impaired placental vascularisation. This study compared the effects of these conditions the systemic small vessel calibre that was examined in the retina.

METHODS: This was a cross-sectional observational study of consecutive pregnant women recruited from an antenatal clinic. Participants underwent a Glucose Tolerance Test, BP measurements, and were examined for small-for-gestational age babies as per national guidelines. They also underwent retinal photography with a non-mydriatic camera, and vessel calibres were measured with a validated semi-quantitative system at a retinal grading centre. Some participants also underwent testing of retinal vascular responsiveness to a flickering light.

RESULTS: Women with gestational diabetes ( n  = 68) had a higher mean arterial pressure (85 ± 9 mm Hg) than normal pregnant women ( n  = 27, 80 ± 8 mmHg, p  = 0.01). They also had smaller mean retinal arteriole (147.5 ± 13.6 μm and 159.7 ± 6.7 μm respectively, p  < 0.01) and venular calibre (221.0 ± 13.4 μm and 232.8 ± 20.1 μm respectively, p  < 0.01) than normal. However their babies' mean birth weights were not different from normal (3,311 ± 558 g and 3,401 ± 600 g respectively, p  = 0.48). They also demonstrated a trend to reduced retinal arteriolar dilatation (3.5 ± 1.3%, n  = 23) in response to vasodilatory stimuli (4.4 ± 1.8%) ( n  = 11) ( p  = 0.08) consistent with endothelial dysfunction. Women with pregnancy-associated hypertension ( n  = 35) had a higher mean arterial pressure (101 ± 12 mm Hg, p  < 0.01), a smaller mean retinal arteriolar calibre (139.9 ± 10.6 μm, p  < 0.0001), and a lower baby mean birth weight than for normal pregnancies (3,095 ± 443 g, p  = 0.02). Likewise, women with small-for-gestational age babies ( n  = 31) had a higher mean arterial pressure (89 ± 19 mm Hg, p  = 0.03), a smaller mean retinal arteriolar calibre (141.6 ± 12.8 μm, p  < 0.01) and a lower baby mean birth weight than for normal pregnancies (2,468 ± 324 g, p  < 0.0001).

CONCLUSION: Mean retinal arterial calibre was reduced in women with gestational diabetes, pregnancy-associated hypertension or small-for-gestational age babies. The reduction in calibre was greatest in pregnancy-associated hypertension and small-for-gestational age babies. Systemic arteriole narrowing may contribute to the pathogenesis of placental vascular dysfunction in these conditions.