Yolk sac diameter in early pregnancy in maternal diabetes mellitus.

AIMS: To investigate the possible association between maternal diabetes mellitus and increased yolk sac diameter (YSD). METHODS: We searched the Early Pregnancy Unit database to identify singleton pregnancies with measurements of embryonic crown-rump length (CRL) and YSD at 6-10 weeks of gestation and subsequent delivery of phenotypically normal neonates. We compared the YSD in patients with pre-gestational and gestational diabetes with those who were unaffected by diabetes. RESULTS: A total of 3,686 cases were identified including 43 (1.2%) with type 1 diabetes, 31 (0.8%) with type 2 diabetes and 71 (1.9%) who subsequently developed gestational diabetes. The measured YSD in both the diabetic and non-diabetic groups were expressed as differences from the expected normal mean for CRL (Δ values). There were no significant differences in ΔYSD between the groups. The median (IQR) ΔYSD was 0.01 (-0.33 to 0.37) mm in the unaffected group, 0.01 (-0.35 to 0.51) mm in type 1 diabetes, -0.02 (-3.44 to 0.27) mm in type 2 diabetes and 0.01 (-0.28 to 0.35) mm in gestational diabetes. CONCLUSION: After exclusion of miscarriages and embryopathies, pre-gestational and gestational diabetes are not associated with altered YSD.