Fetal Cardiac Structure and Function in Diabetic Pregnancies Within Recommended Glycemic Targets: A Systematic Review...

To systematically evaluate fetal echocardiographic parameters in diabetic pregnancies meeting guideline-recommended HbA1c targets (< 6.5%) and explore variations across glycemic strata.

Seven databases were searched from inception through November 2025.

Observational studies comparing fetal echocardiograms between diabetic pregnancies (mean maternal HbA1c < 6.5%) and healthy controls.

Quality was assessed using Newcastle-Ottawa Scale and JBI checklists; evidence certainty was graded using GRADE. Random-effects models pooled mean differences (MD) and standardized mean differences (SMD).

Twenty studies (2,690 participants; 70% East Asian) were included. In the third trimester, fetuses of diabetic mothers with HbA1c < 6.5% exhibited subtle cardiac alterations: increased interventricular septal thickness (MD, 0.67 mm [95% CI, 0.31 to 1.03 mm], P < .001; 95% PI, -0.58 to 1.92 mm), decreased mitral valve E/A ratio (MD, -0.07 [95% CI, -0.12 to -0.02], P = .01; 95% PI, -0.25 to 0.11), and elevated left ventricular myocardial performance index (MD, 0.08 [95% CI, 0.05 to 0.12], P < .001; 95% PI, -0.04 to 0.20). In exploratory subgroup analyses, differences were attenuated in cohorts reporting mean HbA1c ≤ 5.5%. Univariate meta-regression identified maternal age as an exploratory moderator for mitral valve E/A ratio (P = .0016).

Diabetic pregnancies meeting target HbA1c (< 6.5%) exhibit subtle fetal cardiac differences, which attenuate at ≤ 5.5%. However, very low-certainty evidence, wide prediction intervals crossing null, and residual confounding limit generalizability to higher-BMI or diverse populations, warranting rigorously adjusted prospective cohorts.