good first trimester HbA1c ( ≤ 7.0%) compared with 12.9% (9) in those with non-optimal first trimester HbA1c ( > 7.0%) (relative risk 0.49, 95% confidence interval 0.22 to 1.1).
The incidences of major congenital malformations in these two groups were 2.7% (6) and 10.0% (7) (relative risk 0.27, 0.09 to 0.79).