White's classification and pregnancy outcome in women with type 1 diabetes: a population-based cohort study

Our aim was to examine the association of White's classification with obstetric and perinatal risk factors and outcomes in type 1 diabetic patients.

Obstetric records of a population-based cohort of 1,094 consecutive type 1 diabetic patients with a singleton childbirth during 1988-2011 were studied. The most recent childbirth of each woman was included.

The prepregnancy and the first trimester HbA1c increased from White's class B to F (p for trend <0.001). Systolic and diastolic blood pressure and pre-eclampsia frequencies increased stepwise from class B to F (p for trends <0.001). Vaginal deliveries decreased and Caesarean sections and deliveries before 37 weeks increased from class B to F (p for trends <0.001). Fetal macrosomia (p for trend=0.003) decreased and small-for-gestational age infants (p for trend=0.002) and neonatal intensive care unit admissions (p for trend=0.001) increased from class B to F. In logistic regression analysis, White's classes were associated with pre-eclampsia but, with the exception of class R (proliferative retinopathy) and F (nephropathy), not with other adverse outcomes when adjusted for first trimester HbA1c ≥7% (≥53 mmol/mol) and blood pressure ≥140/90 mmHg. First trimester HbA1c ≥7% was associated with pre-eclampsia, preterm delivery, fetal macrosomia and neonatal intensive care unit admission.

White's classification is useful in estimating the risk of pre-eclampsia in early pregnancy independently of suboptimal glycaemic control and hypertension. However, its utility in predicting adverse perinatal outcomes seems limited when information on first trimester HbA1c, blood pressure and diabetic microvascular complications is available.