Many pregnancies are unexpected. We therefore assessed the impact of an early pregnancy HbA1c above or below non-pregnant targets on perinatal outcomes and HbA1c trajectories throughout pregnancy and 12 months postpartum among individuals with type 2 diabetes (T2D).

We conducted a retrospective cohort study of pregnant individuals with T2D. Outcomes and HbA1c trajectories were compared among those who had an HbA1c <7 versus ≥7% at <20 weeks' gestation. Data were analyzed using logistic regression for perinatal outcomes and linear mixed models to assess trajectories of HbA1c during pregnancy and the postpartum period.

HbA1c was <7% in 128/281 (46%) and ≥7% in 153/281 (54%) individuals. HbA1c ≥7% was associated with risk for preterm birth (adjusted odds ratio [aOR] = 2.3, 95% confidence interval [CI]: 1.3–4.0), cesarean delivery (aOR = 1.7, 95% CI: 1.1–2.9), and neonatal intensive care admission (aOR = 2.9, 95% CI: 1.7–4.9). HbA1c values decreased during pregnancy in both groups but returned to early pregnancy values by the postpartum period.

Adverse perinatal outcomes are high among individuals with type 2 diabetes mellitus regardless of early pregnancy glucose levels, and strategies are needed to improve maternal glucose levels in the postpartum period.

HbA1c ≥7% in early pregnancy increases risk for pregnancy complications.

Pregnancy complication rates in T2D are high even with HbA1c <7%.

In T2D, HbA1c levels improve throughout gestation.

These improvements do not persist 1-year postpartum.

Received: 10 June 2025

Accepted: 13 August 2025

Accepted Manuscript online:
14 August 2025

Article published online:
29 August 2025

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