The present study investigated the possible association between elevated maternal glycated haemoglobin levels (HbA1c%) and infants with low birth weight (LBW). This case-control study included 1,142 women admitted to three public hospitals in the northeast region of Brazil. The participants were classified based on their glycaemic levels, using glycated haemoglobin measurement: Group 1 (HbA1c% <5.6%), Group 2 (HbA1c% ≥ 5.6% and <6.5%), Group 3 (HbA1c% ≥ 6.5% and <7.0%) and Group 4 (HbA1c% ≥ 7.0%). The main association was assessed via a logistic regression, considering Group 1 (HbA1c <5.6%) as the reference.