Heart rate variability in neonates of type 1 diabetic pregnancy

• Neonates of diabetic mothers have decreased HRV with sympathetic predominance.
• This altered HRV is related to fetal acidaemia and maternal and fetal glycaemia.
• Exposure of the developing heart to maternal glycaemic fluctuation may alter HRV.
• Alterations in HRV in utero may explain the fetal programming in maternal diabetes.

BackgroundCardiomyopathy is a common finding in offspring of pre-gestational type 1 diabetic pregnancy. Echocardiographic and biochemical evidence of fetal cardiac dysfunction have also been reported. Studies suggest that offspring of diabetic mothers (ODM) undergo a fetal programming effect due to the hyperglycaemic intrauterine milieu which increases their risk of cardiovascular morbidity in adult life. Decreased neonatal heart rate variability (HRV) has been described in association with in-utero growth restriction, prematurity, sudden infant death syndrome and congenital heart disease. The effect of in-utero exposure to hyperglycaemia in diabetic pregnancy on neonatal HRV is unknown.AimsOur aim was to determine if neonatal HRV differs between normal and diabetic pregnancy.Study design and subjectsThis was a prospective observational study of 38 patients with pregestational type 1 diabetes and 26 controls. HRV assessment was performed using Powerlab (ADI Instruments Ltd).Outcome measuresHeart rate variability assessment and cord blood sampling for pH and glucose were performed for all neonates. Maternal glycaemic control was assessed via measurement of glycosylated haemoglobin in each trimester in the diabetic cohort.ResultsNeonates of diabetic mothers had evidence of altered heart rate variability, with increased low frequency to high frequency ratio (LF: HF), suggestive of a shift towards sympathetic predominance (p < 0.05). This altered HRV was significantly related to fetal acidaemia, cord blood glucose values and maternal glycaemic control during pregnancy (p < 0.05).ConclusionNeonates of pregestational diabetic pregnancy have altered HRV which is related to maternal hyperglycaemia, fetal acidaemia and fetal glycaemia. Exposure of the developing heart to fluctuations in maternal glycaemia with subsequent alterations in HRV may explain why infants of diabetic mothers are at greater risk of cardiovascular disease in later life.