Hypoglycaemia in the newborn occurs when normal metabolic adaptation does not occur in the first few hours after birth. Immediately after birth, newborns experience a transient drop in blood glucose, but this is normal and self-limiting. In utero the fetus consumes glucose in order to grow and concentrate glycogen in the liver. Once born the neonate must produce its own glucose or alternative fuels to supply and meet organ needs (such as the brain) and at the same time adjust to intermittent milk feeding. In order for the infant to maintain metabolic function in the ‘fasting state’, the infant must counter-regulate. The initial counter-regulatory process is glycogenolysis, or the breakdown of glycogen. When the glycogen stores are exhausted the neonate will form glucose from non-carbohydrate substances such as lactate, pyruvate, glycerol and alanine by releasing hormones such as glucagon, catecholamines, growth hormone and cortisol. This process known as gluconeogenesis takes place in the liver and produces ketone bodies. Ketone bodies are an alternative fuel that can be used by the body. As glucose levels in the well term neonate decrease, ketone bodies have been observed to increase. The brain has an enhanced capacity in the term neonate to utilise ketone bodies for metabolic energy. Therefore, monitoring glucose alone in a well neonate, provides an incomplete picture and any action in response to a low glucose alone can lead to inappropriate action.

Midwifery units should have guidelines available to inform practice on the assessment, investigation and management of infants at risk of hypoglycaemia (Table 65.1).

Normal healthy term infants commonly feed infrequently in the first 24–48 hours of life and cope with low glucose levels because they are able to counter-regulate. Therefore infants who do not have risk factors do not require glucose monitoring providing they are assessed as well. These infants at birth should be offered skin-to-skin contact with mother at delivery and should be put to the breast within an hour of birth to promote metabolic adaptation.

However, the infant who does want to feed should be assessed for wellbeing. This assessment should consider the following:

• Infant’s muscle tone
  
• Temperature
  
• Colour/perfusion
  
• Respiration rate
  
• Level of consciousness.

If any concerns are raised by the assessment or the infant is symptomatic of hypoglycaemia, the infant should be urgently referred to the paediatric team. A blood sugar alone is not helpful, but should be a part of the full assessment undertaken by the paediatric team. Active treatment will be required with a blood glucose of less than 2.6 mmol/L. Please note there is no agreement in the literature as to what is a normal blood glucose. WHO defines hypoglycaemia as a blood glucose less than 2.6 mmol/L, while NICE uses 2.0 mmol/L for infants of diabetic mothers. Whatever value is used, WHO/NICE/locally agreed value, it should be communicated and used by all healthcare team members.

The signs of hypoglycaemia, like infection can be subtle and non-specific or absent (Box 65.1). Signs of hypoglycaemia are often neurological as this is a reflection of the brain’s needs for glucose. If any of these signs are observed or reported by parents, the infant should be referred immediately for assessment to the paediatric team.

Managing infants at risk

Care must be taken when performing capillary heel sampling. A precision device appropriate for the size of the baby can avoid complications such as infection, osteomyelitis and bruising. Ensure only the areas shaded on Figure 65.1 are used to prevent these complications. In order to manage pain from heel sampling, consider procedural pain measures such as sucrose, use of a pacifier and skin-to-skin contact with parent.