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
- 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
Managing infants at risk commences at birth and continues until discharge. The infant who is able to enterally feed should be fed ideally within the first hour and observations to assess wellbeing should commence. The paediatric team should be informed of the infant’s birth and care to date.
The infant should then be fed again within 3 hours from the initial feed and then continue to feed 3 hourly until blood glucose levels stabilise and are maintained. Prior to the second feed, the midwife must commence blood glucose measurements. These measurements should continue for 48 hours and can be stopped once the infant demonstrates at least two blood glucose levels within the normal range, remains well and continues to feed. The infant’s wellbeing should also be assessed and documentation of results and time of feed recorded in the infant’s notes. It is important to ensure the parents are kept informed throughout.
Infants with persistently low results (less than what has been locally agreed, for example less than 2.6 mmol/L) will require an urgent consultation from the paediatric team and subsequent transfer to the neonatal unit.
Parents should be provided with ongoing feeding support regardless of feeding methods chosen. Breastfeeding mothers may need support with actual feeding or with expressing breastmilk to ensure colostrum is available for the baby. Whether breast or bottle feeding, parents should be taught to recognise behavioural feeding cues or signs of hunger to enable an early response. These include:
- Waking up
- Smacking of lips
- Sucking on a fist
- While feeding, opening mouth.
- Short pitched cry, with clear rises and falls
Infants who are unable to maintain their blood glucose may require admission to a neonatal unit. There they may receive additional feeding support, that is, tube feeding or require an IV bolus of glucose followed by a maintenance infusion of dextrose.
Monitoring of glucose should be done by capillary heel sampling and by means of a quality-assured bedside monitoring device. Low values should be confirmed by the laboratory as plasma glucose results may be higher than blood glucose readings.
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.