Dehydration & Jaundice

Dehydration & Weight Loss

by Dr Clare Macdonald, General Practitioner 

Infants require adequate fluid and nutrient intake in order to avoid compromising their normal physiology and growth. Infants are at particular risk of dehydration due to their large surface area in relation to weight, and their complete reliance on caregivers to ensure adequate fluid intake. It can be difficult to distinguish a healthy infant from one at risk of dehydration or jaundice and so routine examinations of the newborn by midwives in the early post-partum period are crucial to identify those babies who require more support or assessment. An additional opportunity for assessment and identification is when mothers and babies attend primary care for the neonatal assessment in the first 72 hours of life, or self-present with concerns.

History and examination to help determine infant wellbeing include:

  • Urine and stool output– should be increasing in frequency and volume throughout week 1
  • Feed frequency– 8 or more/24hours after day 1
  • Signs of successful milk transfer (see our webpage on ‘Positioning and Attachment‘)
  • Infant behaviour– waking for feeds, relaxed, not irritable

NCT: Newborn Baby Poo in Nappies- What to Expect Explains how the contents of the nappy can indicate if a baby is feeding effectively.

Weight is measured in the early neonatal period as a proxy for effective feeding and infant wellbeing. Some weight loss is expected in the early days and is not usually harmful; it generally peaks around day 2-3, with birthweight usually being regained by day 10-14. Normal weight loss in exclusively breastfed infants is typically around 6%1, 2 and around 3.5% in formula fed infants2.

NICE recommend weighing infants soon after the first hour after delivery3.  NICE Guideline NG75 instructs on the level of weight loss that should trigger further assessment and management4. Local guidelines may also exist to assist the management of faltering growth.

NICE Guideline NG75 Faltering Growth: Recognition and Management of Faltering Growth in Children September 2017

Excessive weight loss is generally indicative of suboptimal feeding, and infants with excessive weight loss are potentially dehydrated or at risk of dehydration. Hypernatraemic dehydration is of particular concern and can arise as a result of suboptimal breastfeeding5 or improper preparation of infant formula6. Infants with hypernatraemic dehydration can appear surprisingly well, as the physiological cerebral changes mean that typical signs of dehydration such as sunken eyes or depressed fontanelle may be absent. They can rapidly deteriorate and may present acutely, severely unwell. Ensuring optimal breastfeeding, identifying infants with excessive weight loss early and initiating prompt intervention when necessary is key to reducing rates and severity of hypernatraemic dehydration7.


by Dr Victoria Thomas, Consultant Paediatrician

Jaundice in newborns is common. Approximately 60% of term and 80% of preterm babies develop jaundice in the first week of life8 with physiological and breastmilk jaundice being the most common causes. Although most jaundice in newborn infants is benign, clinicians need to be aware of the potential for significant illness.

Neonatal Jaundice

Red Flags include:

  • Jaundice in the first 24 hours of life– requires urgent (same day) paediatric/neonatal assessment.
  • Jaundice persisting after 14 days of life in a baby born after 37 weeks gestation, or after 21 days in a baby born before 37 weeks– requires referral to paediatrics in the next 24-48 hours.
  • Babies who look unwell as well as being jaundiced– require emergency referral.
  • A bilirubin level of >250 umol/l in a term baby (or lower in a preterm baby) requires further assessment as it may require treatment. Very high levels (typically >500umol/L in a term baby) can cause kernicterus and brain injury.
  • Pale (cream or white) stools and dark urine– these raise concern over the possibility of conjugated hyperbilirubinaemia, which is always pathological and requires paediatric referral.

Physiological Jaundice

This is due to the breakdown of the relative excess of red blood cells after birth, combined with a relatively low activity level of UDP-glucoronyltransferase, the enzyme which clears bilirubin. Babies who only have physiological jaundice will be very well. The jaundice peaks on day 3-4 of life and resolves spontaneously, although phototherapy is used if the bilirubin is high. Sometimes families are told to put the baby near a window but this is not evidence based and usually only exposes the baby to a draught.

Jaundice in a Breastfed Infant

Breast fed infants may develop:

  • Physiological jaundice– described above
  • Jaundice associated with suboptimal breast feeding– this is classically associated with weight loss >10% and a viscious cycle of sleepiness that in turn leads to further poor feeding. Significant weight loss and/or a very sleepy baby requires paediatric assessment. All cases require assessment by an experienced breastfeeding support health professional9, and a minority require supplemental feeds and hospital admission. Severe cases are also associated with hypernatraemia.
  • ‘Breastmilk associated jaundice’ is poorly understood but may result in prolonged jaundice in an otherwise well infant. It is probably due to the presence of substances in breastmilk such as beta-glucoronidases and non-esterified fatty acids which impede normal bile metabolism. It is not a reason to stop breastfeeding and once baseline investigations have been performed and pathological causes ruled out, (referral as above) the family can be reassured.

Pathological Causes of Jaundice

These are legion and a full list is beyond the scope of this article. Hamolysis, infection (including congenital infection), congenital anomalies, syndromes and endocrine and metabolic disorders are among the culprits. Investigation is guided by the type of jaundice presentation, the condition of the baby, the history (including birth, past medical history, family and social history, consanguinity, the ethnic origin of the family etc). Prompt recognition and investigation of jaundice is significant however as biliary atresia in particular requires early identification to optimise prognosis– delayed presentation may mean that surgical intervention with a Kasai procedure is not feasible and the only treatment option is liver transplant.

Phototherapy for Neonatal Jaundice

NICE Guidelines CG98: Jaundice in Newborn Babies Under 28 days Updated October 2016

NICE CKS: Jaundice in the Newborn November 2015

Academy of Breastfeeding Medicine: Clinical Protocol #22- Guidelines for Management of Jaundice in the Breastfeeding Infant 35 Weeks or More of Gestation Revised 2017

The NHS Website: Newborn Jaundice Information for parents

With thanks to Dr Thomas for her contribution to this website. Her article A Breastfeeding Paediatrician by Victoria Thomas, Medical Woman (Autumn 2014) highlights important issues for physicians supporting breastfeeding women.

Thanks also to Dr Nick Embleton, Consultant Neonatologist at the Royal Victoria Infirmary (RVI), Newcastle upon Tyne, for his editorial support. 


  1. Noel-Weiss J, Courant G, Woodend AK. Physiological weight loss in the breastfed neonate: a systematic review. Open Medicine. 2008;2(4):e99-e110.
  2. Macdonald P, Ross S, Grant L, Young D. Neonatal weight loss in breast and formula fed infants. Archives of Disease in Childhood Fetal and Neonatal Edition. 2003 Nov;88(6):F472-6.
  3. NICE Guidelines CG190: Intrapartum Care for Healthy Women and Babies Updated November 2016
  4. NICE Guideline NG75 Faltering Growth: Recognition and Management of Faltering Growth in Children September 2017
  5. Oddie S. Hypernatraemic dehydration and breast feeding: a population study. Archives of Disease in Childhood. 2001;85(4):318-320.
  6. Laing I. Hypernatraemia in the first few days: is the incidence rising?. Archives of Disease in Childhood – Fetal and Neonatal Edition. 2002;87(3):158F-162.
  7. Iyer N, Srinivasan R, Evans K, Ward L, Cheung W, Matthes J. Impact of an early weighing policy on neonatal hypernatraemic dehydration and breast feeding. Archives of Disease in Childhood. 2008;93(4):297-299.
  8. NICE Guidelines CG98: Jaundice in Newborn Babies Under 28 days Updated October  2016
  9. Academy of Breastfeeding Medicine: Clinical Protocol #22- Guidelines for Management of Jaundice in the Breastfeeding Infant 35 Weeks or More of Gestation Revised 2017

Published April 2017, Updated October 16th 2019