What is newborn hypernatraemia?

Difficulty breastfeeding can lead to newborn dehydration, we explain how to spot the signs


The UK’s largest study of women struggling to breastfeed by the NHS reveals a few babies suffer hypernatraemia, a severe form of dehydration, but that severe illness is rare. But new mums are being urged to look out for the warning signs if breastfeeding is initially difficult to establish.


Hypernatraemia explained

Hypernatraemia is a severe form of dehydration, occuring when a baby has been unable to get enough milk, leading to higher levels of salt in the blood. This condition sees babies re-admitted into hospital and can, if untreated, lead to seizures, gangrene, brain damage and in the worst cases, death.

The study, lead by Dr Sam Oddie (a consultant neonatologist at Bradford Royal Infirmary), found that hypernatraemia was most common among babies whose mums had had difficulty breastfeeding.

Dr Oddie says, “Our research shows that this condition is strongly associated with problems in breastmilk transfer when babies fail to take in sufficient quantities of milk in the early days of life.”

The study monitored 92.8% of 880,000 live births and found that 62 of the babies had hypernatraemia. “Only one of the 62 cases had been exclusively formula fed before developing the condition and 52 of the babies were first-borns, so the research shows this illness is intrinsically linked with first-time mums who may not realise their babies are ill,” Dr Oddie continues.

Although frightening when you’re a new mum, especially as you may already feel under pressure to get breastfeeding right straight away, the research shows the likelihood of the condition is 7 per 100,000 per live births – a figure that is lower than previously thought.

Dr Oddie adds, “The positive news is that no babies got seriously ill or died, indicating that the management of diagnosed cases in hospitals is good.”

The Department of Health currently advises all women to exclusively breastfeed for the first six months, to protect both baby and mother from potential future illnesses. However, statistics from the NHS suggest less than 1% of women actually do this.

Researchers believe that hypernatraemia occurs because women are not getting enough help addressing initial problems with positioning and attachment. It’s particularly important to address this early on as all cases of hypernatraemia were found to present in the first three days.

Dr Oddie urges, “As far as I’m concerned the answer isn’t more formula feeding, but better support for breastfeeding from the outset.”

What are the signs?

Signs to look out for include an obvious difficulty in getting your baby to breastfeed, unexplained weight loss and a decreased stool output.

Geraldine Miskin, independent breastfeeding specialist and owner of the Breastfeeding Experience, says, “I’ve heard of some mums being told that if their baby doesn’t poo for the first few days then that’s ok – that’s shocking! What goes in must come out as colostrum has a natural laxative effective to encourage poos and reduce incidence of jaundice. As a new mum you would expect to see poos from day one if your baby is getting colostrum. Ensure that you can recognise swallows either by audible or visual cues.”

While there is no uniform newborn weighing programme, all 62 babies who had hypernatraemia were found to lose weight. However, be careful not to jump to conclusions as your baby’s weight will fluctuate in the first few days (if not weeks).

Geraldine notes, “Induction and instrumental deliveries where mums are given IV fluids can distort baby’s birth weight, as baby takes on some of the IV fluids during labour. It is good practice to have your baby weighed 24 hours after birth for baby’s ‘true’ birth weight once excess fluid has been excreted so that it doesn’t cause unnecessary concern.”

Here Anna Burbidge, chair of the La Leche League council of directors explains how to get your baby to latch on correctly (and how to know if she’s not):

When to start breastfeeding

The good news is that straight after you give birth, your breasts will already be making milk. In fact, your breasts start to produce the early milk – colostrum – during pregnancy.  Your baby will probably be interested in breastfeeding within the very first hour after birth.

Spending time skin-to-skin has been shown to help a baby breastfeed. It helps to trigger your baby’s natural feeding reflexes and prompt her to seek out the breast and latch on effectively.

The first time your newborn baby feeds, she generally only takes in a teaspoon of milk (colostrum).

How often?

Your one-day-old baby only has a stomach the size of a small marble, and takes around 5-7ml per feed. As your newborn baby only has a tiny tummy, she can’t wait long for food. In the early days, expect your newborn to feed at least eight to 12 times in a 24-hour period – around every two hours. These small frequent feeds ensure that your baby gets all the milk she requires.

Let your baby breastfeed for as long and often as she seems interested.

How you can help your baby latch on effectively

  • First get comfortable and relaxed – sit or lie back with your back well supported. Use pillows and cushions if necessary to support your head, shoulders, arms or legs, but avoid using them under your baby.
  • Let your breast lie at its natural level, and make sure you feel comfy. 
  • Bring your baby to your breast, not your breast to your baby. Don’t be tempted to lift your breast and push it into your baby’s mouth.
  • Position your baby with her tummy along or across your body. Keep her head and body in line, with her nose opposite your nipple.
  • Help your baby latch on ‘nose to nipple’, with her ‘chin first’ close to or on the breast, and her head tilted slightly back. As she latches on, her lower jaw will be tucked into your breast, well back from the base of your nipple, with her nose free, so she can take in a really big mouthful of breast tissue.
  • Try pulling your baby’s body in close to you as she attaches.

How do you know if your baby has latched on correctly?

Spending a lot of time at the breast doesn’t automatically mean your baby is getting lots of milk if she isn’t well-attached.

Anna says, “If your baby is making little clicking noises, often it means that your baby is not attached properly, and the nipple isn’t sealed.  The baby may be just nipple sucking, and not getting anything from the surrounding areola, and milk ducts.” Your baby may just be sucking on the nipple instead of taking a big mouthful of breast. A shallow latch like this means it will make it difficult to get enough milk, and she may make you sore.

Signs your baby has attached well and is getting milk include:

  • Swallowing movements – frequent at the start of a feed, and less so towards the end. Also listen out for swallowing sounds.
  • Your baby’s nose and chin are in contact with the breast.
  • Both your baby’s top and bottom lip are protruding outwards.
  • Your baby’s cheeks are full and round – if your baby’s cheeks appear dimpled when she sucks, it may mean there is too much unfilled space in this mouth.
  • Breastfeeding is comfortable for you, with no pain.
  • Your nipple is symmetrical, not misshapen, when it comes out of your baby’s mouth.

How do you know your baby’s getting enough breast milk?

  • A baby who is getting enough milk will look satisfied after a feed, will be gaining weight and producing wet and dirty nappies. It’s common for babies to protest when put down – this is not necessarily a sign they are hungry – rather it’s a sign of attachment and a strong survival instinct.
  • In the first three days after birth, you’ll still see the thick, sticky, black meconium poos. After this stage, your baby should have at least six wet nappies a day, and pass at least two loose yellow stools a day.
  • Newborns often lose up to 7% of their birth weight in the first few days. Once your milk production increases, usually on day 3 or 4, expect your baby to regain weight. Most babies reach their birth weight again by day 10 to 14.
  • If your baby is not gaining weight as quickly as expected (based on growth charts), then you may need to supplement his intake temporarily.  Expressing milk is a good way to both supplement your baby’s feeds and also increase your milk production.

How birth affects breastfeeding

“How birth affects breastfeeding is often overlooked,” says Geraldine. “During labour and delivery your baby’s head is compressed which can affect the cranial nerves’ efficiency at innervating muscles needed for latching, sucking and swallowing – 6 of the 12 are needed for feeding. Your baby is designed to undergo cranial moulding however it is not uncommon to find that breastfeeding difficulties are evident following challenging and assisted births. Breastfeeding is an elegant yet complex sequence of events involving many different aspects. It won’t matter how many times you try and re-position, as that isn’t the crux of the problem. If you are struggling, get individual tailored help from somebody who takes your birth and anatomy into consideration.

I champion the idea of ‘if in doubt feed’, but if you are having difficulty breastfeeding, it may be because of the effect of labour and at this point it’s important to protect your milk supply so that you are able to get baby back onto the breast later on. Hand express droplets of colostrum frequently to encourage more production and keep your baby hydrated, rather than force the breastfeeding issue. This way you can put colostrum on your baby’s lips and tongue to stabilise baby’s blood sugar levels. Keep baby with you, close to you and in skin to skin contact as this encourages baby to try to feed. If baby can’t latch, try using nipple shields so that your baby gets colostrum and doesn’t need supplements.


The World Health Organisation does not recommend using shields as a piece of breastfeeding equipment due to your baby’s muscle memory – in which she learns how to use the oral muscles to suckle and transfer milk – but shields can help give your baby something firm to latch onto in order to better access your colostrum or milk. Similarly, if shields don’t work I’d rather a mum offer small supplements of formula in combination with breastfeeding, than seeing a baby hospitalised with dehydration. Don’t give up on breastfeeding if your baby needs supplements in the early days. With the right help, you can increase your supply to meet baby’s needs, find and resolve the root of your breastfeeding problem, so that you and baby can get back to trouble free breastfeeds later on.” Geraldine adds.

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