It’s time to get Scrub’d up! Order now. 

by Dr. Rashmira Balasuriya 


Due to the large surface area that new born babies have, they are quick to be victims of dehydration. It is vital the healthcare practitioners are on the look out for signs of dehydration in babies (dry skin, reduced urine output and lethargy especially) and also correct any feeding difficulties/prescribe adequate maintenance fluid. In the NICU/PBU/SCBU every baby will largely need prescribed IV fluids or feeds unless they are able to be freely given for breast feeding. So here below you’ll find down the rough estimates of fluids to be given for babies and I’ll upload a video on my instagram page showing how to do the calculations.

Fluid calculations

For a baby >1.5 kgs:

  • Day 1 – 60ml/kg/day
  • Day 2 – 75ml/kg/day
  • Day 3 – 90ml/kg/day
  • Day 4 – 105ml/kg/day
  • Day 5 – 120ml/kg/day
  • Day 6 – 135ml/kg/day
  • Day 7 – 150ml/kg/day

So it’s basically a 15ml/kg/day increase daily until day 7, after which the amount of fluid required stays at 150ml/kg/day.

For a baby <1.5kgs – 

  • Day 1 – 80ml/kg/day
  • Day 2 – 95ml/kg/day
  • Day 3 – 110ml/kg/day
  • Day 4 – 125ml/kg/day
  • Day 5 – 140ml/kg/day
  • Day 6 – 155ml/kg/day
  • Day 7 – 170ml/kg/day

For smaller babies the water loss is greater and hence you start at a greater dose of fluids and after day 7 you will target the feeds/fluid to 170ml/kg/day. Not all consultants want an achievement of 170ml/kg/day, most of mine were happy with a day 7 target of 150-160ml/kg/day.

Initially babies on day 1 are most likely to be kept nil by mouth and so fluids are maintained intravenously via a central (umbilical venous catheter) or peripheral line. Babies with respiratory distress or NEC infections may require a delay in feeds and so intravenous fluids take over for longer. For the 1st 48 hours, babies are given only 10% dextrose intravenously. After day 2 is completed, you need to start adding electrolytes which would also be lost by the baby. The required amount for each baby is calculated per the body weight and unlike the IV fluid volume, the amount does not change daily.

  • Na+ (Sodium) – 20ml/kg/day
  • K+ (Potassium) – 1ml/kg/day
  • Ca2+ (Calcium) – 4.4ml/kg/day

Remember that the total amount of electrolytes needs to be deducted from the total IV fluid volume to be given. The rate is calculated by dividing the total IV fluid volume for the day by 24 (per hour).

Once the child is able to start feeds, but cannot yet be given for breastfeeding then tube feeds will be introduced. Cup feeds are given to premature babies who cannot yet breast feed adequately or for mothers with lactation failure. Feeds are calculated again using the daily requirement according to the age of the baby. As an intern in the postnatal wards, adding cup feeds become part and parcel of daily life and so you should get familiar with the fluid requirements for each day. The total maintenance fluid calculation is the same as for the intravenous requirement, you just divide it by 8 instead of 24 as you calculate to give a cup feed every 3 hours.



Here I have written out some examples of how IV fluids are calculated according to the body weight and age of the baby. In this example, the premature neonate weighs 1.3 kilos and is currently 3 days old. After 9:30 a.m. the child has completed 2 days post-birth and has started day 3. With reference to the fluid calculations above, the total IVF required for a day 3 baby weighing less than 1.5kgs is 110 ml/kg/day. The electrolytes also can be added.

Sorry, wordpress charges for video uploads and so if you would like to see the video explanation, please check out my instagram (@scribblingsofamedic).



Vaminolact is an amino acid containing supplement that is given to premature/neonates who are deprived of nutritional feeds due to a variety of reasons such as those who are intubated and ventilated. The amino acids are essential for the development of the body structures and the immune system. Vaminolact is given via a central line (UVC) and is given over 24 hours. The volume required again changes with the age of the baby and the bodyweight (see below).

  • Day 2 – 17ml/kg/day
  • Day 3 – 24ml/kg/day
  • Day 4 – 34ml/kg/day
  • Day 5 – 43ml/kg/day
  • Day 6 – 50ml/kg/day

We commonly use this in our NICU and so I thought I’d add it in here. Again when you give vaminolact, you need to deduct the volume from the total IV fluid volume given for the day.


Prematures are kept in incubators until they achieve a considerable weight (we try to achieve a weight of about 1.4 kgs before trying cot care and then handing over to the mother). Sometimes they reach a plateau weight which is not only frustrating for the healthcare team, but also for the mother who can’t wait to get her hands on her little baby. Studies have found that fortifying human milk will increase the weight and length of the baby.

And that is the jist of fluid maintenance in neonates. I hope this was beneficial and if you have any questions let me know!

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Hi there!

Hi there! Dr. Rashmira Balasuriya is a medical doctor in Sri Lanka, currently training in Family Medicine. Navigating the healthcare system in Sri Lanka is no easy task and this website was created to help guide other foreign medical graduates and junior doctors. This website also helps demystify life as a doctor in Sri Lanka and also combats medical misinformation circulating amongst the general public!