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BASE - looking at the use of sodium bicarbonate for metabolic acidosis in very preterm babies


Metabolic acidosis is a build-up of acid in the bloodstream. In the UK, 8,000 infants are born very preterm each year and many will develop metabolic acidosis during their stay on a neonatal unit.

Sodium bicarbonate is often used when a premature baby has metabolic acidosis. Some doctors believe that giving sodium bicarbonate lowers acid levels in the bloodstream and improves the functioning of the heart, but others believe sodium bicarbonate raises acid levels in the cells of the body which can be harmful in the short and long-term by affecting blood flow to the brain and other tissues in the body.

The two approaches of managing metabolic acidosis with sodium bicarbonate, or not, are already used across the UK, so there is nothing new about either type of care. At the moment we do not know which approach for babies is better because this has never been properly studied.

We want to answer the question:

In very preterm babies with metabolic acidosis, does using sodium bicarbonate or not impact their health and development in the short and long term?

How we will do this?

To answer this question, very preterm babies (born before 31 weeks of gestation) with metabolic acidosis will be put at random into one of two groups:

  • Will be given sodium bicarbonate when they have metabolic acidosis
  • Will not be given sodium bicarbonate when they have metabolic acidosis

We will then compare the two groups to find out whether giving sodium bicarbonate or not affects very preterm babies' health in the short term. Babies will also be followed up until they are 2 years old to understand if there are any longer-term effects of giving sodium bicarbonate or not on development.

The trial will recruit 3,764 infants in approximately 45 neonatal units in the UK over a 3 year recruitment period.

BASE is coordinated by the National Perinatal Epidemiology Unit Clinical Trial Unit (NPEU CTU) at the University of Oxford and is funded by the National Institute of National Institute for Health and Care Research (NIHR) Health Technology Assessment (HTA) programme.

For more information, please contact the BASE team at

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