Waiting for mums' milk safer than thought for preterm babies

It seems intuitive: babies born a bit early would benefit from being bolstered with a bit of extra feeding while waiting to get to full breast milk feeds.

But it seems they are more resilient than we might have thought. 

A Liggins Institute-led study published in the New England Journal of Medicine looked at 530 babies born between 32 and 36 weeks and already receiving some intravenous fluids. Researchers tested giving extra intravenous protein and/or additional milk (usually infant formula) to some of the newborns, in addition to the standard intravenous fluids.

They found doing so didn’t get the babies to full breastfeeding any quicker than when doctors just waited until their mums’ milk kicked in.

It also didn’t change how much fat they had or their growth at four months of age.

Since most of these babies are initially too preterm to know how to suck, the researchers did another randomised study intervention, where some babies were exposed to the taste and smell of milk prior to getting feeds via a tube into their stomach. Once again, they didn’t find any difference to how long it took to get babies onto full normal feeds – and therefore be able to go home.

Six researchers on the study were from the University of Auckland, of which five, including lead author Dr Tanith Alexander, were from the Liggins Institute. One author was from Middlemore Hospital’s Neonatal Unit.

Professor Frank Bloomfield, Deputy-Vice Chancellor Research at the University of Auckland and one of the study’s authors, says hospitals and families aim to get babies home as quickly as possible, but most moderate-to-late-preterm newborns need some sort of nutritional support pending full feeds with their mother’s own milk.

The trouble is, it’s not clear what to give them.

“There are various options, but no evidence about what’s best, which leads to a huge amount of variability.”

Doctors worldwide endorse breastfeeding, he says, but there are no evidence-based guidelines around best-practice nutrition before a baby’s mum is producing enough breast milk.

“We decided to test three options at the same time.”

 "It made for a complicated study design, with eight different treatment conditions: all the babies got an intravenous dextrose (sugar) solution, but on top of that researchers looked at whether extra intravenous protein, extra milk, and/or allowing babies to taste and smell milk before a tube feed, got them onto full feeding with only their mothers’ milk more quickly than not receiving the additional interventions. And thereby whether they got home more quickly. And they didn’t.“

"There was no difference for either outcome with any of the interventions,” Bloomfield says.

“That’s important because it tells us there’s no need to give formula or an expensive intravenous protein solution to most moderately preterm babies whose mothers want to breastfeed – it doesn’t change their fat mass.

“Instead it’s quite safe to wait for the mother to have enough breast milk, supporting them with simple intravenous fluids.”

Would the additional feeding do harm?

“If mum is sick or can’t provide milk, then these babies will need additional support and there’s no harm in giving extra formula milk or intravenous protein,” Bloomfield says.

“However this study shows that in moderate-to-late preterm babies whose mothers plan to breastfeed, short term additional intravenous protein or formula is not necessary.”

Avoiding intravenous protein solutions is not just a significant cost saving, but means if there’s a problem with the drip and if the solution gets into the skin, it causes less damage, Bloomfield says.

There might also be benefits in terms of the baby’s microbiome from avoiding giving a baby formula, but that’s not yet clear.

“We know that infant formula results in a different microbiome, at least in the short term, but we don’t know what the consequences are of that – whether it’s a bad thing or not.”

The next step in the research is seeing how the babies are doing now.

“We’ve almost finished assessing the babies at two years. Then we will be able to answer the question as to whether development at two years is different depending on nutritional supplementation.

“We will use that information to write national nutrition guidelines, so wherever you are in the country babies receive the same evidence-based care.”