Breastfeeding premature babies — often born with an abnormal heart — can improve heart structure as well as functioning in adulthood, finds a new study.

The findings showed that people who had been exclusively fed on breast milk had less reduction in heart volumes and function compared to those fed only on formula milk.

“The study shows that even in people whose premature birth has inevitably affected their development, breastfeeding may be able to improve heart development,” said Adam Lewandowski from Oxford University.

Previous studies have shown that, in adult life, the hearts of people who were born very preterm have smaller chambers, thicker walls and reduced function.

“Even the best baby formula lacks some of the growth factors, enzymes and antibodies that breast milk provides to developing babies,” Lewandowski added in the paper published in the journal Pediatrics.

The change in the heart emerges only in the first few months after birth. Thus, the team explored whether the way the baby was fed during this time might be able to alter how the heart develops.

For the study, the team followed 102 individuals, 30 of whom had been randomised to being fed exclusively human milk and 16 to being fed exclusively formula milk.

As a comparison group, an additional 102 individuals born term to uncomplicated pregnancies were also recruited.