Scientists found that they could use chain of amino acids like a honing beacon to target parts of placenta selectively, which could improve placental function and help the baby to grow without causing it harm.
These chains, known as peptides, were used originally to target tumours but researchers realised they could be used for other purposes. There are currently no drugs that can be used to treat issues such as pre-eclampsia or foetal growth restriction, which affect more than ten percent of pregnant women.
Instead doctors have to induce early delivery of the baby, putting the child at risk of developing infections and cerebral palsy.
Lead researcher Dr Lynda Harris, of Manchester University, said: “Placentas behave like well-controlled tumours. They grow quickly, produce growth hormones and evade the immune system.
“A lot of cancer research focuses on finding ways of delivering drugs to kill the tumour without affecting the rest of the body.
“We had the idea that if we could selectively target the placenta in the same way, we could deliver other drugs which help improve placental function and therefore treat pregnancy complications.”
A growth hormone delivered to placenta in mice had no effect on normal-sized foetuses but helped the smaller ones to grow, according to the paper published yesterday in Science Advances journal.
There were no signs that these drugs built up in the mouse’s organs, instead passing out of the body.
It could have a harmful effect on mothers with undiagnosed cancers, because the drugs will also target their tumours, but the authors suggest a screening programme would overcome these difficulties.
Professor Melanie Welham, Biotechnology and Biological Sciences Research Council chief executive, said: “The findings could help develop therapies that can help both the mother and unborn baby.”