Researchers at the University of Leeds have identified a key stage in the development of a baby's heart which could help them reduce the number of miscarriages.
One in 10 miscarriages is believed to be caused by the failure of the heart to form normally. Now new imaging techniques have shown that the four chambers of the foetal heart develop in just four days.
The research, published in Nature journal's Scientific Reports, took images of 23 foetal hearts between 95 to 143 days in the womb. The hope is these findings will mean doctors could intervene when a baby's heart fails to grow properly.
Dr Eleftheria Pervolaraki, BHF Fellow and lead researcher at the University of Leeds, said: "We have identified a critical time of development of the human heart in pregnancy.
"We have used a technique developed to give us higher details than ever before.
"When all the fibres, muscles and cells achieve the formation needed to see in an adult heart, when they all do that you have a fully-formed organ free of risk.
"If it doesn't reach that state it leads to an additional risk of miscarriage."
Identifying when the chambers develop means doctors could eventually monitor babies during this critical phase. Currently doctors can only effectively monitor a baby's heart after 20 weeks (140 days).
The images used MRI technology and 3D computer software and found the "most remarkable changes" occurred at 124 days into the pregnancy. Without this four-day development the foetal heart cannot survive outside the womb.