The ductus arteriosus is the artery that connects the aorta and the main lung artery. This artery acts as an opening that allows blood to bypass the lungs during foetal development. After birth, the lungs become fully developed and the opening is no longer needed. It usually closes a few hours or days after birth. However, if this opening remains open it is called a patent ductus arteriosus (PDA).
The precise cause of a PDA is still unknown. However, there are some factors that increase the chance of development of this defect. Prematurely born babies are likely to develop a PDA as their blood vessels are not completely developed at the time of birth. Genetics may also play a role. Moreover, family history of heart problems may influence the probability of the baby developing a PDA. Babies born to mothers who suffered infections such as German measles i.e. Ruebella during their pregnancy can also develop a PDA. A PDA is also twice as common in females than males.