Can a PDA be prevented while the baby is in my belly?

No. Pda stands for patent (meaning open) ductus arteriosus. The ductus arteriosus is an important structure that should remain open throughout pregnancy. After birth, it should close naturally within a few days.
Absolutely Not. A PDA is a normal part of the fetus's anatomy. With very, very few exceptions, closing the PDA in a fetus will actually lead to fetal demise. So, with rare exceptions, we would never close a PDA while in the womb.
You don't want that. The PDA is a normal bypass that allows the babies heart output to go directly to the body without passing through the lungs (which do nothing before birth).This reduces the work of the heart & allows the baby to use its energy to grow rather than do extra work. After breathing starts the increase in body oxygen level begins natural closure in most.