Anyways, a baby is not supposed to poop while still inside the womb. But it does happen. Also, under normal conditions the baby inside the womb is in a sterile condition which means there are no bacteria around them. Even in their poop.

We call the poop of a new born baby or one still in the uterus meconium. It forms inside the intestines from the cells that are shed and other substance that are in the amniotic fluid.

So they pee and swallow, and in their gut form the poop which aids the development of the intestines. The baby "breathes" in the amniotic fluid to help develop the lungs also.

During labour, there might be some stress to the baby that may cause a reflex that makes them poo. It's usually during labour that this happens. Sometimes it happens spontaneously in babies who have passed their term.

For those who have experienced birth, they might have seen greenish-black stains in the amniotic fluid.

It's generally not unsafe but where babies pass too much of the meconium and it passes back into their mouths and suck it into their lungs when they're delivered, this may result in injury to the lungs which can be quite problematic.