No... Down Syndrome is a chromosome deficiency that happens during conception when a spem and egg fertilize. Sometimes the X and Y Chromosomes don't add up correctly and can (sadly) cause this deficiency. Water in the mother's lungs can cause pneumonia which can potentially harm the fetus due to lack of oxygen. But this cannot cause down Syndrome. Water in the baby's lungs will also not cause Down Syndrome.
As a patient care manager, your should help out with their deeds