This is the second of two additional questions that have Biblical references.
Q: Why did Jehovah bring about the 10 plagues of punishment against the Egyptians including the Death of the First Born Children?
A: Once again we have a misinterpretation of a catastrophic phenomenon which is attributed to the wrath of Jehovah.
Many people in that era were in-bred and as a result were lacking in a robust immune system.
Also, medical understanding of disease in that era was non-existent, cleanliness was poor as well and nourishment limited. This allows disease to spread fast. As a result a number of diseases (plagues) devastated the population and mutated , devastating those who survived the first diseases and then the second, etc. etc.
Young babies have a very weak immune system and so they were susceptible to contracting the disease and dying. As many families were young and having their first children, those that were borne in the time of the plagues were the ones that contracted the disease and died. The report being that the first born were being punished was therefore consequential and not the result of the wrath of Jehovah.