1. Babies bring "good luck" or "prosperity": In some cultures, newborn babies are regarded as a symbol of purity and vitality, and are associated with good luck and prosperity. Therefore, if a family has just given birth to a child, people may think that the house has been shrouded in this kind of "good luck", which may lead to other positive events.
2. Concepts of "purity" and "impure": In some cultures, newborn babies are regarded as a symbol of "purity", and renting in such a house may be considered as an inappropriate mixed behavior.
However, these are based on traditional ideas and beliefs, and everyone's views may be different. Modern views may be more open and rational. If you are uneasy about this situation, you can choose to communicate with the landlord to find out their views on this matter. If they also understand and respect your concerns, then you can find a solution together. For example, you can choose to move to another house, or let them redecorate the house to get rid of the impression of "good luck" or "impure" that may be left.
The above are just some ideas based on traditional ideas, which are not applicable to all cultures or regions. You need to decide your opinion according to your own values and cultural background.