Building a New House While Wife Is Pregnant

My wife and I are trying to decide if we start building a new house in september or if we should wait until after our baby is born in early january. We are afraid that we might loose a good opportunity that has been presented to us if we wait until next year, but i'm afraid (more so than my wife) that building a new home from the ground up might put too much stress on my wife. There is always something that goes wrong when you build a new home and this one would not be an exception. The last thing I want is that our baby suffers because of everything that will be happening while we build the house.

I need opinions about this because i'm not sure of what to and we need to decide within one week.

Thank you in advance.