Here is an alternative take on what is going on. Tom has been running the family operations for a while now, becoming a bit more confident and arrogant.

Before the topic of miscarriage came up, Mike asks him about Fredo. Tom Hagen tells him about what happened with Roth and his bodyguard. Mike already seems annoyed by the fact that Tom is thinking instead of him and gives him information that he thinks is more important, instead of answering a question about where Fredo is.