Well, not knowing what is going on I wouldn't jump to conclusions. For all you know they had to rush her for an emergency c-section (god forbid) and things just went crazy and your brother just hasn't had the time to think of anything or anyone else. I'm sure that once things settle down he'll let you all know. I would just back off and let them do it on their own time. After all it is their first baby and you know how overwhelming things can get.
Now if the baby was born and you don't hear from them in a while, I would be upset too, but what can you do right.