nope giving birth actually changes your brain chemistry, 'mommy brain' is actually a scientific phenomena. They say a mom's brain doesn't return to normal 100% until the child is about 1 year old.
Part of it now is certainly lack of sleep, but it's also something more long term that you're going to have to adapt too. the easiest thing to do is adopt habits. If you ALWAYS put your keys by the door, it doesn't matter if you forgot where they are because they're by the door, KWIM?
good luck and congrats on the little one.