it's a...

she is very active.  she has a cute little belly.  she is healthy.  she is our little girl.

plus...she gave the ultrasound technition what she called a "textbook shot" of her lady parts.  textbook, huh?  well done, little lady.   looks like you are obedient [thank you for cooperating, as i asked], thorough, and kind of a nerd with your "textbook" poses.   we like your style already.