4D Ultrasaound

It is week 30th and I am intrigued to have a 4D ultrasound. The nurse at my doctor office said that the best week to have a 4D ultrasound is before week 32. Is it a splurge or a necessity? That is the question my husband asks. Well here is my take on it: I am looking at the 4D experience just like taking a vacation picture. Either you take it now or never...