DRINK PLENTY OF WATER!!! If you don’t normally consume the physician-recommended 64 – 80oz. of water every day, you should consider doing so beginning at least 3 days before your scheduled appointment. Hydration can significantly improve the depth and clarity of an ultrasound. Expectant mothers that are full-figured should consider scheduling their 4D ultrasound between 28 and 32 weeks of pregnancy, as the ultrasound tends to be clearer and the results more desirable and comparable to the images in our picture gallery.