If you've only ever seen grainy, black-and-white 2D ultrasound images where you need someone to point out which blob is the baby's head, 3D and 4D ultrasounds are going to blow your mind. Instead of flat, two-dimensional slices, advanced prenatal screening tests...

Ultrasound scans are one of those things most pregnant people just accept as part of standard antenatal care without really thinking about why they're so important. You show up, lie on a table, someone smears gel on your belly and waves a wand around, and you leave...