Usually when you hear someone talk about a birth ball they are referring to the standard yoga ball, which comes in three sizes – small (55cm), medium (65cm) and large (75cm.) You can find these at places like Target or Walmart for under $10. These are great during pregnancy for exercise & for sitting in a good position for optimal fetal positioning. During labor they’re wonderful for rocking, swaying, figure 8s, resting over while on all fours/kneeling, etc. Postpartum they’re nice for bouncing/rocking babies and exercise – when you feel up to it.
The other type of birth ball is the peanut ball, which I write about here. They are less common but increasingly more in use, whether moms are having an epidural assisted birth or going meds free. You can also find these at Target or Walmart for around $20.
I purchased the medium thinking it would be the most appropriate for moms with a variety of heights, but it’s actually too small – go with the large. Here’s a photo of them side-by-side and you can see the difference isn’t significant, but when you have a taller mom you’ll want even that little bit of extra height to ensure a more comfortable seat. Also be sure to keep the pump nearby, as they are much less helpful when they go flat.
I recently attended a hospital birth where they no longer had their own birth balls, citing liability issues due to hygiene. These balls are easily wiped down with disinfecting wipes and/or sprayed with a cleaner, and I’m not worried about it. Thankfully the hospital did encourage me to bring in my own ball.