And just to add to the below...
How amazing is the human body? That it can contort itself for a few minutes (as in Wednesday's case) and change shape? Some time hopefully in the next week, it's going to contort itself some more and extract a baby from between my legs!

What is it in the body that tells it to do things like this in the late stages of pregancy? What clicks the body into "going into labour mode"? For the record, I don't think anyone knows down to the molecular level yet, but there are a lot of factors that can influence it, including: stress, semen (ahem), certain essential oils (clary sage & rosemary are some, according to what my hospital booklet tells me).

Amazing!