My midwife said to me (DD was posterior in late PG/early labour, despite me trying all the tricks) that some babies are a bit tangled in their cords, some babies mums spend a lot of time sitting leaning a bit back - like on sofas etc. - apparently posterior labours are rarer in countries where squatting round a fire/kneeling is still a common way of spending time, the western way of sitting leaning back in cars/sofas/recliners/office chairs etc. is not helpful as bubs gets heavier. I was told to sit backwards on a dining/office chair or sit on a beanbag with my knees lower than my hips as much as possible. She also said that for some bubs the inside of mum's pelvis is more comfy for them if they stay posterior. Chiropractors can sometimes help with that as there's a move they can do which re-aligns your pelvis a little. Apparently the majority of babies turn during labour, during the late 1st stage. In my case i had 11 hours of pre-labour (only about 2 or 3 hours of that was actually work though) with back pain in between contractions as she was posterior and once she turned she came FAST. I was lying on my back in the bath for a lot of it, and once i got out things suddenly sped up. She was posterior at 1st VE and crowning at 2nd. Apparently early labour is a really good time for bubs to get well-positioned so it's good to be comfy, upright and active during the 1st stage to give bubs a good chance to get bundled up right for the ride down and out. Some women seem to have posterior bubs. I have a friend who had all 3 of hers posterior. There's a particular pelvis type which i think can be more prone (is this in the Pink kit?). It's by no means inevitable, it's just a tendency, and there's masses you can do to help.

If you're in a posterior labour there's things your assistants can do for you, like providing counter-pressure on the back of the sacrum, applying a heatpack to your sacrum, and some massage techniques which Sheila Kitzinger covers in her Pregnancy and Birth, which make a BIG difference.

I think with posterior bubs, the chances are they'll turn. You can do moves to help them turn and learn techniques in case they don't turn. It doesn't mean you're in for a terrible labour; with the informed help you might have a FAR easier labour than a woman with an anterior bubs but no birthing skills/knowledge/doula. Yet another time when knowledge is power.

Bx