This was a brilliant return to the grittiness of the first season or two.
Those contained shocking stories (see the incest/prostitution story of the young girl in the ship) and portrayed the shock of the new (Jessica Raines) midwife as naive and genuine.
The slightly patronising switch in later episodes to the clever, educated middle class midwives having the 'correct' view when the local population failed to understand just how normal those gays and disabled people were has been very problematic.
This used the whole 'new midwife' who is a bit green storyline to return the series to its roots, and I loved it.
Letting women speak is actually quite a subversive act, and that is what the BBC has done so well here.