The show is based on the memoirs of an old nurse, Jenny Worth, and though Worth has died and her original writings ran out at the end of the second series, Call the Midwife has become such a hit that the show had to go on, so go on it does.
We're now nearing the end of its third series, with a Christmas special and a fourth series to follow shortly from the BBC.
You can get too much of a good thing, but in the case of Call the Midwife, not just yet it seems. And the show is a good thing if you enjoy being suffused with a flood of feelgood nostalgia, heavy on the bittersweet.
And also, as mentioned, the show is quite keen on the births. There was one at the beginning and the end of Sunday's episode, but I coped, taken up as I was by all the goings on at Nonnatus House.
The series has the lustre of money. It's artfully made and soundtracked and acted. There's even a voiceover that pops up ponderously now and then, from Vanessa Redgrave as the old nurse, setting the scene, honking on about "the tender gift of time" and such.
But it's all part of the period charm, that and the mostly-female lead characters, who come in two tribes - lugubrious old nun nurses, weird in their wimples, and the young nurses, in their uniforms and hopeful dresses.
And then there's all the variously troubled young mothers to be - and the mostly-hopeless men. The best character is posh clumsy Chummy, having trouble with her horrible mater.
I'll be watching it on Sunday, though I may look away during certain scenes.
If it's more of this sort of thing you might want, then there's a new series called Love Child (TV One, Thursday, 8.30pm) which, like Call the Midwife, bats above average on a sticky wicket.
This series is Australian and you shouldn't let that put you off, though I have to admit I wouldn't have watched it unless I'd been ordered to.
This series too centres around a maternity hospital of sorts, this one in Sydney's Kings Cross in the late 1960s. And it too looks marvellous and boasts a pop-tastic period soundtrack.
And though it's a soapish spin with the lives of the nurses and their patients and the odd dodgy doctor, this is a darker story, set in a babies-for-adoption centre where pregnant girls are locked up until delivered of babies they never see.
Compelling actually, though again, there are those birth scenes.