"Another baby"

I looked at J, my mouth open, he was sort of laughing, I guess it was a mild form of hysteria.
The Consultant looked at me, and then at J, "You can swear if you want to" he said.
"Bloody Hell!" said J.
"Well there's no question about the nuchal scan now," the consultant laughed "Twins calls for a nuchal, serum screening isn't effective diagnostically when there are two babies".

We don't have a family history of twins, as far as we know there have never been twins in J's family, and though there have been in my maternal line they're identical twins and the other half of their make up is a genetic line packed with identical twins. My father's family is a bit of a mystery, his mother having been a foundling and his father a secret she took to her grave, but the one set of twins there that we know of was again identical,  and again the clearly apparent in the non-family side of the line.
The most likely cause factors were that I was now 40, though that's the lower end of the age at which the odds of twins starts to increase, and I had had previous children.

We were told that as far as the consultant could make out there was a clearly defined lambda between them , signalling that they each had their own amniotic sac, and that the shape at the base of this suggested that there were also two placentas.

"So they're not identical?" I said.

But apparently that's no longer thought to be the case, while one sac, one placenta twins are definitely identical, whether they have one each, or share, very much depends on how early the little bundle of cells holding the recipe for life splits.  Twins of the same sex can only be correctly identified, we now know, short of very obvious differences, by DNA testing. There are lots of adult twins out there who don't know that they are in fact identical.

Still two sacs and two placentas was very good news, it means that this is the least risky type of twin pregnancy, the more they have to share, the more dangers they face.

We left with a date booked for a nuchal scan and sat in the car for a while...

"Two babies!" I think those are pretty much the only words either one of us said for a few hours, "Twins!".