Maternity bra fitting - help!

[SpanielFace]

I'm 28 weeks pregnant and really need to buy some bigger bras. I'm currently wearing a 38DD which are clearly too small and the underwriting is digging in (I was a size 18 pre-pregnancy, so a 38 is probably right). I am getting totally confused by measuring guides online! My measure bra are:
Below the bust: 41 inches (!)
Around the breasts, bending over: 48 inches.
So, I know to ignore the guides that tell you to add inches to the band measurement. So, a 40G or a 42FF? Have I got that right? I'm going to pop to M&S tomorrow, but have had some bad experience with being fitted wrongly there in the past.

Yes, that sounds about right.

When you're fitting maternity bras you need to fit on the tightest hook, rather than the loosest hook (as you usually would). The ribcage keeps expanding - as you've probably noticed

Fitting on the tightest hook means that you're effectively taking the bra down a band size so you need to take that into account in the cup. One band size up is one cup size down, more or less. So, if a 42FF fits perfectly on the loosest setting a 44F should fit more or less the same on the tightest setting as the cup volume is the same. I hope that makes sense!

I'd try the 40, 42 and 44's in F, FF and G and work from there. Also, if you're thinking you might breastfeed then it's worth buying feeding bras rather than maternity bras - they'll all fit at some point on the way back down. The price is about the same, or, well, it was in my day.

fitting info here

Thank you, that's really helpful. I wasn't going to get nursing bras yet because I know I grew again after DS was born, but you are right, they would probably fit on the way back down, and even if they don't, I've not wasted anything. I got so frustrated with DS as to how much my size changed - I have about 10 bras in 3 different sizes, none of which fit this time as I'm about 3 stone heavier. Which is why I've been squashing myself into too-small bras this time! Right, I'll see what M&S have got to offer. Thank you.

One more point. ..wires are fine so long as they fit you well - in pregnancy and when feeding.