I had one FS tell me to stop as soon as I was pregnant, another tell me to take it until at least 12 weeks, an OB who was happy for me to take it and a GP I could convince to keep prescribing on the advice of the FS who said to keep taking it...

It could be coincidence, but my first miscarriage coincided with reducing the dose of metformin. Not stopping it, just reducing it. I was paranoid. I didn't start reducing the dose until I was 17 weeks and didn't stop taking it until I could feel regular movement. I was a bit paranoid, though.