Hi there,
I had one transferred with my 1st IVF and had compliacations during pregnancy resulting in a very prem baby. We were lucky not to have transferred 2 and as a result will only transfer one.
I suppose it depends on what your complications were in your first pregnancy and the liklihood of this occuring again. I tend to think that the FS usually knows what they are talking about and would be making an educated assessment of the risk.
The decision is, however, yours to make. Goodluck! I hope it all goes well.