Now that you, Rosie, have refreshed my memory in the other topic, I can think a little clearer in this one. SO......There was either a mishap at the sperm bank (Sami, Vivian or Kate), or Susan was involved in some other hanky panky (one of Stephano's minions) while Stephano was trying this artificially.
I think I have to wait and see what the writers decide, but I'll be trying to second guess them the whole time.
"Life isn't about waiting for the storm to pass...
It's about learning to dance in the rain."