If you mean from the episode "Emission Impossible", then it's Bertram. And he actually is born in "Sibling Rivalry" when Peter goes to get a vasectomy, decides to freeze his sperm before hand, winds up accidently destroying the other specimens in the storage room, and has to fill up every jar in order to cover his mistake. Then the two lesbian (Meg's gym teacher and her girlfriend) ask for a donor so they can have a child. 9 months later-BAM! Bertram's born to battle Stewie once again...
Rupert
Brothers
brothers of destruction
The Shining, Happy Birthday To Me, The Unborn
Yes, to a girl name Alice. She was pregnant. Her and her unborn child was killed.
Bertram
pLace
He doesn't have one. He does however have a younger half-brother named Bertram, at least "younger" in the respects he was born after Stewie but in his 2 appearances after he was born he appeared the same size and age.
September 11th
Rupert
An unborn baby is referred to as a fetus, or foetus.
Flangarhmoohgarden Diocide. Which translates loosely to "swine unborn".
familyguyepisodes.com
an Orthodox
To kill Lois and the Fat Man AND take over the world
Nothing
Unborn Baby.