You can't get Gwen pregnant yet, for a few reasons...
In-game Reason: Gwen and Chloe took full-power Awaken and Shatter respectively, and so the massive amounts of raw power flowing through their bodies makes getting impregnated by you highly dangerous.
Mechanical Reason: Gwen and Chloe show up in way too many questlines for me to create a render variant/if-else branch for every single one.
Gwen and Chloe will be able to get pregnant eventually in Act Three :)