You might want to direct this question to Dr. Gould on the mental health forum. I don't think he's too keen on any of these meds while you're pregnant, but he might know if Zoloft is somehow better than others.
Taking meds during pregnancy is always a personal decision that must be weighed very carefully...looking at the risks and the benefits. Personally, Zoloft has worked very well for me in the past, with the least amt of side effects compared to other meds I have been on (Lexapro, Prozac). I also took an antidepressant while pregnant, and my OB told me that with meds, there are NEVER any guaruntees that the med will NOT have some sort of negative impact on the baby, but also, these types of meds are commonly prescribed to pregnant women these days, with some AD's being considered "safer" than others.
To be honest, I would be more concerned about the Seroquel than the Zoloft. Does your OB plan on keeping you on BOTH meds? Seeing your psychiatrist is a great move, just be sure you run the plan by your OB before starting any new med. The Zoloft will take at LEAST 4-6 weeks to really start working...some people a little less, some people a little longer. Just be sure to keep in close communication with your OB. The fact that you are farther along greatly reduces any kind of developmental problems (as taking meds early in pregnancy during the rapid growth of the fetus presents more risks), however, there is a slightly higher risk that your newborn will display some withdrawal symptoms, such as being fussy, crying a lot, that sort of thing.
Again, just be sure to follow up with anything your OB recommends...and be sure to run any Rx that the p-doc suggests by your OB first.
Best of luck to you!
Like i said before it made me worse at times - I have decided to go to my psychiatrist tomorrow and ask him. He has me on seroquel