No one can predict a medication's side effects.
What I can tell you is that the generic is not exactly the same as the brand. It has the same active ingredients, but the formulation is never the same as from the original manufacturer (Pfizer, in this case).
Pfizer's website says that there are possible side effects during pregnancy and to have a discussion with your physician.
Having been in the pharmaceutical industry for a long time, I'd not advise you to take it unless you feel comfortable. I opted to stop most of my medications during pregnancy unless the FDA had specifically approved them for that use (Zoloft is pregnancy category C).
This is the professional reference approved by the FDA regarding the product. Search for "Pregnancy" to see the information. It is a clinical document, so you may need your pharmacist/physician to review it with you pending your comfortability with scientific/clinical information:
http://media.pfizer.com/files/products/uspi_zoloft.pdf
I'd ask if there are any antidepressants that are approved for use during pregnancy and see if switching helps you.
If it were me, I'd discontinue and see how you do without the medication in the best interest of the baby. If it's unmanageable, I'd work with your physicians on finding the safest possible product on the market. Again, there shouldn't be a reason that the generic version has a different effect on pregnancy, but it is NOT the same as the branded medication, so the only information available is from what Pfizer submitted when they were researching/marketing the branded drug.