Low platelets

Never experienced this in my first pregnancy and now suddenly my body is turning on itself. My platelets at the beginning of this pregnancy were normal. September 3rd I had my blood taken again and my results showed my CBC had all dropped drastically, but particularly my platelets had gone down from 300 to 77. Within a little more than a week my numbers have continued to drop to below 70. So about 8,000 in a week. I’ve been referred over to the oncologist/hematologists office and am waiting a scheduled time to come and see what’s going on. Just wanting to get an idea of what to expect or if anyone else has gone through this what to look for or know about.