So sorry that you are having to deal with this. I have no experience regarding SAA and pregnancy, only SAA with my husband. Like you, my husband was a picture of health and 9 months prior to getting diagnosed, he had physical which he passed with flying colors.
The one thing most can agree on is to have a doctor who is experienced with treating Aplastic Anemia. It's such a rare disease. If you haven't already, it would be worth exploring a consult with the NIH, Dr. Young. Or Dr. Brodsky at Johns Hopkins. Both have a lot of experience with treating SAA.
In the meantime, if you haven't done so already, rule out the easy stuff:
Rule out nutritional issues. Some of the basic things to check are vitamins D, B12, folate, copper, iron and zinc levels. These are the key nutrients involved in blood production. MMA and homocysteine levels will further help in assessing B12. B12 should be over 400. A low normal would be suspect. Pregnancy can place a burden on your nutritional status.
Hormones can play a role. So having your estrogen, progesterone, testosterone and thyroid could be helpful to identify issues that need correction.
Also, gastric issues, like being positive for h.pylori bacteria which causes ulcers can also impact bone marrow. It's easily tested. If you've never been treated for then I think it's just a blood test. Otherwise, I think they test your breath.
Finally, keep track of all your labs. Get copies of the results. Keep a spreadsheet of your CBC to watch for trends. Don't rely on a single CBC. Counts fluctuate so a one time CBC can be misleading. What are your counts now? Are all three line effected?
Marlene, wife to John DX w/SAA April 2002, Stable partial remission; Treated with High Dose Cytoxan, Johns Hopkins, June 2002. Final phlebotomy 11/2016. As of January 2017, FE is 233, HGB 11.7, WBC 5.1/ANC 4.0, Plts 90K.