Naresh,
I did some reading to try to find answers for you. I think the answers to your questions depend on whether she had
inherited pure red cell aplasia, also called Blackfan Diamond anemia, or whether she had
acquired pure red cell aplasia. The medical report doesn't seem to say. If she had acquired pure red cell aplasia then it would help to know whether it was idiopathic (from an unknown cause) or if the cause was identified.
Acquired pure red cell aplasia is usually not inherited or passed to children. In contrast, Blackfan Diamond anemia can result from mutation to specific genes. About half of people with Blackfan-Diamond anemia inherited it from a parent, and they may pass it along to their children.
Pregnancy can stress the bone marrow, so anyone with PRCA should consult medical professionals before planning a pregnancy.
This article from 2008 says that hormonal stress in pregnancy can apparently contribute to relapse for people who have had Blackfan Diamond anemia.
This article, from about the same time, discusses relapse rates for acquired PRCA but calls for more research. I wasn't able to find a more recent report on relapse rates for someone who had a success recovery years before.
I suggest gather a few more facts about her prior illness, then posing these questions to a doctor who is familiar with pure red cell aplasia.