Newborn with low platelets, what is diagnosis?

Thrombocytopenia. The name of the condition is thrombocytopenia. If real (test can be a false positive) the condition usually arises when the mom develops anti platelet antibodies that have crossed into baby & destroy its platelets. The condition can be major requiring rx or minor & will generally fade over time as the antibodies decline. Low platelets can also be a sign of infection in baby.
Be Careful. Dr ferguson's answer is correct. An additional reminder is to be a bit careful in handling the baby since low platel;ets allow a higher risk of bleeding internally with trauma. Also, if a boy-do not circumcise until better.