Thank you for your query.
You experienced eclampsia - that is seizures ( fits ) due to high blood pressure
This condition causes severe constriction ( narrowing ) of the blood vessels, including placental blood supply, due to severely raised blood pressure.
Also yours was a most complicated case, as the kidneys also were severely affected.
The cause for fetal death
is abrupt decrease in the blood supply, already aggravated by chronic changes in the placenta caused by hypertension
There is absolutely no way to determine the time of the death, because when you went for ultrasound
, the baby was already dead.
however, as it was a fresh stillbirth, it could not have been more than 24 - 72 hours, as then maceration sets in.
Please be careful and have detailed investigation and testing, as eclampia has a recurrence of 25 % for the next pregnancy