Regular blood tests hould be taken when you are on a calcium supplement (particularly high dose supplements) as the calcium is prescribed as a calcium salt.
Any changes with the salt balance in your blood can produce other side effects which would be too numerous to list, but for example cause the effects of dehyration.
High calcium levels in the blood can cause muscles to work less effectively causing fatigue and if particularly high, could potentially mask an underlying pre-eclampsia.
Hypertension - high blood pressure can also be a symptom of high blood calcium levels which could (given the histories of the women in this community) be mis diagnosed as Pe when it is really an electrolyte imbalance.
All of this is pretty rare, but we know it can happen.
So for the sake of regular blood testing its worth monitoring throughout pregnancy.
Hope this helps, Ive tried to avoid being too 'sciencey' about it but can point you toward some references if you would like!
Every Woman is entitled to understand what happened in her pregnancy when pre eclampsia strikes. I hope to be able to support that process.