If there are new complications that were not evident during previous pregnancies it is possible it is related to the different partner. It isn't a pleasant question but today it is also wrong to assume that all children are from the same relationship and thus, potentially, miss an important piece if evidence when trying to provide the best care for the complication being treated (or not being treated on this occasion).

Not sure of the evidence to support this but it is a reasonably common question to be asked.