Due to current medical improvements, more women with cardiac disease are being operated during pregnancy. Fetal loss has been found to be significant between 9-30% of them and the surgery is supposed to be done maximal in the first trimester.
Ngo Nonga, B., Pasquet, A., de Kerchove, L., Glineur, D., Debiève, F., Hubinont, C., El Khoury, G., & Noirhomme, P. (2013). Emergent cardiac surgery with cardiopulmonary bypass in early pregnancy: report of four cases. Research in cardiovascular medicine. https://hdl.handle.net/2078.5/193033