Is a complete hydatidiform mole and a co-existing normal fetus an iatrogenic effect?

Background: Complete hydatidiform mole and a co-existing normal fetus (CHMCF) is associated with a high complication rate. A possible association with assisted conception might increase the prevalence of CHMCF. Objectives: To study the potential association between assisted conception and the risks of CHMCF. Methods: Case series at a single university hospital from 2008 to 2018 are presented and contrasted with data from a comprehensive literature review (1998-2018). Cases were identified from the institutional database that matched the sonographic criteria for CHMCF. A literature review showed comparable cases. Results: None of the three pregnancies presented in this article resulted in a viable fetus, all were aborted. One of the three patients needed chemotherapy due to gestational trophoblastic neoplasia (GTN). A literature search identified 248 reported cases in which 22 fetuses (9%) reached term, 88/248 (35%) progressed to GTN, and 25/120 (21%) were conceived following assisted conception. From 2008 until 2018 at our medical facility, there were 3144 twin pregnancies of which 1667 (53%) were conceived using assisted conception. In our cohort, there was no statistical trend for assisted conception as an etiological factor for CHMCF. Conclusions: No association between assisted conception and the risk for CHMCF was established at our hospital, although approximately one-quarter of all reported CHMCF pregnancies are attributed to assisted conception technology. However, these data are not always reported, making it difficult to draw definitive conclusions.