Background and aim of the study: Pregnancies obtained by assisted reproductive technology (ART) are associated with an increased risk of complications and congenital anomalies, particularly congenital heart defects (CHDs). Therefore, our aim is to evaluate, retrospectively, the prevalence of CHD in ART pregnancies in our two centers and analyze their characteristics and outcomes.

Methods: Observational study including fetuses conceived by ART referred between June 2011 and September 2020 and undergoing a fetal cardiac ultrasound scan. Cases with genetic, chromosomal abnormalities or extracardiac malformations were excluded. Population included 1511 pregnancies, which consisted of 269 twins and 1242 singletons, 547 IVF (in vitro fertilization), 773 ICSI (intracytoplasmic sperm injection) and 191 oocyte donations (OD).

Results: CHDs were found in 29 fetuses, with an overall prevalence of 1.92% (29/1511), 1.85% (23/1242) in singletons and 2.23% in twins (6/269). Thirteen were IVF, eight ICSI and eight OD cases, with a greater risk of CHD after IVF and OD (IVF: 13/29 (44.8%)-one twin; ICSI: 8/29 (27.6%)-three twins); 22 had major and 7 minor defects. Two pregnancies with a hypoplastic left heart were terminated; the majority of live-born cases needed surgery. Three babies died (two post-surgery, one had a late death).

Conclusions: Our data show an increased prevalence of CHD after ART with a heterogeneous spectrum of diagnoses, mainly major defects.