2.2. Selection of the Cases

The selection of the cases of pregnancy in women undergoing egg-donation included all patients who delivered at the Sant’Anna Hospital between January 2008 and February 2019.

Pregnancies from egg-donation were identified in two main sources: the first was the hospital’s discharge database in which medical history, birth data and discharge letters are recorded. The search was carried out using the Italian keywords related to “egg-donation” in various combinations (e.g., “ovodonazione, ovodonazioni, ED eterologa, OD, fecondazione eterologa”). Secondly, we searched the computerised records of pregnant women referred to the Prenatal Screening Center at the Sant’ Anna Hospital, where information on type of conception is mandatorily recorded (egg-donation, other types of assisted fertilisation techniques, spontaneous pregnancy).

Low-risk pregnancies were selected from the TOCOS archives (TOrino Cagliari Observational Study [21,24]). In this study, low-risk pregnancy is defined as a spontaneous singleton pregnancy occurring in a woman without pre-existing, systemic and localized diseases. The database presently gathers 1407 Low-risk singleton pregnancies observed in the two settings in the period 2009–2016.