Strengths and Limitations
Strength of our study is the inclusion of a low risk population; this could have reduced population selection bias. Even though the study involved more than one Centre, a single protocol was shared and the management of all the patients was homogeneous. In addition, the long term follow-up of children was crucial because several postnatal diagnosis were made after 6 months of age.
A possible limitation of the study is that not all patients underwent fetal karyotyping and CGH-array. In particular, postnatal genetic examination of liveborns who showed normal long term follow up was not performed and this could lead to the underestimation of genetic disorders.