**1. Introduction**

Since the most ancient times, mythical stories concerning twins were described both in religion and art [1]. Examples of twin gods and heroes are numerous: from the twin sons of Zeus to Rome's founders, Romulus and Remus. Such legendary conception connected to twins may still be found in contemporary primitive societies [2]. The evolution of medicine has led to a different perception of the twinning phenomenon, with several implications for the obstetric care [3].

The frequency of multiple pregnancies has been increasing since the 1970s. Contributing factors include the wide use of fertility drugs and assisted reproductive technologies, along with a higher number of women giving birth at older ages [4]. Nevertheless, many physicians still underestimate the adversities of multiple pregnancies. [5].
