La frequenza dei parti gemellari è raddoppiata dagli anni '70 nei paesi ricchi e la Svizzera non fa eccezione: da 8,8 ogni 1'000 nascite si era passati a 16,4 già nel 2005, secondo uno studio pubblicato dalla rivista "Population and Development Review". Il motivo, secondo i ricercatori, è semplice e conosciuto: il ricorso alle fecondazioni in vitro.
L'inserimento nell'utero materno di diversi ovuli fecondati aumenta considerevolmente la possibilità che in caso di gravidanza si sviluppino più feti. "Non siamo sicuri che le cifre continueranno a crescere, ma sempre di più vengono considerate come una vera e propria crisi sanitaria", spiega il co-autore Gilles Pison.
I parti gemellari sono infatti più pericolosi per la madre, i bambini nascono spesso prematuri, pesano di meno e hanno maggiori possibilità di morire in tenerissima età.
pon/ATS
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