Almost 62 percent voted in favour of changing the constitution to permit genetic profiling of embryos during IVF before implantation in the womb. The procedure will only be available for those unable to conceive naturally or carriers of severe hereditary diseases.
Currently in Switzerland screening for such conditions is limited and carried out prenatally at around 9 to 12 weeks of the pregnancy. If a genetic defect is found before 12 weeks, abortion is then a possibility.
The draft law would also allow embryos to be frozen and stored for future use. The current law means that all embryos created during IVF, up to a maximum of three, have to be implanted, which leads to a greater likelihood of multiple births and associated risks.
According to SwissInfo, both the main political parties and disability rights groups in the country have found themselves split over the referendum. Some have argued that the use of screening could lead to discrimination towards families who decide to proceed with a pregnancy if they know their child will have a disease. An additional concern for opponents is that the technology could be used to select for specific traits, commonly referred to as 'designer babies'.
However, supporters say that the current laws force parents to travel to other countries for PGD, or to undergo abortions that could be avoided. Additionally, there is specific wording in the draft law to prevent the technique being extended to non-medical uses. The constitutional change was supported by a majority in the Swiss Parliament as well as by the country's main doctor's association.
The vote in favour of PGD could, however, be overturned by a referendum if Switzerland's small centrist Protestant Party is able to collect enough signatures to force another ballot on the issue.
But Thomas Weibel, a parliamentary member of the pro committee, said that the results were too decisive: 'If the results were closer, it would be clear that they would be contested in a referendum, but now the opponents will have to reconsider.'
Outside Switzerland, most European countries, including the UK, already allow PGD, which has been used since the 1990s.