Parliament has decided in principle to ease restrictions on embryo screenings as part of a reform of the law on reproductive medicine.
Despite opposition by the government, the Senate on Monday followed the House of Representatives in allowing screenings of all in vitro embryos.
It is estimated that more than 1,000 couples a year might use the option. In March, the Senate wanted to limit embryo diagnostics to cases with suspected genetic diseases.
Opponents warned that the decision might lead to increased pressure on couples who use this type of artificial reproductive technology – a total of about 6,000 on average annually – to have embryos tested and destroy embryos with disorders.
Supporters argued it was not fair to permit screenings of embryos in wombs, while imposing restrictions on in vitro fertilisation (IVF).
Discussions in parliament are likely continue later this year to define the maximum number of IVF embryos.
Voters will have the final say on the constitutional amendment at a later date.
Urs Geiser, swissinfo.ch and agencies