Italian wedding

A wedding in Rome.

Why is the bride wearing blue instead of white? According to Italian tradition, the bride should wear something old, something new, something borrowed and something blue on her wedding day, for good luck.

If you look at the divorce demography data, Italy has one of the lowest divorce rates in Europe - 0.9 divorces per 1000 people (in 2011) - compare this to Russia (4.8), Latvia (4.0), USA (3.6) or the average for EU (2.0).

Does this custom in fact bring good luck or could it be because divorce only became legal in Italy in 1970?