2. Materials and methods
2.1. Study characteristics
We made a cross-sectional study of women who gave birth at
the Hospital Clinic of Barcelona (HCB) between January 2008 and
December 2013.
2.2. Rubella immunization practices
In Catalonia, an autonomous region in the northeast of Spain
with nearly 7.5 million inhabitants, rubella-containing vaccine was
introduced into the routine immunization schedule in 1978 for all
girls aged 11 years (women born after 1967) [14]. In 1980, in order
to improve measles control, the MMR vaccine was introduced in
children aged 15 months. In 1987, the MMR replaced the rubella
vaccine at 11 years of age. In 1998, the age of administration of
the second MMR dose was advanced from 11 to 4 years. Finally, in
2008, it was recommended thatthe age of administrationofthefirst
dose of MMR should be changed from 15 to 12 months [15]. Similar
schedules for rubella-containing vaccine have been introduced in
other Spanish regions [8].
2.3. Laboratory methods
Following the recommendations of the Department of Health
of Catalonia, serological screening for rubella was made in all
pregnant women during theirfirst blood test, which is usuallymade
during the first trimester of pregnancy [13]. Levels of rubella IgG