Background: Rubella infection in pregnant women, especially in the first trimester, can result in serious neonatal morbidity and mortality. To stem a series of rubella outbreaks in Thailand (in 1967, 1974 and 1978), the Ministry of Public Health launched the National Expanded Program on Immunization (EPI) in 1986. The Mump-Measles and Rubella (MMR) vaccine was given to all graduated primary school girls.
Objective: To determine the immune status to rubella in healthy pregnant women visiting the Antenatal Care Clinic (ANC) at Srinagarind University Hospital.
Design: Descriptive study.
Setting: Antenatal Care Clinic at Srinagarind Hospital.
Material and Method: Between January15 and May17, 2004, 150 normal pregnant women (between 15 and 40 years of age) were included. After a complete history was taken and a physical examination performed, informed consent was signed; serum was collected for testing for rubella antibodies at the same time as routine prenatal check up in normal pregnant women including CBC, red blood cell indices, Rh blood group, VDRL, HBs Ag, and AntiHIV. The ELISA technique was used to detect maternal rubella IgG antibodies.
Outcome measure: Rubella IgG antibody level.
Results: Three-quarters (112/150) of the pregnant women had immunity to rubella, 7% (11 cases) were indeterminate and 18% (27 cases) had no immunity.
Conclusion: The cost of screening for rubella IgG antibodies was 150 baht using the HAI technique and 350 baht/case using the ELISA technique. The latter is more available but twice as expensive, so repeating rubella immunization for all high school females would be more cost effective and provide more certain protection.

Keywords: Rubella IgG antibody, Rubella titer, Rubella vaccine, ELISA