Rubella seroprevalence in pregnant women in North Thames: estimates based on newborn screening samples.

Objectives: Routine screening for rubella susceptibility is recommended in the UK so that women found to be susceptible can be offered immunization in the post partum period. We demonstrate the use of newborn dried blood spot samples linked to routine vital statistics datasets to monitor rubella susceptibility in pregnant women and to investigate maternal characteristics as determinants of rubella seronegativity.

Setting: North Thames region of England (including large parts of inner London).

Methods: Maternally acquired rubella IgG antibody levels were measured in 18882 newborn screening blood spot samples. Latent class regression finite mixture models were used to classify samples as seronegative to rubella. Data on maternal country of birth were available through linkage to birth registration data.

Results: An estimated 2.7% (95% CI 2.4%-3.0%) of newly delivered women in North Thames were found to be seronegative. Mothers born abroad, particularly in Sub-Saharan Africa and South Asia, were more likely to be seronegative than UK-born mothers, with adjusted odds ratios of 4.2 (95% CI 3.1-5.6) and 5.0 (3.8-6.5), respectively. Mothers under 20 years were more likely to be seronegative than those aged 30 to 34.

Conclusion: Our findings highlight the need for vaccination to be targeted specifically at migrant women and their families to ensure that they are protected from rubella in pregnancy and its serious consequences.