The Advisory Committee on Immunization Practices considers healthy women who expect to be past their 14th gestational week during influenza season to be at high-risk of influenza-related complications. In 1997, influenza vaccination was recommended for such women, however, the level of compliance with this recommendation is uncertain. A retrospective cohort study is being conducted to further assess the effect of influenza on maternal morbidity and pregnancy outcome. Rates of influenza-related health care contacts and risk of preterm birth are compared for periods of peak influenza activity and peri-influenza periods. The study population includes healthy women enrolled in a Northwest HMO, who could be linked to a live birth certificate between 6/1/92-12/31/97, and were continuously enrolled for ³365 days before their first study delivery. Computerized medical records, birth certificates, and cancer registry data have been collected for each woman. An index of weekly influenza activity has been constructed through ratio and time series assessment of regional isolate data. Crude and adjusted rate and risk ratios are used to assess the effect of influenza activity on influenza-related health care contacts and preterm delivery using Generalized Estimating Equations to account for correlated data. Strengths of this study include: attention to exposure timing, focus on healthy women, comparison of women in the same gestational stage, and inclusion of individual-level covariates. A limitation is the lack of confirmed infections, however, the required prospective study is restrictive. Overall, the present study strengthens the body of research used to inform vaccination choices.
Learning Objectives: N/A
Keywords: Infectious Diseases, Maternal and Child Health
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: Group Health Cooperative
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.