Volunteers needed for RSV maternal antibody study at the IWK Health Centre Halifax. Respiratory syncytial virus (RSV) is the most common cause of hospitalization in children under 5 years old. This study measures mother's antibody protection passed to her newborn. It does not involve any drugs or vaccines. We are looking for pregnant women between 20-42 weeks gestation who are over 18 years of age and expecting a healthy baby. For more information go to http://www.centerforvaccinology.ca/study/rsv-maternal-antibody-study/ Study recruitment is open until the end of June 2015.