Respiratory Syncytial Virus (RSV) is a virus that can cause serious lung infections in babies and young children. Recently, two new products were approved to help protect all babies from RSV: **ABRYSVO**, a vaccine given to pregnant women, and **BEYFORTUS**, a special antibody given to babies at birth. This study will see how well these products work by checking the antibodies (proteins that fight infections) in babies up to 12 months old. Some babies might get both products, and this study will also look at if that's safe and helpful. The study will include women aged 18-45 with a healthy pregnancy who can have the vaccine and antibody.

• The study will check babies' antibodies for one year to see how well the products work.
• Participants must agree to follow all study steps and give consent for themselves and their baby.
• Women with certain health issues or previous reactions to the products cannot join.