--- title: "Group B Strep Testing at Sutter Health" description: "Learn about Group B strep testing, a common prenatal screening in late pregnancy." url: "https://www.sutterhealth.org/health/group-b-strep" --- 1. [Home](https://www.sutterhealth.org/) / 2. [Health and wellness](https://www.sutterhealth.org/health) / 3. Group B Strep: What You Need to Know # Group B Strep: What You Need to Know Learn about this common prenatal test and how it's done. * * * August 19, 2025Medically reviewed by [Per L. Sandberg, M.D., FACOG](https://www.sutterhealth.org/find-provider/dr-per-l-sandberg-1046240705) During your last trimester, you'll still have [testing and screening](https://www.sutterhealth.org/services/prenatal-care-and-testing) to check your baby's development. Some tests, like Group B strep screening, help your care team know whether there are precautions they need to take during your [delivery](https://www.sutterhealth.org/services/labor-and-delivery). ![pregnant-woman-talking-with-doctor](https://edge.sitecorecloud.io/sutterhealt962c-sutterhealt8fce-production57cc-4860/media/Project/SutterHealth/SutterHealth/Images/people/women/pregnant-woman-talking-with-doctor.jpg) ## Routine Screening for Group B Strep (GBS) As you approach your due date, your care team will screen you for Group B strep (GBS). GBS is a bacterium that’s naturally present in your gastrointestinal (GI) tract and genital tract. Roughly 15-40% of patients are colonized with this bacteria. This means the bacteria can be present in your vagina or rectum. While GBS is harmless to you, it can cause serious infections in newborns.   ## When and How You’re Tested Your care team will screen for GBS between 35 and 37 weeks of [pregnancy.](https://www.sutterhealth.org/services/pregnancy-and-childbirth) The test involves your provider taking a swab of your vagina and rectum and then sending it to the lab for analysis. If you test positive, you’ll be given antibiotics during labor to significantly reduce the risk of passing GBS to your baby during vaginal delivery. GBS screening is a routine part of prenatal care. If you have questions about the test or treatment, [speak with your OB team](https://www.sutterhealth.org/patient-resources/my-health-online).  ## Explore related topics [Pregnancy](https://www.sutterhealth.org/health/articles?facets=%5B%7B%22i%22%3A%22c_healthTopics.name%22%2C%22v%22%3A%5B%22Pregnancy%22%5D%7D%2C%7B%22i%22%3A%22builtin.entityType%22%2C%22v%22%3A%5B%22Sutter+Health+Page%22%5D%7D%5D&limit=10&verticalKey=health-and-wellness)[Prenatal Tests](https://www.sutterhealth.org/health/articles?facets=%5B%7B%22i%22%3A%22c_healthTopics.name%22%2C%22v%22%3A%5B%22Prenatal+Tests%22%5D%7D%2C%7B%22i%22%3A%22builtin.entityType%22%2C%22v%22%3A%5B%22Sutter+Health+Page%22%5D%7D%5D&limit=10&verticalKey=health-and-wellness) ## Support at Every Step From conception to delivery and after, our [pregnancy and childbirth](https://www.sutterhealth.org/services/pregnancy-and-childbirth) providers put you first. [Schedule an Appointment](https://www.sutterhealth.org/find-provider-results?facets=%5B%7B%22i%22%3A%22c_providerSpecialties.specialty.name%22%2C%22v%22%3A%5B%22Infertility%22%2C%22Nurse+Midwife%22%2C%22Obstetrics+and+Gynecology%22%2C%22Reproductive+Endocrinology%22%5D%7D%5D&limit=10&verticalKey=healthcare_professionals) ## Meet our care team ![Per L. Sandberg, M.D., FACOG](http://a.mktgcdn.com/p/4K9H0GwE7hMhbI4to6T6jSaoV8tqfmu64gbh40b5XKU/480x480.png) [Per L. Sandberg, M.D., FACOG](https://www.sutterhealth.org/find-provider/dr-per-l-sandberg-1046240705) Maternal-Fetal Medicine ```json {"@context":"https://schema.org","@type":"MedicalOrganization","name":"Sutter Health","@id":"https://www.sutterhealth.org/#medicalorganization","url":"https://www.sutterhealth.org","logo":"https://www.sutterhealth.org/static/images/sutter-health-logo.svg","address":{"@type":"PostalAddress","streetAddress":"2200 River Plaza Drive","addressLocality":"Sacramento","addressRegion":"CA","postalCode":"95833","addressCountry":"US"},"areaServed":{"@type":"AdministrativeArea","name":"California"},"sameAs":["https://www.facebook.com/SutterHealth","https://www.instagram.com/sutterhealth/","https://x.com/SutterHealth","https://www.youtube.com/sutterhealth","https://www.linkedin.com/company/sutter-health","https://en.wikipedia.org/wiki/Sutter_Health"]} ``` ```json {"@context":"https://schema.org","@type":"WebPage","name":"Group B Strep Testing at Sutter Health","description":"Learn about Group B strep testing, a common prenatal screening in late pregnancy.","url":"https://www.sutterhealth.org/health/group-b-strep","breadcrumb":{"@id":"https://www.sutterhealth.org/health/group-b-strep#breadcrumblist"}} ``` ```json {"@context":"https://schema.org","headline":"Group B Strep: What You Need to Know","alternativeHeadline":"Group B Strep Testing at Sutter Health","description":"Learn about Group B strep testing, a common prenatal screening in late pregnancy.","datePublished":"2025-08-19T18:53:52Z","dateModified":"2026-10-23T16:01:42Z","publisher":{"@type":"MedicalOrganization","name":"Sutter Health","@id":"https://www.sutterhealth.org/#medicalorganization","url":"https://www.sutterhealth.org"},"image":{"@type":"ImageObject","url":"https://edge.sitecorecloud.io/sutterhealt962c-sutterhealt8fce-production57cc-4860/media/Project/SutterHealth/SutterHealth/Images/people/women/pregnant-woman-talking-with-doctor.jpg?h=4480&iar=0&w=6720","width":"6720","height":"4480","caption":"pregnant-woman-talking-with-doctor"},"@type":"MedicalWebPage","breadcrumb":{"@id":"https://www.sutterhealth.org/health/group-b-strep#breadcrumblist"},"reviewedBy":[{"@context":"https://schema.org","@type":"Person","name":"Per L. Sandberg, M.D., FACOG","url":"https://www.sutterhealth.org/find-provider/dr-per-l-sandberg-1046240705"}],"lastReviewed":"2026-10-23T16:01:42Z"} ``` ```json {"@context":"https://schema.org","@type":"BreadcrumbList","@id":"https://www.sutterhealth.org/health/group-b-strep#breadcrumblist","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://www.sutterhealth.org/"},{"@type":"ListItem","position":2,"name":"Health and wellness","item":"https://www.sutterhealth.org/health"},{"@type":"ListItem","position":3,"name":"Group B Strep: What You Need to Know"}]} ```