Signs of group B strep (GBS) infection in newborns include fever, difficulty breathing, poor feeding, lethargy, and seizures. In pregnant people, GBS often causes no symptoms, but it can lead to urinary tract infections, chorioamnionitis, or preterm labor. Routine prenatal screening between 35 and 37 weeks identifies carriers to prevent transmission during delivery.
Group B strep is a bacterium commonly found in the digestive, urinary, and reproductive tracts. It colonizes the rectum and vagina in about 25% of healthy adults, including pregnant people. The bacteria do not cause illness in carriers but can pass to a baby during vaginal birth. The infant's immature immune system cannot fight off the bacteria, leading to early-onset disease within the first 7 days of life.
Transmission occurs when the amniotic sac ruptures and the baby passes through the birth canal. The risk increases if labor begins before 37 weeks, if membranes have been broken for more than 18 hours, or if the mother develops a fever during labor. The bacteria can invade the bloodstream, lungs, or central nervous system, causing sepsis, pneumonia, or meningitis.
According to the Centers for Disease Control and Prevention (CDC), without treatment, about 1 in 200 infants exposed to GBS develops early-onset disease. With intrapartum antibiotic prophylaxis (IAP), that number drops to fewer than 1 in 1,000.
Newborns with early-onset GBS infection may show signs within hours of birth. These include respiratory distress such as grunting, flaring nostrils, or retractions. A fever above 38°C (100.4°F) is a red flag, though some infected babies remain normothermic. Poor feeding, irritability, or extreme lethargy can indicate systemic infection.
Neurological symptoms like jitteriness, seizures, or bulging fontanelles suggest meningitis. Blood cultures and lumbar punctures confirm diagnosis. The CDC recommends testing cerebrospinal fluid in any infant with suspected meningitis due to GBS.
A 2021 study published in *The Journal of Pediatrics* found that 60% of affected infants presented with respiratory symptoms, 30% had sepsis without clear focus, and 10% developed meningitis. Survival rates exceed 90% with prompt antibiotics, but long-term neurodevelopmental outcomes remain a concern in survivors of meningitis.
Group B strep colonization is asymptomatic in 95% of carriers. There is no pain, discharge, or odor associated with the presence of the bacteria. This lack of warning signs makes universal screening essential. Without testing, healthcare providers cannot identify who needs treatment.
The American College of Obstetricians and Gynecologists (ACOG) states that symptom-based screening is unreliable because many women with GBS have normal labor progress and uneventful deliveries. A single positive swab at 35-37 weeks gestation predicts risk with 90% accuracy.
One clinical trial comparing routine screening versus selective testing found that screening reduced early-onset GBS cases by 70%. The cost-effectiveness of universal screening was confirmed in a 2020 analysis by the National Institute of Child Health and Human Development.
Prenatal GBS screening involves a vaginal and rectal swab collected between 35 and 37 weeks. Swabs are cultured on selective media and incubated for 24-48 hours. A positive result indicates colonization, not active infection. The test does not diagnose disease-it identifies risk for transmission.
Results are reported as "positive" or "negative." A positive result means the person carries GBS and will receive intravenous penicillin during labor. Penicillin is the preferred agent due to high efficacy and low resistance rates. For those with a severe allergy, alternatives like cefazolin are used.
Table below summarizes standard screening protocols:
| Test Timing | Sample Site | Result Turnaround | Clinical Action |
|---|---|---|---|
| 35-37 weeks | Vaginal and rectal swab | 24-48 hours | IV penicillin during labor if positive |
| Before 35 weeks | Not recommended | N/A | Rescreen at 35-37 weeks |
| During labor | Not applicable | N/A | Start antibiotics if known carrier |
Many assume GBS is a sexually transmitted infection. It is not. GBS is part of the normal flora in the gastrointestinal and genitourinary tracts. It is not linked to hygiene, sexual activity, or lifestyle choices.
Another myth is that GBS causes stillbirth. While rare, GBS can contribute to intrauterine infection and preterm delivery, but it is not a direct cause of fetal demise. Stillbirths are more commonly associated with chromosomal abnormalities, placental insufficiency, or congenital anomalies.
Some parents believe that antibiotics during labor harm the baby. Evidence shows otherwise. A 2019 meta-analysis in *Obstetrics & Gynecology* found no increased risk of necrotizing enterocolitis, asthma, or allergic conditions in infants exposed to intrapartum penicillin.
In 2022, a 32-year-old woman at 36 weeks gestation had a routine GBS screen. Her swab grew Group B Streptococcus. She had no symptoms-no fever, no pelvic pain, no abnormal discharge. During labor, she developed a temperature of 38.2°C (100.8°F) and fetal heart rate decelerations. IV penicillin was administered. Her baby was born vaginally, weighed 3,200 grams, and showed no signs of infection. At 24 hours, the infant was healthy and discharged home.
This case illustrates how asymptomatic carriage leads to intervention based on screening. Without testing, the fever during labor might have been attributed to other causes, delaying treatment. The infant avoided infection due to timely antibiotic administration.
If a newborn shows signs of infection-fever, rapid breathing, poor feeding, or unusual sleepiness-seek medical attention immediately. Hospitalization and IV antibiotics are required. Early diagnosis improves outcomes.
For pregnant people, discuss GBS screening with your provider. If you've had a previous child with GBS disease, you'll be treated regardless of current test results. If you go into labor before the test is done, antibiotics are still given if risk factors are present.