Nursing care
Group B Streptococcus nursing care: what to assess and what to do first
Written and reviewed by Dana Whitfield, RN, MSN · 6 min read · Updated September 2026
Short answer
Group B Streptococcus nursing care centres on universal screening at 36 weeks gestation and, for colonised patients, intrapartum antibiotic prophylaxis started at least four hours before delivery. The goal is preventing vertical transmission to the neonate, since GBS passes during labour through the vaginal canal or ruptured membranes and can cause serious early-onset neonatal infection.
The pathophysiology in one pass
Group B Streptococcus, Streptococcus agalactiae, colonises the vagina and rectum of a significant proportion of pregnant women without causing symptoms in the mother. Colonisation itself is not an infection and requires no treatment outside of labour. The clinical concern is vertical transmission: during labour and delivery, or after membrane rupture, the neonate can be exposed to GBS as it passes through the birth canal or as bacteria ascend through ruptured membranes.
In the neonate, GBS causes early-onset disease within the first week of life, typically the first 24 to 48 hours, presenting as sepsis, pneumonia, or meningitis. Preterm and low-birth-weight infants carry higher risk of severe outcomes. Late-onset disease, occurring after the first week, is less reliably prevented by intrapartum measures and may arise from other transmission routes. This distinction matters because intrapartum antibiotic prophylaxis is effective specifically against early-onset disease, not late-onset.
Assessment findings that matter
Maternal GBS colonisation itself produces no reliable signs or symptoms, so assessment leans on screening history rather than physical exam. Nurses confirm and document the 36-week rectovaginal culture result, noting that results are considered valid for about five weeks; a culture done too early in relation to a late delivery may need repeating or treating empirically. Review the chart for GBS bacteriuria at any point in the current pregnancy, since a positive urine culture for GBS at any gestational age mandates intrapartum prophylaxis regardless of the 36-week swab result.
In labour, assess and document risk factors that trigger empiric antibiotics when GBS status is unknown: rupture of membranes 18 hours or longer, maternal fever of 38°C or higher, and preterm labour before 37 weeks. In the neonate, assessment shifts to signs of early-onset sepsis: respiratory distress, temperature instability, poor feeding, lethargy, and tachycardia or hypotension. Any of these in the first 48 hours in an infant born to a GBS-positive or untreated mother warrants prompt escalation.
What the exam asks about this
NCLEX-style items on GBS frequently test the timing rule. Screened at 36 weeks, and intrapartum antibiotics at least four hours before delivery, is the fact the question is usually built around; a scenario describing antibiotics started only two hours before delivery is testing whether you recognise that prophylaxis is considered inadequate and the newborn needs closer observation, not that the mother should simply be reassured.
Questions also test the difference between colonisation and infection: expect distractors suggesting a GBS-positive mother needs antepartum treatment or isolation precautions, when in fact no treatment is given until labour begins. Another pattern tests knowledge of penicillin allergy management; a GBS-positive patient with a penicillin allergy needs an alternative such as cefazolin, clindamycin, or vancomycin depending on allergy severity and susceptibility, and picking plain penicillin regardless of a documented severe allergy is a common wrong answer. Finally, expect scenarios where membrane status or fever substitutes for a formal culture result, since these risk factors independently trigger prophylaxis.
Nursing interventions in priority order
First, verify and document GBS status on admission to labour and delivery, checking the 36-week culture result, any GBS bacteriuria history, and prior infant affected by GBS disease, since any of these independently indicates prophylaxis. Second, initiate intrapartum antibiotics as soon as GBS-positive status or risk factors are confirmed, prioritising this over lower-urgency admission tasks because timing to delivery is the variable that determines effectiveness.
Third, monitor labour progress and estimate time to delivery, since the four-hour rule shapes decisions about induction pacing where clinically appropriate and informs the neonatal team about adequacy of prophylaxis. Fourth, communicate prophylaxis status and adequacy clearly at handoff to the neonatal team; a baby born after less than four hours of maternal antibiotics is generally managed with a period of closer clinical observation rather than automatic antibiotic treatment. Fifth, educate the postpartum patient that GBS colonisation is common, not a reflection of hygiene or a permanent diagnosis, and does not affect future pregnancies unless she is positive again.
Medications and monitoring
Intravenous penicillin G is the first-line intrapartum antibiotic, chosen for its narrow spectrum and low resistance profile against GBS. Ampicillin is an accepted alternative. For patients with a low-risk penicillin allergy, cefazolin is typically used; for high-risk or anaphylactic penicillin allergy, clindamycin is used if the isolate is confirmed susceptible, or vancomycin if clindamycin resistance is present or susceptibility is unknown.
Monitor the mother for the standard signs of an infusion or allergic reaction with any first dose, and continue dosing at the appropriate interval through labour until delivery. Monitor the neonate according to the adequacy of prophylaxis: an infant born to a mother who received an appropriate antibiotic for four or more hours before delivery generally needs only routine observation for 24 to 48 hours, while an infant with inadequate prophylaxis, or born to a GBS-positive mother who received no antibiotics, needs a closer observation protocol with vital sign monitoring at defined intervals, since early-onset sepsis can present rapidly.
When to escalate
Escalate immediately if a neonate born to a GBS-positive or unknown-status mother develops respiratory distress, grunting, temperature instability, lethargy, poor feeding, or signs of hemodynamic compromise in the first 48 hours; these findings warrant prompt evaluation for sepsis, including blood cultures and empiric antibiotics, rather than a watch-and-wait approach. Escalate any maternal fever intrapartum, since it may indicate chorioamnionitis, a separate and more urgent concern that changes the antibiotic regimen and delivery planning.
Escalate when antibiotics are started with clearly inadequate time before an imminent delivery, so the neonatal team can plan enhanced observation in advance rather than reacting after birth. Also escalate any known or suspected penicillin allergy before antibiotics are ordered, so the correct alternative agent is selected the first time; delays here directly affect whether prophylaxis is adequate by the time delivery occurs.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our maternity and newborn practice questions are the closest set to what this page covers.
Common questions
When is the GBS screening test done in pregnancy?
A rectovaginal swab is collected at 35 to 37 weeks gestation, commonly referred to as the 36-week screen. Results guide the intrapartum antibiotic decision and remain valid for about five weeks.
What counts as adequate intrapartum antibiotic prophylaxis for GBS?
Adequate prophylaxis means an appropriate IV antibiotic, usually penicillin, given at least four hours before delivery. Less than four hours is considered inadequate and typically prompts closer newborn observation rather than automatic treatment.
Does a GBS-positive mother need treatment before labour starts?
No. GBS colonisation does not require antepartum treatment because antibiotics given days or weeks before labour do not reliably clear colonisation by the time of delivery. Treatment is timed specifically to labour.
What if a GBS-positive mother is allergic to penicillin?
The alternative depends on allergy severity and, where available, susceptibility testing: cefazolin for a low-risk allergy, or clindamycin or vancomycin for a high-risk or anaphylactic allergy. This should be flagged and confirmed before labour whenever possible.
Is a caesarean birth without labour still an indication for GBS prophylaxis?
Generally no, if membranes are intact and labour has not begun, since the main transmission route through the birth canal or ruptured membranes has not been engaged. Practice can vary by institution, so confirm local protocol.