1.1. Background
Group B streptococci (streptococcus agalactiae) (GBS) are gram-positive bacteria commonly found in human gastrointestinal and genital tracts. GBS colonization is found in around 13% of pregnant women, though colonization rates may be higher in certain subgroups (3, 4). While GBS colonization is usually harmless among the general population, colonization during pregnancy increases the risk of maternal peripartum infections, preterm premature rupture of membranes, and preterm birth (5). The newborn can become infected following aspiration of infected amniotic fluid or contact with the bacteria during birth (5). Around half (40–50%) of babies born to colonized mothers will become colonized with GBS (6).
GBS infection leads to substantial perinatal morbidity and mortality. It is a leading cause of serious neonatal infection, affecting over 390 000 newborns per year (7). GBS infection was linked to an estimated 46 200 stillbirths and up to 91 900 infant deaths in the year 2020 (7). In addition, 37 100 children who recovered from invasive GBS infection were predicted to develop moderate or severe neurodevelopmental impairment (7). Early onset GBS (EOGBS) disease is the leading cause of early-onset neonatal sepsis (8). It is defined by presence of GBS in the newborn’s blood, cerebrospinal fluid or other usually sterile site within the first seven days following birth (9).
EOGBS can be prevented through intrapartum antibiotic prophylaxis (IAP) administered to pregnant women prior to birth (10). As part of its 2015 recommendations for the prevention and treatment of maternal peripartum infections (1), the World Health Organization (WHO) currently recommends IAP for women with GBS colonization for the prevention of early neonatal GBS infection. However, this recommendation does not provide guidance on approaches to determine the presence of GBS colonization, or the risk of early onset GBS disease based on other factors.
Given the adverse effects of EOGBS disease for newborns and families, as well as ongoing debate about – and variation in – screening practices (11, 12), there is a need to identify whether maternal screening strategies are effective in preventing EOGBS disease and improving maternal and neonatal outcomes. Maternal screening strategies assess risk for EOGBS infection either by presence of maternal GBS colonization or by maternal risk factors known to be associated with EOGBS disease. In this context, maternal screening strategies for EOGBS risk serve to identify women eligible for IAP, which can then prevent the transmission of GBS from the women to her newborn. It is important to note that EOGBS can occur with a negative maternal GBS culture (13).
Potential approaches for assessing EOGBS risk in women (and thus determining eligibility for IAP) include: (i) universal screening: where all women undergo antepartum culture-based screening (rectovaginal swabbing is used to obtain a sample) and IAP is administered to those who have evidence of GBS colonization; (ii) risk factor-based screening: where IAP is administered to pregnant women when one or more risk-factors for EOGBS infection are present (no swabbing for GBS colonization is carried out); (iii) a combined strategy of universal and risk-based screening; and (iv) no specific screening strategy, with IAP administered based on individual assessment. Risk-factors typically considered in the risk-based approach include maternal fever, rupture of membranes, bacteriuria, and previous child with EOGBS (13), though these may vary across settings. Regardless of the strategy, most pregnant women with known GBS bacteriuria (for example due to urine testing for urinary tract infection) or a previous child affected by an EOGBS infection will have IAP.
When considering the most effective method for reduction of EOGBS disease, contextual information such as local GBS prevalence and country income (1), rising antimicrobial resistance (14), and possible relationships between early antibiotic exposure and altered gut microbiome, asthma and obesity (15, 16) should be taken into account.
1.2. Rationale and objectives
WHO has established a process for prioritizing the development of maternal and perinatal health recommendations, whereby an international group of independent experts – the Executive Guideline Steering Group (GSG) – oversees a systematic prioritization of MPH recommendations in most urgent need of development (17, 18). The Executive GSG prioritized development of the WHO recommendation on screening of pregnant women for intrapartum antibiotic prophylaxis for the prevention of early onset Group B streptococcus disease in newborns to complement the existing WHO recommendation supporting the provision of intrapartum antibiotic prophylaxis for women with GBS colonization (1).
This recommendation was developed in accordance with the standards and procedures in the WHO handbook for guideline development, including synthesis of available research evidence, use of the Grading of Recommendations Assessment, Development and Evaluation (GRADE)1 and GRADE Confidence in the Evidence from Reviews of Qualitative Research (GRADE-CerQUAL)2 methodologies, and formulation of recommendations by a Guideline Development Group (GDG) composed of international experts and stakeholders (19). The primary aim of this recommendation is to improve the quality of care and outcomes for women and newborns, as they relate to the prevention of EOGBS disease in newborns.
1.3. Target audience
The primary audience includes health professionals who are responsible for developing national and local health-care guidelines and protocols (particularly those related to the prevention and treatment of peripartum infections) and those involved in the provision of care to women during labour and childbirth, including midwives, nurses, general medical practitioners and obstetricians, as well as managers of maternal and child health programmes, and relevant staff in ministries of health and training institutions, in all settings.
This recommendation will also be of interest to women giving birth, as well as members of professional societies involved in the care of pregnant women, staff of nongovernmental organizations concerned with promoting people-centred maternal care, and implementers of maternal and perinatal health programmes.
The term “woman” includes individuals who have given birth, even if they may not identify as a woman or as a mother. It is recognized that some individuals who have given birth identify as gender diverse.
1.4. Scope of the recommendation
This recommendation specifically addresses GBS screening strategies to determine candidacy for intrapartum antibiotic prophylaxis in women at or near term. Vaccination, intrapartum rapid testing, and other methods to reduce GBS infection which are currently not readily implementable in health-care settings are beyond the scope of the recommendation.
Two questions guided the development of the recommendation. Framed using the Population (P), Intervention (I), Comparison (C), Outcome (O) (PICO) format, these questions were:
Among pregnant women at or near term (P) does a screening strategy for intrapartum antibiotic prophylaxis for the prevention of early onset GBS disease in newborns (I) compared with no screening strategy (C) improve maternal and neonatal outcomes (O)?
Among pregnant women at or near term (P) does a screening strategy for intrapartum antibiotic prophylaxis for the prevention of early onset GBS disease in newborns (I) compared with another screening strategy (C) improve maternal and neonatal outcomes (O)?
1.5. Persons affected by the recommendation
The population affected by this recommendation includes all pregnant women at or near term and their newborns.
