This study would not add any new information

All pregnant women prenatally being followed up or admitted at Rambam HealthCare Campus, Haifa, Israel are potential participants in the study. If a patient is agreeable, the nurse/physician/research coordinator will obtain informed consent.

Once informed consent is obtained, the patient can be swabbed for GBS. The swabs will be obtained at the routine follow-up at the clinic at 30, 32 and 35 weeks' gestation.

If a patient is found to have a positive GBS culture at 35 weeks, she will receive antibiotic treatment during labour according to the protocol.

GBS swabs taken at delivery will be compared to previous swabs taken at an earlier gestational age in order to evaluate sensitivity, specificity, positive and negative predictive values of GBS swabs at each week of gestation and to determine the value of our primary hypothesis.

1. All pregnant women prenatally being followed up or admitted at Rambam HealthCare Campus, Haifa, Israel are potential participants in the study.
2. Most high-risk pregnant women have their routine follow ups every two weeks or less from the beginning of the third trimester (between 28 and 32 weeks' gestation).
3. The nurse/physician/research coordinator in the clinic will discuss the trial with those women. If a patient is agreeable, the nurse/physician/research coordinator will obtain informed consent.
4. Once informed consent is obtained, the patient can be swabbed for GBS.
5. The swabs will be obtained at the routine follow-up at the clinic at 30, 32 and 35 weeks' gestation. Then, they will be handed to the nurse/physician/research coordinator and transferred to the lab for analysis.
6. Swabs for GBS culture should be obtained, ideally before digital examination or use of lubricants, from both the lower vagina (vaginal introitus) and rectum (insert swab through the anal sphincter) to achieve maximum sensitivity. Either two swabs (one for each site) or a single swab can be used; one swab is more cost saving. The swabs will be obtained by the patient herself after appropriate instruction as studies have shown equivalent sensitivity between the healthcare provider and the patient herself20.
7. The swabs should be placed promptly into non-nutrient transport media (eg, Amies or Stuart's without charcoal) and transported at room temperature (in temperate climates) or refrigerated. The swabs are then transferred to a selective enrichment broth at a laboratory experienced in the isolation of GBS, incubated overnight at 37ºC, and subcultured onto blood agar plates. Cultures require 24 to 48 hours to show positive results. It takes 48 hours to definitively exclude GBS20.
8. The swabs will be kept for seven days, then will be removed by environmental services for their discard process.
9. A log of all patients who meet all inclusion criteria and agreed to participate in the trial will be maintained, recording the date and gestational age. GBS swab results will also be recorded. We will only reveal the results from the 35 weeks' screening to the main care provider of the patient as part of the common practice. We will not provide the other screening results, neither to the patient nor to their physician.
10. If a patient is found to have a positive GBS culture at 35 weeks, she will receive antibiotic treatment during labour according to the protocol.
11. GBS swabs taken at delivery will be compared to previous swabs taken at an earlier gestational age in order to evaluate sensitivity, specificity, positive and negative predictive values of GBS swabs at each week of gestation and to determine the value of our primary hypothesis.

Inclusion Criteria:

1. Pregnant women that are being followed up prenatally or admitted at Rambam HealthCare Campus, Haifa, Israel and are planning to deliver there.
2. Women at gestational age 300/7 or less.

Exclusion Criteria:

1. Age 18 and under.
2. Women with previous delivery of an infant affected by GBS disease.
3. Women with known bacteriuria in the current pregnancy.
4. Women whom are planning not to deliver at Rambam HealthCare Campus.
5. Women who will not consent to participate in the study.

We plan to conduct an open label prospective trial of all women with a singleton pregnancy which will be screened for GBS in four different time-points during their pregnancy, from 30 weeks' gestation up to delivery - 30, 32, 35 weeks' gestational age and at delivery.