GBS is present in the bowel flora of 20–40% of adults (this is called ‘colonisation’). People who are colonised are called
‘carriers’. This includes pregnant women (there is no evidence that its carriage rate is specifically affected by pregnancy).

Antenatal treatment for vaginal or rectal colonisation does not reduce the likelihood of GBS colonisation at the time of delivery and so is not indicated in this situation.

IAP should be offered to GBS-colonised women

Systemic chemotherapy is contraindicated in the first trimester because of a high rate of fetal
abnormality,but is safe from the second trimester.

If the placenta is thought to be low lying (less than 20 mm from the internal os) or praevia
(covering the os) at the routine fetal anomaly scan, a follow-up ultrasound examination
including a TVS is recommended at 32 weeks of gestation to diagnose persistent low-lying
placenta and/or placenta praevia.

Use of TVS- to accurately see the placental edge. Also, cervical length is a predictor of antepartum bleeding and emergency preterm caesarean section in placenta praevia. Women with a cervical length of less than 31 mm have a 16 times higher risk of emergency
caesarean section due to massive haemorrhage.

Risk of anal sphincter injury in women undergoing VBAC is 5%.

Birthweight is the strongest predictor of anal sphincter injury in women undergoing VBAC.

Conception during tamoxifen therapy should be avoided because
of potential teratogenicity, and a ‘washout period’ of 2–3 months is advised

Planned VBAC is contraindicated in women with previous uterine rupture or classical caesarean scar.

Women who have had two or more prior lower segment caesarean deliveries may be offered VBAC after counselling by a senior obstetrician. This should include the risk of uterine rupture and maternal morbidity, and the individual likelihood of successful VBAC.

This is GBS bacteruria. GBS bacteriuria is associated with a higher risk of chorioamnionitis and neonatal disease. Women with GBS bacteriuria should be offered IAP.

Women with GBS urinary tract infection (growth of greater than 10^5 cfu/ml) during pregnancy should receive appropriate treatment at the time of diagnosis as well as IAP. 

After collection, swabs should be placed in a non-nutrient transport medium, such as Amies or Stuart. Specimens should be transported and processed as soon as possible. If processing is delayed, specimens should be refrigerated. When testing for GBS, the lab should be specifically informed that the swab is for GBS testing.

Bonus info- There is at least one more condition in which the delivery should be delayed for some time after appearance of the condition- Chickenpox ! In varicella rash- planned delivery should normally be avoided for at least 7 days after the onset of the maternal rash to allow for the passive transfer of antibodies from mother to child.

It should be done at 32–34 weeks of gestation for women with twins.

The recommended time of testing is 3–5 weeks prior to the anticipated delivery date- therefore  35–37 weeks of gestation in singleton pregnancies with no risk factors for preterm delivery.

- For pregnancies at more than 16 weeks of gestation the term low-lying placenta should be used when the placental edge is less than 20 mm from the internal os on transabdominal or transvaginal scanning (TVS).

If the distance between the internal os and the placental edge is 20 mm or more on TVS, the placental location should be recorded as normal and managed as per routine

• The term placenta praevia should be used when the placenta lies directly over the internal os.