Prolonged pregnancy

Question 1

What is the definition of post term or prolonged pregnancy?

Answer 1

> /= 42 weeks

Question 2

What proportion of women labour post term?

Answer 2

roughly 10-15%

Question 3

What are the risks of prolonged pregnancy?

Answer 3

Increased risks of:

• Stillbirth
• Neonatal death
• death within 1st year of life

Due to increased risk of:

• Meconium aspiration.
• Macrosomia and larger babies resulting in:
  
  • Prolonged labour.
  • Cephalo-pelvic disproportion.
  • Shoulder dystocia.
  • Birth injury resulting in, for example, brachial plexus damage or cerebral palsy.
  • Neonatal acidaemia.
  • Low five-minute Apgar scores.
  • Neonatal encephalopathy.
  • Neonatal seizures.
• Features of intrauterine growth restriction (IUGR) due to placental insufficiency

Question 4

What is the evidence for timing of post dates induction?

Answer 4

Multicentre RCT published in BMJ in 2019 showed improved outcomes for perinatal morbidity and mortality when IOL at 41+0 versus expectant management until 42 weeks. 1.4% absolute risk reduction in perinatal adverse event. No different in maternal outcomes or risk of caesarean delivery.

Question 5

What management and advice should be given to women at risk of post-term?

Answer 5

• RCOG and NICE guidelines recommend that women should be offered induction after 41 weeks between 41+0 and 42+0 weeks to avoid the risks of post-term pregnancy, primarily increased intrauterine fetal death.
• Prior to formal induction of labour, women should be offered vaginal examination with membrane sweeping.
• If women choose not to have induction, this decision should be respected and from 42 weeks of pregnancy there should be increased monitoring with at least twice‑weekly cardiotocography and ultrasound estimation of maximum amniotic pool depth.
• Studies have also looked at the outcomes when labour is induced between 37 and 41 weeks of pregnancy and it appears to also reduce perinatal mortality week on week without increasing risk of operative delivery.[6]

Question 6

Risk factors for going post-term

Answer 6

Nulliparous
Age >30
Elevated BMI

Question 7

What percentage of post dates fetuses will have post maturity syndrome?

What does it involve?

Answer 7

20%

FGR 
Oligo 
meconium 
fetal distress 
dry, cracked skin 

Evidence of placental insufficiency

Question 8

Maternal risks of going post dates?

Answer 8

increase in labour dystocia
perineal trauma
CS
operative vaginal delivery

Question 9

How to reduce prolonged pregnancy?

Answer 9

• accurate dating in the first trimester
• Minimally invasive options: membrane sweeping (supported by evidence NNT 9-12), unprotected intercourse, acupuncture, nipple stimulation - not backed by evidence, Cochrane review showed insufficient evidence
• IOL between 41-42/40

Question 10

Data behind IOL at 41-42/40?

Answer 10

NNT to reduce 1 perinatal death is 440

RR IOL vs expectant mx was 0.31

RR mec aspiration 0.50