Pre-term Birth

Question 1

Definition of Pre-term labour

Answer 1

The occurrence of regular uterine activity which produces either cervical effacement or dilation prior to 37 weeks gestation

Question 2

Incidence of Pre-term labour

Answer 2

6-7% in the UK –> 2-3% are Iatrogenic deliveries

1-2% are very pre-term (before 32 weeks)

Question 3

Mortality of pre-term birth

Answer 3

Perinatal mortality is dependent on gestational age
Exponentially increases with increasing prematurity
Also significant risk of lifelong disability

Question 4

Causes of preterm delivery (3,3,1)

Answer 4

Spontaneous labour --> 30-50%
Multiple pregnancy --> 10-30%
Premature ROM --> 5-40%
Hypertensive disorders --> 10%
IUGR --> 5%   APH --> 10%   Other --> 10%

Question 5

Risk factors for pre-term birth (3,4,2,4)

Answer 5

Age (>35), Primeip, IVF, maternal illness, ethnicity (black), weight gain, bacteriuria, HTN, smoking, multiple pregnancy, APH, fetal abnormalities,cervical incompetence

Question 6

Causes of Iatrogenic prematurity

Answer 6

When a patient is induced early on purpose
Pre-eclampsia (42.5%), Fetal distress (26.7%)
IGUR (10%), Abruption (6.7%), Fetal death (6.7%)
Other - placenta previa, maternal medical disorders

Question 7

Short term complications of prematurity (7)

Answer 7

Neonatal death, Morbidity due to precipitating factor
Respiratory distress syndrome, Cardiovascular (PDA etc), Immune failure, necrotising entercolitis, intraventricular haemorrhage, retinopathy of prematurity, birth trauma

Question 8

Long term complications of prematurity

Answer 8

Cerebral Palsy, Visual Problems, Poor respiratory function and ongoing breathing problems, poor cognitive and behavioural function

Question 9

How can we predict preterm labour?

Answer 9

Past Obstetric Hx, scoring systems (POH or social status), Using home uterine monitoring, Cervical Length (V. good indication if IL-6, IL8, fFN

Question 10

Cervicovaginal fetal fibronectin

Answer 10

An extracellular matrix protein produced by chorionic cells which is an adhesive binding the membranes to the uterine wall –> structurally altered at the end of pregnancy to make it less adhesive –>should not be present in the vagina between 22-36 weeks. only have negative predictive value

Question 11

Role of the cervix in preventing ascending infection

Answer 11

Acts as a barrier both physically and because mucus has antibacterial properties
breach of this barrier leads to inflammatory processes which further weaken the barrier and can lead to preterm labour

Question 12

Diagnosis of preterm labour

Answer 12

Regular contractions
pPROM
Cervical dilation or effacement

Question 13

Treatment of pre-term labour

Answer 13

Drugs to stop contractions (tocolysis): oxytocin receptor antagonists, Beta-mimics, NO donors, CCB, MgSO4, NSAIDs
Also steroids, antibiotics, progestogens, cervical cerclage

Question 14

Contraindications for tocolysis

Answer 14

Should not be used in cardiac disease or eclampsia
Intrauterine infection or death
APH or placenta previa

Question 15

Benefits of steroids

Answer 15

Reduce neonatal death
Respiratory distress syndrome
Necrotising enterocolitis
Periventricular haemorrhage

Question 16

Antibiotics in pre-term labour

Answer 16

Some evidence for giving augmentin or erythromycin in preterm labour with intact membranes
Treatment of BV in early labour is controversial
If SROM give Erythromycin (or penicillin if group B strep) as co-amox increases the risk of NEC while gentamicin is associated with auditory and vestibular damage.

Question 17

Cervical cerclage

Answer 17

A strong stitch being placed in and around the cervix between 12-14 weeks to prevent cervical incompetence and miscarriage

Question 18

Chorioamnionitis

Answer 18

Ascending infection - risk is increased by SROM and each vaginal exam. Will cause maternal fever, uterine tenderness if PROM. May have purulent discharge, if severe it can lead to vasculitis of umbilical vessels. Treat with delivery, broad spec abx for the mother. Increases the risk of cerebral palsy and periventricular leukomalacia.

Question 19

Braxton Hick contractions

Answer 19

Prodromal labour are sporadic uterine contractions which sometimes start around six weeks into a pregnancy. Not usually felt until the 2nd or 3rd trimester. Will be infrequent, irregular and only mild cramping (1-2mins). Can be improved by hydration, breathing, lying on the left side, urination or moving.