[59] Preterm Delivery Flashcards
What % of deliveries in developed countries are preterm?
Up to 12%
What are the causes of preterm delivery?
- Idiopathic
- Intrauterine stretch
- Intrauterine bleeding
- Cervical weakness
- Maternal medical conditions
- Fetal problems
- Intrauterine infection
What might cause intrauterine stretch leading to preterm delivery?
- Multiple gestation
- Polyhydramnois
- Uterine abnormality
What might cause intrauterine bleeding leading to preterm delivery?
- Abruption
- Antepartum haemorrhage
What maternal medical conditions might lead to pre-term delivery?
- Pre-eclampsia
- Chronic medical conditions
- Urinary tract infection
What fetal problems might lead to preterm delivery?
- IUGR
- Congenital malformations
What intrauterine infections may lead to preterm delivery?
- Chorioamnionitis
- Bacterial vaginosis
- Preterm prolonged rupture of membranes
What are the risk factors for preterm delivery associated with?
Generally predispose the mother to infection or inflammation
What are the risk factors for preterm delivery?
- Previous pre-term delivery
- Short interpregnancy interval of <6 months
- Maternal age
- Maternal nutrition
- Ethnicity
- Multiple births
- High levels of maternal psychological or social stress
- Smoking
- Substance misuse
- Maternal health
- Socio-economic deprivation
By how much does a previous preterm delivery increase the risk of another?
Twofold increased risk, increasing for each additional delivery
By how much does having a short inter-pregnancy interval of <6 months increase the risk of pre-term delivery?
More than doubles risk
What impact does maternal age have on pre-term delivery?
Increased risk of <20 or >35 years old
What effect does maternal nutrition have on the risk of pre-term delivery?
Low BMI increases the risk of spontaneous preterm birth.
Obese mothers are more likely to have preterm births for other indications, particularly pre-eclampsia and diabetes mellitus
How does ethnicity affect the risk of pre-term births?
Higher in black mothers
What % of cases of preterm delivery are associated with multiple births?
15-20%
When is delivery recommended for monochorionic twins?
By 37 weeks
Give an example of when maternal health might increase the risk of pre-term delivery
Infections, either localised, e.g. ascending, or generalised, e.g. malaria
What are the strategies that can be used to prevent pre-term labour?
- Progesterone
- Cervical cerclage
- Genital infection treatment
- Cessation of maternal smoking
- Reduction in multiple births by limiting embryo transfer in IVF treatment
- Reduction in elective preterm deliveries
What is the role of progesterone in the prevention of pre-term labour?
It is given prophylactically at 24 weeks to those at high risk of pre-term labour
What is the purpose of prophylactic progesterone in high-risk patients?
Reduces pre-term birth and perinatal morbidity in high risk patients
Give two examples of when progesterone prophylaxis might be given
- Previous preterm birth
- Short cervix identified on ultrasound
Is progesterone prophylaxis given when there are multiple fetuses?
No
What is cervical cerclage?
Purse-string sutures to maintain closure of the maternal cervix
When might cervical cerclage be used?
- Multiple pre-term brths
- Mid-trimester fetal loss
- Cervix is shortening