[59] Preterm Delivery Flashcards

1
Q

What % of deliveries in developed countries are preterm?

A

Up to 12%

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2
Q

What are the causes of preterm delivery?

A
  • Idiopathic
  • Intrauterine stretch
  • Intrauterine bleeding
  • Cervical weakness
  • Maternal medical conditions
  • Fetal problems
  • Intrauterine infection
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3
Q

What might cause intrauterine stretch leading to preterm delivery?

A
  • Multiple gestation
  • Polyhydramnois
  • Uterine abnormality
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4
Q

What might cause intrauterine bleeding leading to preterm delivery?

A
  • Abruption

- Antepartum haemorrhage

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5
Q

What maternal medical conditions might lead to pre-term delivery?

A
  • Pre-eclampsia
  • Chronic medical conditions
  • Urinary tract infection
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6
Q

What fetal problems might lead to preterm delivery?

A
  • IUGR

- Congenital malformations

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7
Q

What intrauterine infections may lead to preterm delivery?

A
  • Chorioamnionitis
  • Bacterial vaginosis
  • Preterm prolonged rupture of membranes
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8
Q

What are the risk factors for preterm delivery associated with?

A

Generally predispose the mother to infection or inflammation

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9
Q

What are the risk factors for preterm delivery?

A
  • 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
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10
Q

By how much does a previous preterm delivery increase the risk of another?

A

Twofold increased risk, increasing for each additional delivery

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11
Q

By how much does having a short inter-pregnancy interval of <6 months increase the risk of pre-term delivery?

A

More than doubles risk

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12
Q

What impact does maternal age have on pre-term delivery?

A

Increased risk of <20 or >35 years old

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13
Q

What effect does maternal nutrition have on the risk of pre-term delivery?

A

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

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14
Q

How does ethnicity affect the risk of pre-term births?

A

Higher in black mothers

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15
Q

What % of cases of preterm delivery are associated with multiple births?

A

15-20%

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16
Q

When is delivery recommended for monochorionic twins?

A

By 37 weeks

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17
Q

Give an example of when maternal health might increase the risk of pre-term delivery

A

Infections, either localised, e.g. ascending, or generalised, e.g. malaria

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18
Q

What are the strategies that can be used to prevent pre-term labour?

A
  • 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
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19
Q

What is the role of progesterone in the prevention of pre-term labour?

A

It is given prophylactically at 24 weeks to those at high risk of pre-term labour

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20
Q

What is the purpose of prophylactic progesterone in high-risk patients?

A

Reduces pre-term birth and perinatal morbidity in high risk patients

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21
Q

Give two examples of when progesterone prophylaxis might be given

A
  • Previous preterm birth

- Short cervix identified on ultrasound

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22
Q

Is progesterone prophylaxis given when there are multiple fetuses?

A

No

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23
Q

What is cervical cerclage?

A

Purse-string sutures to maintain closure of the maternal cervix

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24
Q

When might cervical cerclage be used?

A
  • Multiple pre-term brths
  • Mid-trimester fetal loss
  • Cervix is shortening
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25
Q

What alternative to cervical cerclage is being investigated?

A

Non-surgical ‘cervical pessary’

26
Q

How useful are interventions to prevent preterm birth?

A

The potential impact of these interventions to reduce the proportion of infants born preterm is relatively small

27
Q

What may be involved in the management of preterm delivery?

A
  • Antenatal corticosteroids
  • Tocolysis
  • Magnesium sulfate
28
Q

What is the main purpose of administering maternal corticosteroids before preterm birth?

A

Reduce the incidence of;

  • Respiratory distress syndrome
  • Intraventricular haemorrhage
  • Neonatal death
29
Q

By how much does the administration of maternal corticosteroids reduce the incidence of RDS?

A

44%

30
Q

By how much does the administration of maternal corticosteroids reduce the incidence of intraventricular haemorrhage?

A

46%

31
Q

By how much does the administration of maternal corticosteroids reduce the incidence of neonatal death?

A

31%

32
Q

What other things is the administration of maternal corticosteroids associated with the reduction of?

A
  • Necrotising enterocolitis
  • Need for respiratory support
  • Intensive care admission
  • Systemic infections in first 48 hours of life
33
Q

Who is offered maternal corticosteroids?

A
  • Mothers at risk of preterm birth up to 35 weeks gestation

- Women having an elective ceserean section prior to 39 weeks gestation

34
Q

Why are maternal corticosteroids offered to mothers having an elective c-section prior to 39 weeks gestation?

A

To reduce the risk of respiratory morbidity

35
Q

Describe the course of maternal corticosteroids given

A

Single course

36
Q

What does tocolysis do?

A

Suppress uterine contractions

37
Q

What is the purpose of tocolysis?

A

Widely used to suppress contractions to enable completion of a course of antenatal corticosteroids, or allow maternal transfer to perinatal centre

38
Q

When is magnesium sulfate offered?

A

When preterm delivery at 24-32 weeks is anticipated

39
Q

What is the purpose of magnesium sulfate in preterm delivery?

A

Reduce the risk of cerebral palsy

40
Q

How effective is magnesium sulfate in preventing cerebral palsy?

A

Several trials have shown a 30-40% reduction in cerebral palsy rates

41
Q

What % of pregnancies are affected by preterm premature rupture of membranes (PPROM)?

A

2-3%

42
Q

What % of pre-term deliveries are associated with PPROM?

A

25-30%

43
Q

Why does PPROM increase neonatal morbidity and mortality?

A

Due to prematurity, infection, and pulmonary hypoplasia

44
Q

What is a potential cause of PPROM?

A

Ascending maternal infection from the lower genital tract

45
Q

What supports the link between PPROM and ascending maternal infection from lower genital tract?

A

About 1/3 have positive amniotic fluid cultures

46
Q

What is involved in the management of PPROM?

A
  • Antibiotics
  • Delivery
  • Corticosteroids
47
Q

What is the role of antibiotics in PPROM?

A

Reduce chorioamnionitis and neonatal infection

48
Q

What does the decision to deliver or manage expectantly require in PPROM?

A

Balancing the risk of intrauterine infection compared with neonatal risks from prematurity

49
Q

What should be done if delivery before or at 34 weeks is required in PPROM?

A

Corticosteroids are given

50
Q

When is delivery usually indicated in PPROM?

A

Beyond 34 weeks

51
Q

What is the overall aim in preterm delivery?

A

Prolong pregnancy for as long as possible while ensuring the safety of the mother and fetus

52
Q

What is considered to be extreme preterm delivery?

A

<28 weeks

53
Q

What is the limit of viability?

A

22-26 weeks

54
Q

Who should the decision about timing of a preterm delivery at the limit of viability involve?

A
  • Obstetrician
  • Neonatologist
  • Parents
55
Q

What is decision making aided by when deciding timing of pre-term delivery at the limit of viability?

A

Detailed assessment of fetal wellbeing

56
Q

What is involved in a detailed assessment of fetal wellbeing?

A
  • Amniotic fluid volume
  • Fetal heart rate monitoring
  • Doppler studies
  • Fetal growth
  • Gestation
  • Predicted birthweight
57
Q

What epidemiological evidence can help inform decisions about delivery at the limit of viability?

A

Knowledge of outcomes at these early gestational ages, with national and international data

58
Q

Where should delivery of extremely pre-term babies take place?

A

At a perinatal center

59
Q

Why should the delivery of an extremely preterm baby take place at a perinatal centre?

A

To avoid subsequent transfer and separation of the infant and mother

60
Q

How does the health of infants born at 34-38 weeks compare to term infants?

A

They have an increase in respiratory morbidity and mortality, and increased length of stay in hospital compared to term infants. There are also higher neurodisability rates