ACOG practice bulletin: preterm birth

Question 0

What is US preterm birth rate?

Answer 0

12%

Question 1

What is leading cause of neonatal mortality in the United States?

Answer 1

Preterm birth

Question 2

What are risk factors for preterm birth?

Answer 2

Prior preterm birth, including preterm twin birth
Short cervical length less than 25 mm up to 20 weeks
Smoking
Low BMI
Short interpregnancy interval
Data about prior cervical surgery or uterine instrumentation are mixed.
Vaginal bleeding, UTI, vaginal infection and periodontal disease are associated with increased risk but treatment has not been shown to decrease risk

Question 3

What is the interpregnancy interval with the lowest risk of adverse birth outcomes, including preterm birth?

Answer 3

18-23 months

Question 4

How should a pregnancy be managed in a woman with a prior spontaneous preterm delivery?

Answer 4

17 alpha-hydroxyprogesterone caproate 250 mg weekly injections from 16 until 36 weeks
Consider vaginal progesterone gel 90 mg daily from 20 weeks until 36 6/7 weeks

Cervical length ultrasound every two weeks starting at 16 until 23 weeks. If cervical length is between 25-29 mm frequency should be increased to weekly.

Question 5

When is prophylactic cerclage indicated?

Answer 5

For women with a prior spontaneous preterm birth less than 34 weeks now with a cervical length less than 25 mm before 24 weeks gestation

Question 6

How should women be advised about the effectiveness of prophylactic cerclage?

Answer 6

30% reduction in preterm birth less than 35 weeks and 36% reduction in composite perinatal mortality and morbidity

Question 7

What does ACOG say about universal screening for shortened cervix?

Answer 7

This strategy may be considered. Economic analysis suggest that ultrasound screening with treatment with vaginal progesterone is cost-effective.

Question 8

What cervical length and weeks of gestation was studied?

What medication and dosage or used?

How effective is this treatment?

Answer 8

Cervical length of less then 20 mm at up to 23 6/7 weeks

Vaginal progesterone gel 90 or 200 mg daily until 36 6/7 weeks

44-45% decrease in spontaneous preterm birth less than 34 weeks

Question 9

What is the role of cerclage for shortened cervix in women without a history of preterm birth?

Answer 9

Did not significantly decreased preterm birth rate even with cervical length of 15 mm or less

Question 10

What does ACOG say regarding progesterone or cerclage to prevent preterm birth in women with multiple gestation?

Answer 10

Neither reduces the risk of preterm birth so they are not recommended. Cerclage may increase the risk of preterm birth.