#130 Prediction and Prevention of Preterm Birth

Question 1

What percentage of preterm births are preceded by preterm labor?

Answer 1

50%

Question 2

What is the overall preterm birth rate?

Answer 2

~12%

Question 3

At what gestational age range are risks of perinatal, neonatal, and infant morbidity and mortality lowest?

Answer 3

Infants born between 39w0d and 40w6d.

Question 4

What is one of the strongest clinical risk factors for preterm birth?

Answer 4

Prior preterm birth (1.5-fold to 2-fold increased risk in subsequent pregnancy)

Question 5

What is the definition of short cervix?

Answer 5

Cervical length less than 25mm usually before 24wks, but up to 28wks in some series

Question 6

What are behavioral risk factors for preterm birth?

Answer 6

Low maternal prepregnancy weight, smoking, substance abuse, short pregnancy interval

Question 7

What interpregnancy interval is associated lowest risk of adverse birth outcomes including preterm birth?

Answer 7

18-23 months

Question 8

Does cervical funneling increase the risk of preterm delivery with a shortened cervical length?

Answer 8

No, not as an independent finding

Question 9

Was is/was the criteria for progesterone supplementation (Makena)? When should it be started?

Answer 9

Singleton gestation and prior spontaneous preterm singleton birth. Started at 16-24wks.

Question 10

When do you start cervical length screening in patients with a previous preterm delivery?

Answer 10

At 16wks, q2wks.

Question 11

Up to what gestational age can you place a cerclage?

Answer 11

24wks gestation

Question 12

What are the criteria for an ultrasound indicated cerclage?

Answer 12

Hx of prior preterm birth (<34wks) and short cervix (<25mm before 24wks)

Question 13

Does cerclage combined with progesterone decrease risk of preterm birth?

Answer 13

Insufficient evidence exists

Question 14

If someone on IM progesterone for hx of prior spontaneous preterm birth develops short cervix do you switch or add vaginal progesterone?

Answer 14

No evidence to suggest that switching is beneficial

Question 15

Is there available screening for risk of preterm delivery in low risk women (no prior preterm)?

Answer 15

Cervical length screening

Question 16

At what cervical length would you treat a women with no hx of prior preterm delivery? With what?

Answer 16

Vaginal progesterone (200mg daily) or 90mg vaginal progesterone gel for cervical length less than or equal to 20mm before or at 24wks.

Question 17

What interventions are supported for decreasing risk of preterm birth for multiple gestation with short cervix?

Answer 17

No interventions have been shown to improve outcomes

Question 18

Vaginal progesterone used for asymptomatic women with cervical length of 15mm or less at 20-25wks decreases spontaneous preterm birth prior to 34 weeks by what %tage?

Answer 18

44%

Question 19

What is the role of cervical pessary with short cervix?

Answer 19

One small trial (n=385) showed decreased rate of spontaneous delivery in women with incidentally diagnosed short cervix (<25mm at 18-22wks) (6% vs 27%)

Question 20

What is the role of cerclage in twin pregnancy?

Answer 20

Cerclage increases the risk of preterm delivery in twin gestations

Question 21

Does progesterone supplementation decrease the incidence of preterm birth in twin or triplet gestation?

Answer 21

No, not recommended as an intervention