PB 130: Prediction and Prevention of Preterm Birth

Question 1

What is the leading cause of neonatal mortality in the US?

Answer 1

Preterm birth

Question 2

What is the strongest clinical risk factor for preterm birth?

Answer 2

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

Question 3

What are the overall risk factors for preterm birth?

Answer 3

• History of preterm birth (1.5 to 2-fold) - Short cervical length (defined as less than 25 mm, usually before 24 weeks, but up to 28 weeks) - Cervical surgery (LEEP, CKC) - Uterine instrumentation (D&C) - UTI - Genital tract infections - Periodontal disease - Low maternal pregnancy weight (BMI < 19.8) - Smoking - Substance abuse - Short interpregnancy interval (18-23 months)

Question 4

Screening: What is the most reliable and reproducible way to assess the length of the cervix and why?

Answer 4

Transvaginal cervical ultrasonography Unlike the trans abdominal approach, TVUS not affected by maternal obesity, position of cervix, and shadowing from the fetal presenting part

Question 5

What are two interventions for prevention of PTB in women with a singleton pregnancy without prior PTB?

Answer 5

Cerclage Progesterone

Question 6

What is the management of short cervix with no history of PTB?

Answer 6

If cervical length < 20 mm before or at 24 weeks, vaginal progesterone supplementation daily until 37 w

Question 7

Definition: Cervical Insufficiency

Answer 7

Inability of the cervix to maintain a pregnancy in the absence of the signs and symptoms of clinical contractions, or labor, or both the 2nd trimester

Question 8

Should a woman with a current singleton pregnancy without a history of preterm birth be screened for a risk of preterm birth?

Answer 8

In general, women in this clinical scenario are at a low risk of preterm birth. However, if second trimester transabdominal scanning of the lower uterine segment suggests that the cervix may be short or have some other abnormality, it is recommended that a subsequent TVUS exam be performed to better visualize the cervix and establish its length.

Question 9

What is the algorithm for the management of short cervical length in the 2nd trimester?

Answer 9

Question 10

Does cerclage placement or progesterone treatment decrease the risk of preterm birth in women with multiple gestations?

Answer 10

No

Cerclage may increase the risk of preterm birth in women with a twin pregnancy and ultrasonographically detected cervical length < 25 mm and is not recommended.

Question 11

Level A Recommendations and Conclusions

Answer 11