Post-Term Pregnancy

Question 1

What is considered a post-term pregnancy?

Answer 1

one lasting 42 weeks gestation or more from the LMP

Question 2

What is the most common cause of post-term pregnancy?

Answer 2

inaccurate estimation of gestational age

Question 3

What are the “risk factors” for inaccurate estimation of gestational age?

Answer 3

• women with irregular menses and thus inconsistent ovulation
• women who seek prenatal care later in pregnancy
• women with delayed ovulation secondary to recently discontinued oral contraceptives

Question 4

What are risk factors for post-term pregnancy?

Answer 4

• prior post-term pregnancy
• maternal obesity, nulliparity, and post-term delivery of the mother
• risk factors associated with inaccurate estimation of gestational age: irregular menses, late to seek prenatal care, recently discontinued oral contraceptives

Question 5

Post-Term Pregnancy

Answer 5

• a pregnancy lasting 42 weeks gestation or more
• risk factors include prior, maternal obesity, nulliparity, post-term delivery of mother, irregular menses, and recently discontinued oral contraceptives
• the most common cause is inaccurate estimation of gestational age; other causes include anencephaly, fetal adrenal hypoplasia, and placental sulfatase deficiency
• may be complicated by macrosomia, shoulder dystocia, meconium aspiration syndrome, dysmaturity syndrome, and oligohydramnios

Question 6

What are the major complications of post-term pregnancy?

Answer 6

• macrosomia
• shoulder dystocia
• meconium aspiration syndrome
• dysmaturity syndrome
• oligohydramnios

Question 7

What complications are associated with macrosomia?

Answer 7

• shoulder dystocia
• clavicular fracture
• brachial plexus injury
• maternal perineal and vaginal lacerations
• postpartum hemorrhage

Question 8

How does pregnancy length affect the risk for meconium aspiration syndrome?

Answer 8

as pregnancy lengthens, the risk of MAS increases

Question 9

Dysmaturity Syndrome

Answer 9

• an infant with characteristics resembling chronic growth restriction
• associated with post-term labor and an aging placenta, no longer able to adequately support the fetus
• increases the risk for meconium aspiration, umbilical cord compression due to oligohydramnios, and short-term complications like hypoglycemia, seizures, and respiratory insufficiency

Question 10

How do we define oligohydramnios?

Answer 10

as an amniotic fluid index less than 5 cm defined by the total measurements of the largest vertical pockets of fluid in each of the quadrants

Question 11

When should ultrasound dating be used in place of LMP?

Answer 11

if dating by ultrasound performed at 14-16 weeks differs by more than 7 days or if dating by US performed at 16-22 days differs by more than 10 days

Question 12

How is post-term labor typically managed?

Answer 12

with induction at 41 weeks gestation