Preterm labor
General Preterm Labor and Birth
Q: What is preterm labor?
A: Preterm labor is the onset of regular uterine contractions that cause cervical effacement and/or dilation before 37 weeks of gestation.
Q: At what gestational age is a birth considered preterm?
A: A birth is considered preterm if it occurs between 20 weeks and 36 weeks + 6 days of gestation.
Q: What is late preterm birth?
A: Late preterm birth occurs between 34 weeks and 36 weeks + 6 days of gestation, accounting for 75% of preterm births in the U.S.
Risk Factors
Q: What are some demographic risk factors for preterm labor?
A: African-American race, low socioeconomic status, limited education, and late entry into prenatal care.
Q: How does BMI affect preterm labor risk?
A: A BMI less than 19.6 or greater than 30 increases the risk of preterm labor.
Q: Name a lifestyle-related risk factor for preterm labor.
A: Smoking or substance abuse.
Q: What pregnancy-related conditions can increase the risk of preterm labor?
A: Previous preterm birth, bleeding of uncertain origin, multifetal gestation, or uterine anomalies.
Predictors and Prevention
Q: What is fetal fibronectin (fFn), and how is it used?
A: Fetal fibronectin is a glue-like glycoprotein found in cervical/vaginal secretions. Its presence between the second and third trimesters may indicate inflammation and preterm labor risk. A negative test predicts with 98% accuracy that labor will not occur soon.
Q: What is considered a short cervical length, and how is it measured?
A: A cervical length of less than 2.5 cm, measured via ultrasound, is considered short and indicates a higher risk of preterm labor.
Q: What are some strategies to prevent preterm birth?
A: Preconception counseling, progesterone supplementation (vaginal or injectable), smoking cessation, and maintaining a healthy weight.
Medications for Preterm Labor
Q: What is the purpose of tocolytics?
A: Tocolytics are medications used to delay labor temporarily, giving time for interventions like corticosteroids or transfer to a specialized facility.
Q: How does magnesium sulfate help in preterm labor?
A: Magnesium sulfate relaxes the uterus and provides neuroprotection for the baby. It is used short-term, often less than 48 hours.
Q: What is the antidote for magnesium sulfate toxicity?
A: Calcium gluconate.
Q: How does nifedipine (Procardia) work in preterm labor?
A: Nifedipine is a calcium channel blocker that relaxes the smooth muscles of the uterus.
Q: What are the side effects of terbutaline (Brethine)?
A: Side effects include tachycardia, palpitations, chest discomfort, tremors, and nausea.
Fetal Interventions
Q: What is the role of betamethasone in preterm labor?
A: Betamethasone is a corticosteroid that helps mature the baby's lungs by stimulating surfactant production, reducing the risk of respiratory distress syndrome (RDS).
Q: At what gestational age is betamethasone most commonly administered?
A: Between 24 and 36 weeks of gestation.
Cervical Insufficiency
Q: What is cervical insufficiency?
A: Cervical insufficiency is the painless dilation of the cervix in the second trimester, leading to preterm birth without uterine contractions.
Q: How is cervical insufficiency treated?
A: A cerclage, which is a stitch placed around the cervix to reinforce it, is used to treat cervical insufficiency.
Preterm Premature Rupture of Membranes (PPROM)
Q: What is PPROM?
A: Preterm premature rupture of membranes (PPROM) is when the amniotic sac ruptures before 37 weeks of gestation.
Q: What is the most common complication of PPROM?
A: Chorioamnionitis, a bacterial infection of the amniotic cavity, occurs in up to 25% of cases.
Q: How is PPROM managed?
A: Management includes hospitalization, monitoring for infection, corticosteroids for fetal lung maturity, and antibiotics to prevent infection.
Multifetal Pregnancy
Q: What are the risks associated with multifetal pregnancies?
A: Risks include anemia, preterm labor, placenta previa, placental abruption, and congenital malformations (in monozygotic twins).
Q: Why do women over 35 have a higher chance of multifetal pregnancies?
A: Due to age-related fertility treatments and increased use of assisted reproductive technologies (ART).
Hyperemesis Gravidarum
Q: What is hyperemesis gravidarum?
A: Hyperemesis gravidarum is severe, excessive vomiting during pregnancy that leads to weight loss, dehydration, electrolyte imbalance, and nutritional deficiencies.
Q: How is hyperemesis gravidarum treated?
A: Treatment includes IV fluids, antiemetics, vitamin B6, and Unisom, as well as monitoring weight, electrolytes, and hydration.
Activity Restrictions
Q: Is bedrest recommended for preterm labor?
A: There is no current evidence to support bedrest as a prevention method for preterm labor, and it may cause physical and emotional strain.