Preterm Birth Flashcards
What is considered early preterm?
33 6/7 weeks or earlier
What is considered late preterm?
34 to 36 weeks
What is considered early term?
37 to 38 6/7 weeks
What is considered full term?
39 to 40 6/7 weeks
What is the ‘39-week rule’?
Adverse neonatal sequelae may result from elective delivery prior to 39 weeks
What are the fetal sizes by gestational age?
SGA (<10% BW), AGA (10th-90th%), LGA (>90%)
What are the common causes of preterm labor?
Uterine distention, maternal-fetal stress, cervical dysfunction, infection
What are the risk factors for uterine distention?
Multifetal pregnancy, hydramnios (more than 2L of amniotic fluid)
What maternal hormones play a role in preterm labor due to stress?
Corticotropin-releasing hormones causing premature rise in estrogen
What are common types of infections that cause preterm labor?
Transplacental, retrograde flow, ascending infection from vagina and cervix
What is Preterm Premature Rupture of Membranes (PPROM)?
A condition where the amniotic sac breaks before labor begins, leading to preterm birth.
What are the major predisposing factors for PPROM?
Oxidative stress, intrauterine infection, premature cellular senescence
How does multifetal pregnancy affect preterm labor?
Uterine distension leads to premature activation of contraction-associated proteins (CAPs)
What are lifestyle factors that contribute to preterm birth?
Age, poverty, short stature, extremes of maternal weight, smoking, drug use
What genetic factors contribute to preterm birth?
Immunoregulatory genes can potentiate chorioamnionitis and cause recurrent preterm birth
What is the most important risk factor for preterm labor?
Prior preterm birth
How do short intervals between pregnancies affect preterm birth?
Intervals <18 months increase the likelihood of preterm birth
What is the role of progesterone therapy in preventing preterm birth?
Progesterone helps maintain uterine quiescence and prevents early contractions
What is the role of cervical cerclage in preventing preterm birth?
It supports the cervix in women with cervical insufficiency or short cervix
What is the guideline for corticosteroid use to accelerate fetal lung maturity?
Recommended for women with ruptured membranes between 24-34 weeks
What are the key interventions for managing PPROM in pregnancies over 34 weeks?
Plan delivery, group B streptococcal prophylaxis, single corticosteroid course
What antimicrobial therapy benefits exist in managing preterm labor?
Fewer women develop chorioamnionitis, fewer newborns develop sepsis
What are the risk factors for clinical chorioamnionitis?
Maternal fever, low parity, multiple digital exams, use of internal uterine monitors
What are the tocolytic agents used to delay labor?
Beta-adrenergic receptor drugs, magnesium sulfate, prostaglandin inhibitors
What are the side effects of beta-adrenergic receptor drugs?
Pulmonary edema, sodium and water retention
How is magnesium sulfate used in preterm labor management?
Given as a loading dose of 4g, followed by continuous infusion to delay labor
What are calcium channel blockers used for in preterm labor?
Inhibit calcium entry in cells, reduce contractions (e.g., nifedipine)
What is the function of fetal fibronectin?
It plays a role in intercellular adhesion during implantation and maintains placental adherence to the uterine wall.
What does a positive fetal fibronectin test indicate?
It may indicate impending preterm labor if levels exceed 50 ng/mL in cervico-vaginal secretions.
How is cervical length measured and what is considered short?
Cervical length is measured via transvaginal ultrasound; a short cervix is < 3cm.
What is the purpose of cervical cerclage?
It is a surgical procedure to prevent premature dilation of the cervix in women at risk of preterm birth.
What is the rationale for using corticosteroids in preterm birth management?
Corticosteroids accelerate fetal lung maturity and reduce the risk of respiratory distress syndrome (RDS).
What are the symptoms of true preterm labor?
Regular contractions before 37 weeks, associated with cervical change.
What is the role of amniocentesis in managing preterm labor?
It can help detect intrauterine infection but is not routinely used in preterm birth management.
What is magnesium sulfate used for in preterm labor?
It provides neuroprotection and may reduce the incidence of cerebral palsy in preterm infants.
What are the main contributors to preterm labor due to infection?
Bacterial vaginosis, chorioamnionitis, ascending infections from the vagina and cervix.
What is the significance of Braxton Hicks contractions?
These are irregular, non-rhythmic contractions that can be mistaken for false labor.
What are common medications used as tocolytics?
Magnesium sulfate, beta-adrenergic receptor drugs, prostaglandin inhibitors, calcium channel blockers.
What lifestyle factors increase the risk of preterm birth?
Smoking, drug use, poor nutrition, low maternal weight gain, and physical activity extremes.
What is the recommended management for preterm premature rupture of membranes (PPROM) at 34 weeks?
Delivery is recommended, along with group B streptococcal prophylaxis and corticosteroids.
What genetic factors are linked to preterm birth?
Genetic mutations affecting collagen, elastic fibers, and immunoregulatory genes are implicated.
What is a rescue cerclage?
A rescue cerclage is placed when cervical incompetence is identified in women with threatened preterm labor.
What role do antimicrobials play in preterm labor?
Antimicrobials can prolong pregnancy by reducing infection-related preterm labor but should not be used routinely in women without infection.
Oxytocin receptor antagonist in myometrium and decidua
Atosiban
Prostaglandin inhibitor
Indomethacin
50-100 mg LD, 25-50 mg PO q8 for 1-2days
Low birthweight refers to neonates weighing
1500 to 2500 g
extremely low birthweight refers to
<1000 g
lower limit o etal maturation compatible with extrauterine survival
threshold o viabil- ity
