Medical Archive

Introduction

Definition of preterm birth

??: 20+0~36+6
34~36?: late preterm, ??? 70%

Preterm birth rate trends

Preterm newborn morbidity

Threshold of Viability

24? and 750g ??? ?? viability? ?? C-sec ??

Good Px
Female
Singleton
Steroid
Gestational age?
Weight?

Late-preterm birth

Causes of preterm birth

Spontaneous preterm labor

• Uterine distension
  • ???, ????
• Maternal-Fetal stress
  • Stress ? HPA axis ? maternal E3 ? ? ?? ??
• Cervical dysfunction
  • Risk factors
    • Collagen defects
    • Uterine abnormalities
    • Cervical conization (m/i)
    • Obstetric injury
  • Diagnosis criteria (any 1 of the following)
    • Painless cervical dilation in the current pregnancy
    • A second-trimester cervical length of <2.5cm + a prior preterm delivery
    • ?2 prior consecutive, painless, second-trimester losses, which typically present with mild symptoms (eg, vaginal discharge, light spotting) followed by precipitous delivery.
• Infection
  • Cytokine ? ??? PG ? ??? HPA axis ??

PPROM

Multifetal pregnancy

1/6

Contributing factors

• Threatened abortion – bleeding
• Lifestyle Fators
• ?? / ?? / ?? stress
• Black / ? ???? / Periodontal dx / Prior preterm (10% ??)
• <18? or 59?< (??? risk? ?)
• ??? ??? 2? ??? ??
• Infection (25-40%)

?? ?? screening

Home uterine-activity monitoring
Bacterial vaginosis screening
Screening for risk of preterm

Diagnosis

Symptoms

??: 4?/20? or 8?/60? + ??? ??

• Regular contractions with cervical change
  • Fetal fibronectin (FFN) not indicated.
• Regular contractions w/o cervical change
  • 34-37 weeks gestation -> FFN not indicated
  • <34 weeks gestation -> FFN test

Cervical change

Dilation >1cm
Effacement >80%

Ambulatory uterine monitoring

Fetal fibronectin

• Secreted whenever the interface is disrupted (ie, labor)
• High until 20 weeks gestation, are low during the mid-second and third trimesters, and increase again at term, when contractions disrupt the decidual-chorionic interface.
• 22~35?, ?50ng/mL ?? (+)
• ~22???? ???? ??? ???? ??.
• Negative (<50ng/mL)
  • Low likelihood of delivery within the next 2 weeks
  • Can resume routine prenatal care and expectant management

Cervical length measurements

• TVUS > TAUS
• 24? ?? 35mm.
• Funneling: 25% of cervix.
• If +preterm Hx ? predictive

Preterm birth prevention

Cervical cerclage

• Indication
  • Cervical insufficiency
    • Hx / IIOC / short cervix / rescue (emergency)
• Procedure
  • Performed in the first trimester (ie, 12-14 weeks gestation)
  • A suture is placed to reinforce and add tensile strength to the cervix
  • Removed at term to allow vaginal delivery
• Cf) pessaries are no longer used for management of cervical insufficiency.

Prophylaxis with Progestogen Compounds

• IM 17-OHPC (hydroxyprogesterone)
  • Maintains uterine quiescence
  • Short cervix identified on ultrasound between 16 and 24 weeks gestation.

Prior Preterm Birth and Progestogen Compounds

Progesterone Use without Prior Preterm Birth

Geographic-Based Public Health-Care Programs

??? ????

Sono? Cervical length
fetal fibronectin level

Management of preterm premature rupture of membranes (PPROM)

Natural history

Hospitalization

???. ???? ?? ??!

1. ??: ??? ?? ??
2. Nitrazine test: pH >6.5, (???. ??, ?? ?? ??? ?? ?+)
3. ???? ????: Arborization or ferning
4. ??? Indigo carmine ??? vagina? ?
5. Septic abortion: S.aureus > GNB(eg, E.coli), GBS

Intentional delivery

???? ??? ??? ??

• Labor (+)
• Fetal distress (+)
• Chorioamnionitis (+): ROM+38? ??
• Subclinical amnionitis: ???? gram (+)
• ?? ??? ?? ??: DM, ?????
• ?? ??? ?? ??
• ?? ??

• C-sec
  • 24? ?? or 750g ?? ?????…
  • Fetal distress? ??? ??+Breech presentation
• Vaginal delivery
  • Chorioamnionitis, other infection
  • 34? ?? or ? ??? ??
  • ??? ??? ???? ?

Considerations with Expectant Management

GA	34~36	32~33	24~31
Betamethasone	±	+	+
Tocolytics	–	+ (CCB)	+ (Indomethacin)
GBS prophylaxis	If +/unknown	If +/unknown	If +/unknown
MgSO4	–	–	+

~23?: ?? ??, only observe

MgSO4 provide fetal neuroprotection (eg, cerebral palsy)

Clinical Chorioamnionitis

Risk factors

• Prolonged rupture of membranes (>18 hours)
• Preterm prelabor rupture of membrane (PPROM)
• Prolonged labor
• Internal fetal/uterine monitoring devices
• Repetitive vagnial examinations
• Presence of genital tract pathogens

Diagnosis

• Maternal fever PLUS ?1 of the following:
  • Fetal tachycardia (>160/min)
  • Maternal leukocytosis
  • Purulent amniotic fluid

Fever, fetal tachycardia
+/- maternal tachycardia, uterine tenderness, and malodorous or purulent amniotic fluid.

Management

• Require therapeutic antibiotics and immediate delivery (eg, induction of labor), regardless of gestational age.

Complications

Maternal: postpartum hemorrhage, endometritis
Neonatal: preterm birth, pneumonia, encephalopathy

Antimicrobial Therapy

Corticosteroids to Accelerate Fetal Lung Maturity

• Patients ate <37 weeks gestation who are at imminent risk
• Contraindication
  • Previable fetuses (eg, <23-24 weeks gestation)
  • No signs of labor (regular contractions with cervical dilation)

Membrane Repair

• Non-cephalilc presentation: umbilical cord prolapse?
• Vaginal delivery ?? ? ???? cerclage ??? ??
• ??? ??? breech?? ??? ? ??. ????.

• ????: steroid, antibiotics, tocolytics? ??? ???
• ???!! But amoxicilliln-clavulanate? ??
  (due to necrotizing enterocolitis), 35-37? ? screening.
  Infection ?? ?? amniocentesis???.
  Routine?? X. ??? ???? CP ?
• Steroid? 24-32?, single dose. 33~34?? controversial
  ?? 24h ? ~ 7?????. DEX > Betamethasone

Management of preterm labor with intact membranes

34? ??: ???? + steroid + tocolytics ± MgSO4 (32? ????)
34? ??: Labor monitoring, active labor ???? GBS?? ???.

Fetal fibronectin: used to identify patients with preterm contractions who are at high risk for preterm delivery.
Fetal lung maturity testing: with uncertain gestational dating to determine timing of delivery

Amniocentesis to Detect Infection

Corticosteroids for Fetal Lung Maturation

Magnesium Sulfate for Neuroprotection

Antimicrobials

Bed rest

Cervical Pessaries

Emergency or Rescue Cerclage

• Contraindication
  • In patients who have bulging or prolapsing amniotic membranes – d/t the high risk of membrane rupture, complications
  • Likely imminent delivery

Tocolysis to Treat Preterm Labor

48?? ?? ??? ??, Hydration/sedation? ?? ????.
34? ???? ?? ???? ??.

• ?-adrenergic agonists
  • Short-term tocolytic: inpatient use
  • ???, ???, ???, ??, myocardial ischemia, pulmonary edema
  • Ritodrine, Terbutaline, Fenoterol
• MgSO₄
• CCB
  • First-line tocolytic: 32-34 weeks
  • Maternal tachycardia/palpitations, nausea, flushing, headache
  • Nifedipine? Mg? ???? ??
• Indomethacin
  • First-line tocolytic: <32 weeks
  • ?PG production
  • Maternal gastritis, platelet dysfunction
  • Fetal vasoconstriction
    • Premature closure of the ductus arteriosus
    • ?Renal perfusion & fetal oliguria ? oligohydramnios – transient and resolves without intervention once the medication is discontinued.
• Atosiban – oxytocin antagonist

Prevention of Intracranial Hemorrhage