Preterm labor

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Preterm labor

• Flint Womens Clinic

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Introduction

• Preterm birth is the leading cause of neonatal
  mortality in the U.S.
• Preterm labor precedes preterm birth in 40-50 of
  cases
• 467,000 preterm births in U.S. yearly
• 11.5 of deliveries are prior to term

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Introduction

• Preterm births are responsible for 75 of
  neonatal mortality
• Preterm birth is responsible for 50 of the long
  term neurologic impairment in children
• The incidence of preterm birth has changed little
  in 40 years

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Introduction

• Preterm labor is defined as defined by regular
  uterine contractions that occur before 37 weeks
  gestation and are associated with cervical
  change, birth prior to 20 weeks is an abortion.

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Perinatal Morbidity

• Pulmonary- RDS bronchopulmonary dysplasia
• Cardiovascular PDA, persistent fetal circulation
• CNS IVH, cerebral palsy, seizures, sensory
  deficits
• GI NEC
• Metabolic hypoglycemia, hypocalcemia, jaundice

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Perinatal morbidity

• Infections GBS, E. Coli
• SIDS
• Psychosocialgt prevalence of child abuse

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Symptoms of preterm labor

• None
• Pelvic pressure
• Increasing discharge
• Contractions (painless or painful)
• Back ache
• Menstrual cramps

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Traditional Treatment

• Bed rest
• Abstention from intercourse and orgasm
• Hydration

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Risk factors for preterm delivery

• Prior preterm delivery(15-30)
• Non white race
• Age over 35 or under 17
• Low socioeconomic status
• Low pre-pregnant weight(lt50kgs)
• Vaginal bleeding in more than one trimester
• Smoking

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Risk factors for preterm delivery

• Physically stressful jobs may increase risk
  (greater than 40 hour per week of standing)
• Uterine anomolies
• Second trimester abortion
• Preterm rupture of membranes

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Risk factors for preterm delivery

• Multiple first trimester abortions
• Cervical conization
• Fibroids
• Polyhydramnios
• DES exposure
• Anemia
• Narcotic and cocaine use
• Periodontal disease

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Causes of preterm delivery

• Placental abruption
• Uterine over distension
• Cervical incompetence
• Infections (chorioamnionitis), associated
  infections BV, ureaplasma, mycoplasma,
  peptostreptococcus, and bacteroides

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Causes of preterm delivery

• Ruptured membranes
• Placenta previa
• Placental abruptions
• Diabetes
• HTN
• Connective tissue disorders
• Pyelonephritis

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Assessment of patients in preterm labor

• History (Prior PTL, membrane status, discharge,
  fevers, number or size of fetus, associated
  medical problems)
• Tocodynamometer and FHR monitoring
• Physical exam- fundal height and tenderness,

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Assessment of patients in preterm labor

• Labs-CBC, UA /- culture, electrolytes
• Sterile speculum exam obtaining cultures for
  group B strep, BV, GC, Chlamydia, obtain fetal
  fibronectin
• Cervical length measurement
• The last thing is the cervical digital exam

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Biologic markers for predicting preterm birth

• Home uterine monitoring- no evidence that it is
  of any benefit ACOG does not recommend it
• Salivary estriol- still considered
  investigational by ACOG
• BV-the most recent evidence does not support
  screening women for BV as treatment has not
  affected outcomes (treat symptomatic pts)

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Biologic markers for predicting preterm birth

• Cervical length measurement- many studies have
  confirmed an association with cervical shortening
  and preterm delivery. When combined with
  positive fetal fibronectin and length less than
  2.5 cm, this is a strong predictor of preterm
  delivery

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Biologic markers for predicting preterm birth

• Fetal fibronectin- need intact membranes, less
  than 3 cm dilated, not useful before 24 weeks or
  after 34 weeks 6 days
• Negative fetal fibronectin gives about a 95
  chance of the pregnancy continuing 14 days or
  more. A positive test is not as predictive.

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Predicting preterm birth

• Use history, cervical length less than 2.5 cm
  (some authors 3.0 cm), fetal fibronectin
  positive, cervix 80 effaced, and or dilation
  above 2cm (some authors 3 cm), or a 1 cm change
  in cervical dilation.

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Treatment of preterm labor

• IV hydration
• Treat any infections (usually start IV
  antibiotics empirically)
• Terbutaline 0.25 mg sub Q, can be given q 20 min,
  keep pulse under 120
• MGSO4 4-6 gram bolus then run at 2-3 grams per
  hour

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Treatment of preterm labor

• Calcium channel blockers 30 mg loading dose then
  10-20 mg every 4-6 hours (nifedipine) avoid using
  MGSO4 at the same time
• Indomethacin 50 mg rectally or 50-100 mg orally
  then 25-50mg every 6 hours only for a 48 hour
  period also use only less than 32 week

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Treatment of preterm labor

• Betamethasone 12mg IM 2 doses 24 hours apart or
• Dexamethasone 6mg IM q 12 for 4 doses
• Do not use prior to 24 weeks and after 34 weeks

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Why use steroids

• Decreased risk of RDS
• Decreased risk of Necrotizing enterocolitis
• Decreased risk of intra ventricular hemorrhages

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Down side of steroids

• Decreased ability to fight infection
• Occasionally increases contractions
• Increased risk of pulmonary edema

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Management

• First determine if it is truly labor
• Monitor contraction and assess cervical change
• If fetal fibronectin is negative no treatment
  needed, unless the cervix is less than 2.5cm
• Once a patient contracts regularly consider bed
  rest

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Management

• Treat infections
• Treat asymptomatic bacturia
• Decrease activity
• Decrease or eliminate smoking or drugs
• Because of unknown group B strep status give
  penicillin until cultures are back

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Management

• No method of treatment has proven to work
• Increased maternal surveillance does make a
  difference

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Contraindications of tocolysis

• Severe PIH
• Abruption
• Chorioamnionitis
• Fetal death
• Severe IUGR
• Severe bleeding
• Fetal compomise
• 5cm dilated or more

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Outcomes

• 23 weeks
• 24
• 25
• 26
• 27
• 28

• 0-7
• 0-50
• 0-29
• 56-67
• 56-100
• 88-91

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Outcomes

• Most NICUs report near 100 survival in the
  absence of major anomolies
• Malformations are the number one cause of
  neonatal death, 2 is prematurity (in blacks
  prematurity is 1)

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Review

• There are risk factors for preterm delivery but
  the associations are weak. Assess each patient
  individually
• Act quickly- collect information and labs and
  check the cervix for dilation and length
• Start tocolytics and antibiotics

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Review

• If gestation is prior to 34 weeks transfer to
  tertiary care center is indicated if time permits
• No therapy is proven superior or to work at all
• The combination of fetal fibronectin and cervical
  length are very good negative predictors

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Review

• Many patients will have contractions but if no
  cervical change it is not preterm labor

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Introduction

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Topic Three

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Real Life

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What This Means

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Next Steps

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