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Pre-Term Labor (PTL)
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Pre-Term Labour (PTL
o Labor which begins between 20 and 36.9 weeks resulting in cervical change
o PTL is a description of fetal age – not maturity or size.
Physiology of labor
o Progesterone- from placenta,
 relaxes smooth muscles (uterus),
 tightens the cervix with ropes of collagen
 Production ↓s as body prepares for labor
o Estrogen excites the uterine muscle
 Production ↑ @ end of pregnancy labour
 prompts the production of fatty acid hormones: prostaglandins
o Prostaglandins –
 soften the cervix by digesting the collagen fibers
 A soft cervix will dilate faster
Tocolytics
o Rx’s that relax muscles & prevent softening of the cervix
Assessment: PTL Risk Factors Physiologic
o Infection
o PPROM/PROM
o Incompetent cervix
o STI’s
o Smoking
o Substance abuse
o cocaine
o Domestic violence/trauma
o Multiple gestation
o polyhydramnios
o Maternal Dehydration
o Late, no prenatal care
o Cervical problems
o Placental problems
o Stress
o Maternal illness
o Maternal Age
o Previous PTL or PTB
o Fetal Abnormalities
o Race
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Incompetent Cervix
o Painless dilatation of cervix s contractions, during 2nd trimester
o Presents with bulging or ruptured membranes & inevitable abortion of an immature
fetus
o Repeat in subsequent pregnancies if tx not initiatedHx of losses
o Weekly Transvaginal Ultrasound to monitor cervical length.
o Seen on ultrasound as funneling.
Acquired
o Inflammation
o Infection
o Cervical trauma
o ↑ uterine volume
o Hormonal-Relaxin
Congenital
o Short cervix
o DES exposure
o (Diethylstilbestrol)
o Bicornuate uterus (a uterus that is shaped irregularly. Heart shaped, appearing to have 2
sides instead of being one hollow cavity)
TX: Cerclage (procedure in which cervical opening is closed w stitches to prevent/delay
preterm birth)
o 14-16wks
o Purse-string suture
o cervix is sewn closed during pregnancy, removed at 36-37 wks or
o left in for future pregnancies and a C/S is performed
o TEACH S&S OF LABOUR
Cerclage
o McDonald’s suture (FYI)
o Shirodkar procedure (FYI)
o The risks for both include:
 Infection (if rescue cerclage)
 Damage to cervix during sx.
 Excessive blood loss
 PPROM
 PTL
 Permanent narrowing and stiffening of cervix.
 Tearing of cervix – “chopped meat” effect.
o Teach to monitor for contractions and report immediately to HCP to prevent tearing of
the cervix during labor.
o The cerclage must be removed if labor occurs prematurely.
Elective cerclage
o Outpatient  can go home same day.
o Teach:
 to refrain from Coitus
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to report any contractions to HCP.
Rescue cerclage
o Hospitalized
o Placed when dilation and effacement have already occurred
o 1/3 PPROM (↑↑↑ infection rate)
Fetal Heart Rate in a Premie
o a preterm fetus may have a higher baseline fetal heart rate with apparent reduction of
baseline variability
o fetal baseline heart rate is higher, averaging at 155 between 20–24 weeks (compared to
a term fetus where average baseline fetal heart rate is 140). A premie will have a higher
baseline fetal heart rate
o Before 30 weeks of gestational age, the frequency and amplitude of accelerations are
reduced.
o Pre-term fetus may exhibit accelerations with a peak of only 10 beats per minute lasting
for 10 seconds.
o A premie will have an apparent reduction of baseline variability.
PTL Risk Factors: Microbiological
o UTI
o Cervical infection
o Uterine infection
o How do you get the infection?
o PPROM!!!!!!
PTL: Clinical Manifestations
o Cervical Change- critical criteria
o frequent regular uterine contractions -painful or not painful.
o Change or increase in vaginal discharge (PROM, PPROM)
o Backache, pelvic pressure, thigh pain
o Fetal presenting part engaged
Assessment of PTL Dx Tests
o Monitor uterine contractions: Toco
 6 ctxs. or more per hour Q10min)
o Vaginal exam to determine dilation, effacement
o Dilation greater than 1 cm.
o Effacement greater than 80%
o 4cm or more cant stop labor
o Monitor for ROM
o Fetal fibronectin (fFN) 20-34 weeks
 Fetal Fibronectin (fFN)
 a protein found in fetal membranes that is described as the “glue” that binds
the membranes to the uterus
 it is found in the cervicovaginal fluid before 20th week and rarely after.
 If present between 20 & 34 6/7 weeks (in cervical canal) possible PTD
 Better predictor of who WILL NOT go into labour.
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 Swab test of the vaginal canal
 Expensive ($200)
Planning and Intervention: PTL
o Assess maternal and fetal well being
o Encourage bedrest
o Provide fluids for hydration
o Dehydration stimulates pituitary gland to increase ADH (anti-diuretic hormone) and
oxytocin- this causes contractions which stimulates labor.
o Administer Rx: tocolytics
o Monitor effectiveness of Rx
o Patient teaching RT discharge planning
Tocolytics: Used off label to suppress uterine activity
o Usual criteria used to determine potential use of Tocolytics:
 Cervix less than 4cm. dilated
 Membranes intact
 Less than 37 weeks gestation
o Contraindications to Tocolytic Therapy:
 Severe PIH
 Bleeding
 Chorioamniotis
 Fetal demise
 ROM
o May be used until prenatal steroids become effective (48°)
Beta Adrenergic Agonists
o Ritodrine (Yutopar) – not used anymore
o Terbutaline (Brethine) – used for treatment of Asthma, bronchial dilator, relaxes smooth
muscle tissue of the airways, GI, various blood vessels & uterus –used off label mimics
the action of epinephrine: increases pulse rate & heart muscle contractions
o IV pump (continuous infusion SQ pump)
o PO – 2.5 – 5.0mg. Q2-6 hours
o SQ – 0.25mg. Q 20min. x3 or Q 1-3 hours
o Side effects:
o Main side effects involve cardiopulmonary system
 Maternal and fetal tachycardia
 Palpitations, chest pressure
 Pulmonary edema
 Hypotension
 Hyperglycemia
 Hypokalemia  arrhythmias
 Tremors, jitteriness, apprehension
 Headache
 N/V
 Neonate – may exhibit hypoglycemia & hypocalcemia after delivery
o D/C for:
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 HR >120
 BP < 90/60
 FHR>180
 Maternal
 Pulmonary
 Edema
Calcium Channel Blockers
o Blocks the flow of Ca+ in the myometrium – relaxes smooth muscles, Off label use :
inhibits uterine activity to stop PTL
o Nifedipine (Procardia) Cardiac drug to regulate contractility and lower BP
o Side effects:
 Maternal Hypotension (BP must be assessed prior to administration)
 Maternal Tachycardia
 Palpitations
 H/A
 Dizziness
 Flushing of Skin
 Peripheral Edema
 ↓Uteroplacental blood flow  Fetal Hypoxia & Fetal Bradycardia
NSAIDs Prostaglandin Synthesis Inhibitors
o Indomethacin (Indocin) Indomethacin is a non-steroidal anti-inflammatory drug (NSAID).
It is indicated for the ↓ of inflammation in the tx of rheumatoid arthritis. It also is a
Prostaglandin Synthesis Inhibitors
o Side Effects:
o GI problems (usually given with Maalox)
o Can cause the ductus arteriosus, to close prematurely  NOT to be used after 34 weeks
of pregnancy.
CNS Depressant
o Magnesium Sulfate (MgSO4)
o Primary use as CNS depressant is seizure prophylaxis. It’s main action is to block
neuromuscular transmission
o Used for tx of seizures in eclampsia and preeclampsia.
o Secondary use MgSO4 acts directly as a Ca+ antagonist and is use to regulate cardiac
contractility, relax smooth muscle, vasodilation (↓BP)
o Off label use: relaxes the uterus and ↓ uterine irritability, thus used to delay delivery in
PTL
o Constant infusion of 2gm/hr after bolus of 4gm over 30 min
o Assess blood levels – therapeutic blood level 4-7mg/dL
 Under 4 mag isnt doing anything
o Action: Depresses CNS (respirations, LOC, DTRs)
o Side Effects
 RISK for Pulmonary edema
 Hypotension
 Flush feeling
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 N/V
 H/A
 Lethargy
o Neonatal
 lethargy,
 poor suck reflex,
 delayed motility of GI tract
o CONTRAINDICATED: Myasthenia Gravis or Neuromuscular Disorders exist
o Toxicity:
 Respirations <12
 Hyporeflexia- diminished +1 or absent DTRs 0
 B/P <90/60
 Oliguria urine output <30ml/hr
 Pulmonary Edema (Crackles or Rales)
 Confusion
 Serum MgSO4 >7.0
o Antidote: Calcium Guconate
Evaluation: PTL
o Risk of preterm delivery decreased
o Contractions will be <6/hour with no cervical changes
o Discuss cause, ID & tx of PTL
o ID adaptations of PTL
o Describe appropriate self-care measures
o Pregnancy is maintained
o Birth to healthy infant