Preterm Labor & Preterm Birth

Family Medicine Specialist CME

Vientiane, Lao PDR

December 10 – 12, 2008

Objectives

• Define preterm labor and recognize significance to infant mortality & morbidity

• Describe common causes of preterm labor

• Describe how to diagnose preterm labor

• Explain the management of preterm labor & preterm birth

Preterm Labor

• Regular uterine contractions

• Progressive cervical dilatation

• +/- effacement

• Less than 37 weeks gestation

• Usually results in preterm birth

Preterm Birth

• Birth occurring before 37 completed weeks of gestation

• Dated from Last menstrual period (LMP)

Incidence

• Occurs in 7 – 10% of all pregnancies

• Has not changed in 30 years in countries such like Canada

• Approximately 1 – 2% of pregnancies deliver before 34 weeks gestation

Significance

• Babies born >34 weeks gestation in centres with NICU have survival rates equal to babies born at term

• Babies born <34 weeks gestation have long term adverse outcomes– Respiratory complications– Central nervous system complications– Neurodevelopmental delays– Blindness & deafness

• Babies born <30 weeks gestation have high mortality and morbidity

Etiology

• Preterm pre-labor rupture of membranes• Spontaneous preterm labor with intact

membranes• Other causes

– Placental abruption– Chorioamnionitis– Gestational hypertension– Abnormal fetal monitoring findings– Intrauterine growth restriction

Risk Factors

• Prior history of spontaneous preterm birth

• Preterm pre-labor rupture of membranes

• Antepartum hemorrhage

• Uterine distension– Twins (multigestational pregnancy)– Polyhydramnios

• Incompetent uterus/uterine abnormality

• Fetal anomly

Risk Factors

• Infection– Chorioamnionitis– Bacteriuria– STI’s– Peridontal disease– Bacterial vaginosis + prior preterm birth

• Drugs, smoking (>10 cigs/day), lifestyle• Domestic violence• Demographic factors

– Maternal age <18 or >35 years of life– Maternal weight <55 kg - malnourishment

Diagnosis

• Early– Educate patients about early signs &

symptoms of preterm labor• Contractions• Vaginal fluid loss• Vaginal bleeding• Maternal perception of vaginal pressure, low dull

backache, vaginal discharge

Diagnosis

• Establish dates of pregnancy– LMP (Last Menstrual Period)– EDD (Estimated Date of Delivery)– Current gestational age

• Identify risk factors

• Evaluate for uterine contractions

• Assess for cervical changes

Management Objectives

• Early diagnosis of preterm labor

• Identify & treat underlying causes of preterm labor

• Attempt to arrest labor, if appropriate

• Intervene to reduce neonatal morbidity & mortality

Prolongation of Pregnancy

• Use of tocolysis to prolong pregnancy for 48 hours allows:– Betamethasone treatment– Transfer of mother to appropriate neonatal

centre for delivery of baby

Prolongation of Pregnancy

• Contraindications for continuing pregnancy– Gestational hypertension with proteinuria /

adverse events for mother– Chorioamnionitis– Mature fetus– Imminent delivery– Intrauterine death or lethal fetal anomaly

Betamethasone treatment

• Dose: 12 mg IM for 2 doses, 24 hours apart

• Requires 48 hours for maximum benefit

• Gestational age: 24 to 34 weeks

• Crosses placenta and accelerates lung maturity

• Helps prevent intra-ventricular hemorrhage and necrotizing enterocolitis

Antenatal Steroid Cautions

• If immediate delivery indicated, do not delay for steroid effect

• If cardiac disease, active TB, chorioamnionitis, placental abruption

• Transient increase in WBC count

Tocolytics

• Some evidence for:– Nifedipine (Calcium Channel blocker)– Indomethacin (Prostaglandin Synthetase

Inhibitor)• Gestational age <32 weeks

– Risk of fetal premature closure of ductus arteriosis

• 100 mg suppository PR for transport

Maternal Transport

• Mother should be transported to hospital best suited for delivery of neonate

• Requires transportation with skilled birth attendant

• Consider risk of delivery en route• Consider risk of journey to maternal /

neonatal well-being

Maternal Transportation

• Contraindications– Unstable mother– Abnormal fetal monitoring– Imminent delivery– Lack of skilled birth attendant to accompany

mother– Weather or hazardous conditions for travel

Prevention

• Screen & treat for asymptomatic bacteriuria

• Screen & treat for STI’s

• Education of patients for signs & symptoms of Preterm labor

Conclusion

• Diagnosis preterm labor early to provide for appropriate intervention and treatment

• Treat with betamethasone if appropriate to enhance fetal lung maturity

• Use tocolysis to allow for betamethasone to work and allow for maternal transfer to appropriate hospital