Preterm Labor & Birth

Preterm labor (PTL)

Regular uterine contractions that result in changes in the cervix BEFORE 37 completed weeks of gestation

Preterm birth (PTB)

Birth between 20 0/7 and 36 weeks 6/7 gestation.

• Very preterm

• Moderately preterm

• Late preterm (less complications when bigger)

Very preterm

Infant born before 32 completed weeks of gestation

Moderately preterm

Infant born between 32-34 weeks of gestation

Late preterm

Infant born between 34-36 weeks of gestation

What are the risk factors for Spontaneous Preterm Birth?

• H/O previous spontaneous PTB (btwn 16-36wks of gestation)

• Nonwhite race (black)

• Genital tract infections

• Multifetal gestation

• Bleeding of uncertain origin in pregnancy

• Uterine anomaly

• Use of assisted reproductive technology

• Cigarette smoking, substance use, or misue

• Prepregnancy underweight and prepregnancy obesity

• Periodontal disease

• Limited education and low socioeconomic status

• Late entry into prenatal care

• High levels of personal stress in one or more domains of life

What are the causes of indicated preterm birth?

• Chronic conditions (DM, CHTN)

• OB disorders, infections

  • Previous cesarean birth

  • Cholestasis

  • Placental disorders (abruption or previa)

• Fetal disorders

• Obesity, AMA (advanced maternal age)

• Preeclampsia

• Medical disorders

  • Seizures, thromboembolism, connective tissue disorders, asthma and chronic bronchitis, maternal HIV or active herpes infxn, obesity, smoking

What are other causes of spontaneous pre-term labor and pre-term birth?

• Social determinants: poverty, socioeconomic background, lack of access to PNC

• Genetics: patient w/ h/o PTL or sibling w/ history

• Cervical length: cervical shortening w/out being in labor (<2cm long)

• Fetal Fibronectin test: glycoprotein found in the plasma and is produced during fetal life

  • It’s presence/absence in vaginal secretions during late 2nd or early 3rd trimester is used as a diagnostic test for PTL.

  • A positive test may be r/t placental inflammation leading to spontaneous PTL

How to identify and prevent pre-term labor?

• Assessment: identify the risk factors during pregnancy

• Prevention:

• Presentation

• Management

How to prevent pre-term labor?

• Preconception counseling esp. those w/ h/o of PTL

• Promote good health activities; d/c smoking, alcohol, drug use

• Administration of supplemental progesterone between 16-36 weeks of gestation (maintains endometrium and keeps it relaxed so that it doesnt contract prematurely)

What is the presentation of pre-term labor?

• Uterine activity: painful uterine contractions

• Discomfort:

  • Lower ABD or back pain

  • Pelvic pressure, urinary frequency, increased vaginal discharge, spontaneous rupture of membranes

What is the management of pre-tern labor?

• Physical & sexual activity restriction

• Home care

What are the drugs to suppress uterine activity?

• Tocolytics

  • Magnesium sulfate: CNS depressant, relaxes smooth muscles (uterus)

  • Given to delay birth; reduces neonatal morbidity & mortality

• Beta-adrenergic Agonist

  • Terbutaline (Brethine): relaxes smooth muscles inhibiting uterine activity, causing bronchodilation

    • Contraindications: h/o cardiac disease, HTN disorders, DM

What is the cervical dilation confirmation of pre-term labor?

At least 4cm

What is the management of inevitable pre-term birth/fetal & early neonatal loss?

• Staff prepares for preterm delivery and resuscitation if needed

• Prepares for transfer for advanced neonatal care (based on age)

• In the event fetal or neonatal death is suspected, discuss situation with parents prior to delivery

• Unit of choice discussed with mother– maternity or general med/surg