Preterm Labour

Dana Romalis, PGY-3

March 12, 2004

Preterm Labour

Definition Why we should be concerned? Causes Prevention Management Future directions

Case#1: Patient “A”

Ana is a 23yo G2P1001 who comes to you to establish prenatal care at 8 wks. Her first child was born at 33 wks.

What do you need to know? How will her care be different?

Case#2: Patient “B”

Barbara is a 23yo G2P1001 prenatal patient who calls your beeper at 8am. She has been having regular contractions since 6am, and she thinks they’re getting stronger. You calculate that she is 26 weeks.

What do you need to know from her? What do you tell her will happen next?

Case#2: Patient “C”

Charlene is a 23yo G2P1001 prenatal patient who calls your beeper at 4am. She’s concerned because she was feeling funny all day, and she just woke up in a wet pool. You calculate that she is 32 weeks.

What do you need to know from her? What do you tell her will happen next?

Definitions: Labour

Regular contractions of sufficient frequency, intensity, and duration to result in cervical dilatation and effacement

Preterm labour (ACOG / AAP) Labour from 20-37 wks with documented uterine

contractions( ≥4 in 20 min, or ≥ 6 in 60 min) with• Cervical dilatation greater than 2 cm or• Cervical effacement of ≥ 80% or• ROM or• Documented cervical change

MORE definitions! Low birthweight (<2500 g) Very low birthweight (< 1500 g) Extremely low birthweight (<1000 g) PROM (premature rupture of membranes)

ROM before the onset of labour PPROM (preterm premature ROM)

ROM at <37 wks, before the onset of labour

Why do we care? Preterm birth carries an increased risk of low

birthweight, which is a risk factor for infant mortality and long term morbidity

Why do we care?• Major causes of morbidity:

• Respiratory Distress Syndrome • Hypoxia, sepsis

• Chronic lung disease• Intraventricular hemorrhages --> CP/ Mental Retardation• Retinopathy of prematurity --> blindness• NEC

• Survival rates: • 23 wks = 20%• 29 wks/1000 g = 90%• 32+wks/1500g = 99% survival

Why do we care? In the USA:

The rate of premature birth increased from 1981 to 2000 (9.4 -11.9 %) March of Dimes.

Huge caregiver burden/family strain. Extremely high financial costs of NICU care.

In some cases, this may have been prevented.

Risk factors

Idiopathic (most common) Fetal

Multiple gestation Congenital abnormalities

Maternal-Fetal PPROM polyhydramnios

Risk Factors cont… Maternal

-PMHx: prior preterm birth, abortion, stillbirths-Placenta: previa, abruption, abdomnal trauma-Medical: Preeclampsia/HTN, Uncontrolled diabetes, heart dz,

renal dz, vascular dz, coagulopathies, thromboembolic dz-Infection: bacteruria, pyelo, STI, BV, chorio-Uterus: fibroids, myomectomy, abnl anatomy,-Cervix: hx of incompetence, cone bx, or LEEP.-Social: low SES, lack of prenatal care, poor nutrition, low

BMI, domestic violence, low preconception BMI, drugs (cocaine), alcohol, smoking, unmarried, family stress, non-white, maternal age <18 or >35.

Prevention

“Good” prenatal care (>8 visits). Identify at-risk pregnancies, and intervene

to reduce/treat modifiable risk factors. Treat silent urinary tract infections. Treat BV@ GA<16-20wks, with 7 days of

metronidazole.Am J Ob Gyn,189(1), 7/1/03

Educate pts on signs/symptoms of PTL.

Prevention: Current studies- Cervical length: Women with a shorter

cervix (20.6 mm vs. 31.3 mm) and those with progressive cervical shortening (0.5-0.8 cm/wk vs. 0.03 cm/wk) are at increased risk of premature delivery.

- potential for screening for early steroid administration?

Prevention: current studies- Fetal fibronectin: A biological glue that helps

attach the fetal sac to the uterine lining.  Normally seen in vaginal secretions up to 22 weeks of pregnancy, then not until one to three weeks before delivery. If FFN is seen on a vaginal swab between 24 - 34 weeks of pregnancy, a woman appears to be at increased risk of premature labor.

- If negative, this test is useful in determining who will NOT deliver within the next 7-14 days.

- You can imagine this would be a lot of vaginal swabbing…

Prevention: out the window- Salivary estriol.  Because estrogen levels in

the saliva appear to increase just before labor, attempts have been made to measure it.  This test is not accurate.

- Home uterine monitoring.  High-risk women have been monitored for painless contractions in an attempt to diagnose premature labor early, when it was most treatable.  Several studies have shown that HUM is not effective in preventing premature delivery.

Assessment If bleeding: bedside ultrasound first (placental

location) If not bleeding:

Sterile speculum (nitrazine, pooling, ferning) Digital cervical exam Contraction pattern Non-Stress Test or Biophysical Profile Tests: UA/cx, +/-GBS/drug screen/wet prep/GC/CT

as indicated.

Management

Delay delivery Hydrate Bedrest/pelvic rest for 48 hours Fetal monitoring Tocolysis (more later) Transfer to center with a NICU if possible

Management: part 2

• Prepare fetus for the outside world:- Enhance pulmonary maturity w/steroids if

23-34 wks. Confirm with L:S ratio.

• Treat presumptively for GBS with broad-spectrum abx.

(IV ampi or clinda are Weiler standards).

Tocolysis & Steroids

- Tocolytics before 34 wks have been shown to delay delivery for 48 hrs, allowing time to treat with corticosteroids, which enhance maturation of fetal lungs / organs.- Resulting in a reduction in:

- infant mortality by 30% - RDS by 50%, - IVH by 70%.

ICSI guidelines

Acceptable Regimens Tocolysis

Magnesium sulfate (4 g IV bolus, then 2 g/hr infusion, forgoal serum level of 5-8 mEq/L)

Terbutaline Indomethacin Niedipine Ritodrine

Future…?atosiban (oxytocin antagonist)

Steroids (48 hrs) Betmethasone 12 mg

IM q24h x2 doses Dexamethasone 6 mg

IM Q12h x 4 doses.

Patient “A” Ana is a 23yo G2P1001 who comes to you to

establish prenatal care at 8 wks. Her first child was born at 33 wks.

What do you need to know? Risk factors that are modifiable BV status

How will her care be different? BV screen at <16-20 wks Risk specific interventions

Patient “B” Barbara is a 23yo G2P1001 prenatal patient who

calls your beeper at 8am. She has been having regular contractions since 6am, and she thinks they’re getting stronger. You calculate that she is 26 weeks.

What do you need to know from her? ?ROM, contraction pattern, vag discharge?

What do you tell her will happen next? Weiler: ua/tox, FHR tracing, digital exam, cervical cx,

GBS cx, +/- cervical U/S/BPP. If in PTL, will get admitted for tocolysis, steroids, and abx.

Patient C Charlene is a 23yo G2P1001 prenatal patient

who calls your beeper at 4am. She’s concerned because she was feeling funny all day, and she just woke up in a wet pool. She is 32 wks.

What do you need to know from her? Contractions, vag discharge

What do you tell her will happen next Weiler: sterile spec - if pPROM, will get steroids,

abx, tocolysis.

References Williams Obstetrics, 21 ed, 2001. Oski’s Pediatrics, 3rd 3d, 1991. March of Dimes website. UpToDate. ICSI guidelines. “Tocolytic treatment for the management of PTL: a review of

the evidence,” AJOG 188(6), 6/03. “Antibiotic therapy for the treatment of preterm labor: A

review of the evidence,” AJOG 186(3), 3/02. “Antibiotic treatment of BV in pregnancy: a meta-analysis,”

AJOG, 188(3), 3/03.