Preterm labor: clinical

management

Jana Skrzypczak

Jakub Kornacki

Division of Reproduction , University of Medical

Sciences, Poznań

Criteria for diagnosis of

preterm labor

1. Gestational age of 22-37 weeks

2. Documented uterine contractions ( at least 5-8

min apart and lasting 30 sec.)
3. Ruptured membranes

If membranes are intact at least one of the

following is needed:

• documented cervical changes
• cervical effacement of greater than 75%
• cervical dilatation of greater than 2 cm

Prediction of preterm

labor

Risk scoring

• previous preterm delivery

• low socioeconomic status
• short stature
• maternal age < 21 or > 36

years old

• multiple pregnancy
• vaginal bleeding

Risk scoring

Women with one previous preterm

delivery have a 15% chance and

those with two previous preterm

births have a 41 % chance of another

preterm delivery

Preterm labor

Maternal risk

The two most common maternal
condition associated with preterm birth
are:

- pregnancy induced

hypertension
- antepartum bleeding

Preterm labor

Maternal risk

• intrauterine infection (47%)
• placental abruption or placenta previa

(40%)

• uteroplacental insufficiency (

e.g.

hypertension , insulin dependent diabetes,
drug abuse, smoking, alcohol consumption)

• uterine factors (20%, e.g. fibroid uterus

)

Preterm labor

Maternal risk

• cervical incompetence (17%)
• immunological factors (33%)
• trauma ( surgical , others , 3%))
• idiopathic (1%)

Preterm labor

Fetal/ neonatal risk

• intrauterine fetal death
• intrauterine growth restriction
• major congenital anomalies
• repetitive variable decelerations
• absent or reversed diastolic flow in

Doppler examination of umbilical artery

• unrecognized intauterine infection
• complicated multiple pregnancy

Indications for delivery of a

preterm baby

• infection
• antepartum haemorrhage
• cardiotocographic fetal distress
• prolapsed cord
• failure of the fetus growth
• maternal consideration

Prediction of preterm
labor/delivery

• an increased frequency of baseline uterine

contractions

• cervix changes - shortening , softening and

progressive dilatation

• cytokines -increased concentration of IL-6 in

cervical and vaginal secretion

• fetal fibronectin increased concentration in

cervical and vaginal secretion

 corticotropin releasing hormone - promotes

uterine

•

contractions

Diagnosis

• preterm onset of uterine contractions
• cervical changes

assesed by:

- transvaginal ultrasound

- visual inspection
- digital palpation

Differential diagnosis

• urinary tract infections
• small placental abruption or infarction
• degenerating fibromyomata
• appendicitis
• gastroenteritis
• hydramnios
• systemic febrile illneses ( malaria or

pneumonia)

Management

• hospital rest and sedation

The purposes of arresting the preterm

uterine contractions are:

-

to permit the administration of a course of

corticosteroids (48 hours)

- to prolong the pregnancy and gain fetal

maturity

Management

• monitoring uterine activity
• regular cervical assesments (clinical and

ultrasound)

• bacterial vaginal screening

All patients with preterm labor need

documentation of the presence or
absence of lower genital tract infection

In a population at risk for preterm

delivery

22% of preterm birth and

44% of cases with premature rupture

of membranes

were attributed to abnormal bacterial

colonization of the genital tract

Management

Tocolytic therapy

1. Magnesium sulfate
2. Indomethacin
3. Beta -sympathomimetics ( most

widely used)

4. Oxytocin inhibitor (Atosiban)

Management

Beta -sympathomimetics

Side effects

- cardiovascular ( increase in heart rate , a rise in

systolic pressure , a decrease in diastolic

pressure)

- elevation of plasma glucose

- decrease of plasma potasium level

A rare but more serious side effect is the

development of pulmonary edema ( 3 per 1000)

Management

•

Beta-sympathomimetics

•

Contraindications

• cardiac arythmia
• valvular disease
• ischemic heart disease
• heart malformation
• hyperthyreosis

Management

Indomethacin

is

reserved for cases of

preterm labor:

• before 32 weeks
• not responded to beta-sympathomemimetics
• with no clear evidence of intrauterine

infection

Loading dose of 50 mg orally or 100 mg rectally

followed by 25 mg orally every 4-6 hours for 24
-36 hours

Management

Indomethacin

Side effects

in the mother:

- gastrointestinal irritation and

bleeding

- trombocytopenia
- allergic reactions

Management

Indomethacin

Side effects

in the newborn :

- preterm closure of ductus arteriosus

- oligohydramnios

- periventricular leukomalacia ?
- necrotizing eneterocolitis (NEC) ?

Management

•

Indomethacin

•

Contraindications

•

peptic ulcer disease

• haemathological disorders
• oligohydramnios
• IUGR

Management

• Magnesium sulfate

the drug of

choice for patients with

diabetes

mellitus

and

heart disease

• Initial dose: 6 g ( 12 ml of 50% MgSO

4

in

100 ml 5% dextrose ) over 15-20 min

• Maintenance dose:1 g/h for 24-72 hours

• appropriate therapeutical level 5,5 -7 mg/dl

Management

• Magnesium sulfate

Complications  respiratory depression

( at magnesium levels of 12 to 15

mg/dl)

• The antidote - calcium gluconate 1 g iv.

In 10% solution

• Contraindications: heart block, advanced

renal failure, myasthenia

Management

Calcium channel blockers

•Nifedypine

Cardiovascular side effects:

severe tachycardia and

hypotension ( in both the

mother and the neonate)

Assess for medical contraindications

to tocolysis

Use tocolysis with considerable caution

in patients with cardiac disease who

require medication or have a history of

congestive heart failure , cardiac

surgery , significant pulmonary disease ,

renal failure , or maternal infection (e.g.

pneumonia , appendicitis ,

pyelonephritis).In these cases , consult

with a maternal -fetal medicine

specialist prior to the initiation of

tocolysis

Management

Neonatal morbidity and mortality by
gestational age

Gestational

Age , wk

Survival Respiratory

Distress

Syndrome

Intraventricular

hemorrhage

Sepsis

Necrotizing

enterocolitis

Intact

24 40% 70% 25%

25% 8% 5%

25 70% 90% 30%

29% 17% 50%

26 75% 93% 30%

30% 11% 60%

27 80% 84% 16%

36% 10% 70%

28 90% 65% 4%

25% 25% 80%

Management

Neonatal morbidity and mortality by
gestational age

Gestational
Age , wk

Survival Respiratory

Distress

Syndrome

Intraventricular
hemorrhage

Sepsis

Necrotizing
enterocolitis

Intact

29 92% 53% 3%

25% 14% 85%

30 93% 55% 2%

11% 15% 90%

31 94% 37% 2%

14% 8% 93%

32 95% 28% 1%

3% 6% 95%

33 96% 34% 0%

5% 2% 96%

34 97% 14% 0%

4% 3% 97%

Management - fetal
therapy

Corticosteroids and other agents to

promote pulmonary maturation in
premature newborn

24-34 weeks gestation

• glucocorticoids

• thyroid releasing hormone (TRH)

• 50% decrease in the incidence of RDS

Fetal therapy

Betamethasone (Celestone)
at 12,5 mg every 24 hours
for 2 doses

Present recommendation

-single dose

Management

Glucocorticoids

• Theoretical risk

for the fetus:

- lower birth mass

- infections
- adrenal suppression

for the mother:

- infections

- pulmonary edema

( in combination

with

betasympathomimetics)

Mode of delivery

before 26 weeks

• careful discussion with

parents

• aim for vaginal delivery ;

experienced

pediatrician in attendance

Mode of delivery

after 26 weeks

• if cephalic presentation , aim for

vaginal

delivery with cesarean for normal
obsteric indications

• if breech presentation , aim for

cesarean

section