Preterm Birth

Present by:Dr.Worapa Asavaritikrai Health Promotion Center Region 4

Objective

• Definition

• Risk factors

• Diagnosis

• Treatment

Definition of Preterm Birth

• 37A birth that occurs before compppppp peepp pp ppppppppp (<259 days)

• Late preterm births, defined as 34-36+6 weeks of gestation (~ 75% of all preterm birth)

36-2

36-3

SURVIVAL RATE OF INFANTS

RAMATHIBODI HOSPITAL (2000-2008)

36-8

Reasons for preterm delivery

• 4 main direct reasons:– Maternal or fetal indications– Spontaneous unexplained preterm labor

with intact membranes– Idiopathic preterm premature rupture of

membranes (PPROM)– Twins

Cunningham et al, 23rd Ed Williams Obstetrics

Definition of PPROM

• Defined as rupture of the membranes before labor and prior to 37 wee ks of gestation

Antecedents & Contributing Factors

• Threatened Abortion• Lifestyle Factors• Racial & Ethnic Disparity• Work During Pregnancy• Genetic Factors• Periodontal Disease

Antecedents & Contributing Factors

• Birth Defects• Interval between Pregnancies & Preterm

Birth• Prior Preterm Birth• Infection• Bacterial Vaginosis

Table 36-6

36-10

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Clinical Practice Guidelinen of Preterm labor

Prevention of preterm birth

• Primary Prevention• Secondary Prevention• Tertiary Prevention

Preventions of Preterm Birth

Primary Prevention

Preconceptional

• Public educational interventions: – Increased awareness– Uterine curettage or endometrial biopsy– Reduce prevalence of smoking– Reduce risk of higher-order multiple

gestation– Socioeconomic approach

During Pregnancy

Smoking cessation in pregnancyPrenatal carePeriodontal care ?? Screening of low-risk women

Smoking cessation

A Cochrane review reported that smoking cessation programmes in pregnancy successfully reduce the incidence of preterm birth (RR 0·84, CI 0·72–0·98)

Lumley J.Cochrane Database Syst Rev 2004

Prenatal Care

High rate of preterm birth in women who receive no prenatal care than from the content of care for those who receive it

Periodontal care

Treatment during pregnency improved periodontal disease and it is safe, but it did not significantly alter rate of preterm birth

Michalowicz BS. N Engl J Med 2006; 355: 1885–94

Screening of low-risk women

-Screening and treatment of asymptomatic bacteriuria prevent pyelonephritis

-Given antibiotic in low-risk does not reduce this risk of preterm birth

Cunningham et al, 23rd Ed Williams Obstetrics

Secondary Prevention

Fetal fibronectin testing

• Glycoprotein • Marker of choriodecidual disruption• Levels > 50 ng/mL ( >22 weeks) associated

with an increased risk of spontaneous preterm birth

The Cochrane Library 2009, Issue 2

Cervical length

• Cervical shortening is a risk factor for preterm delivery

• Especially useful in asymptomatic women : at 24 wks, a cervical length < 25 mm

Table 36-7

Tertiary Prevention

Tertiary Prevention

• Early diagnosis of preterm labour• Treatment of women with acute risk of

preterm birth to arrest preterm labour : tocolysis antenatal corticosteroid use antibiotic for group B streptococcal

prophylaxis

• Regular contractions accompanied by cervical change at less than 37 weeks

• ACOG 1997 criteria preterm labor:– Contractions of four in 20 min. or eight

in 60 min. + progressive change in the cervix

– Cervical dilatation > 1 cm – Effacement > 80%.

Diagnosis of preterm labor

Regular contractions without cervical

change

Threatened preterm labor

Management of Preterm Labor

• PPROM• Preterm labor with intact membranes

Table 36-8

Tocolytic agents

• ACOG 2007 has concluded that tocolytic agents do not markedly prolong gestation, but may delay delivery in some women for at least 48 hours

Tocolytic agents

• Β-Adrenergic receptor agonists– Ritodrine, Terbutaline

• Magnesium sulfate• Prostaglandin inhibitors• Calcium-channel blockers• Atosiban• Nitric oxide donors

Terbutaline

Dose CI Maternal SE Fetal SE

0.25 mg SC every 20 min to 3 h (hold for P>120 bpm)

Cardiac arrhythmia, poorly control thyrotoxicosis or DM

Cardiac arrhythmia, pulmonary edema, MI, hypotension, hyperinsulinemia, antidiuresis, hypokelemia,

Tachycardia, hyperinsulinemia, hyperglycemia, neonatal hypoglycemia, hypocalcemia, hypotesion, myocardial and septal hypertrophy, MI

Hearne AE, Nagey DA. Therapeutic agents in preterm labor: tocolytic agents. Clin Obstet Gynecol 2000;43:787-801

Magnesium sulfate

Dose CI Maternal SE Fetal SE

4-6 gm bolus then 2-3 gm/hr

Myasthenia gravis

Flushing, lethargy, headache, muscle weakness, diplopia, dry mouth, pulm edema, cardiac arrhythmia

Lethargy, hypotonia, resp. depression, demineralization with prolong use

Hearne AE, Nagey DA. Therapeutic agents in preterm labor: tocolytic agents. Clin Obstet Gynecol 2000;43:787-801

Nifedipine

Dose CI Maternal SE Fetal and neonatal SE

30 mg Loading

Then 10-20 mg q 4-6 hr

Cardiac dis, use caution with renal dis,BP<90/50mmHg,

Avoid use with MgSo4

Flushing, headache, dizziness, Nausea , transient

hypotension

None note as yet

Hearne AE, Nagey DA. Therapeutic agents in preterm labor: tocolytic agents. Clin Obstet Gynecol 2000;43:787-801

Corticosteroid Therapy

• Enhance fetal lung maturation• Rescue therapy?• Betamethasone is superior to Dexamethasone• Regimens:

– Two doses of Betamethasone 12 mg IM q 24 hrs

– Four doses of Dexamethasone 6 mg IMq 12 hrs

• Goal is neonatal sepsis preventionGoal is neonatal sepsis prevention• Not to prevent preterm birthNot to prevent preterm birth

Group B streptococcus prophylaxis

Group B streptococcus prophylaxis

Centers for Disease Control and Prevention, 2002d

Cunningham et al, 23rd Ed Williams Obstetrics

Recommended Management of Preterm

Labor

• Confirmation of preterm labor• GA <34 weeks: corticosteroids are given for

enhancement of fetal lung maturation• GA <34 weeks: reasonable to attempt

inhibition of contractions to delay delivery while given corticosteroid & group B streptococcal prophylaxis

• GA >34 weeks: monitor for labor progression & fetal well-being

Thank You