PRETERM LABOUR

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Presented by :

Dr. Khushbu

PRETERM LABOUR

Preterm labour (PTL) is defined as the onset of

labour after the viability i.e. 20 weeks and

before 37 completed weeks of gestation

regardless of birth weight and with intact fetal

membranes.

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It occurs in 6-10% of all deliveries.

Burden of Illness:Significance

• accounts for 85% of perinatal morbidity and mortality.

Major short term problems in preterm infants include:

• Respiratory distress syndrome
• Bronchopulmonary dysplasia
• Necrotizing enterocolitis
• Immune deficiency
• Intraventricular hemorrhage
• Retinopathy of prematurity
• Patent ductus arteriosus

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• Hypoglycemia

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Long term problems include:

• Reactive airway disease
• Asthma
• Cholestasis
• Cerebral palsy and Cerebral atrophy
• Hydrocephalus
• Neurodevelopmental delay
• Hearing loss
• Blindness and Retinal detachment

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• Pulmonary hypertension
• Hypertension in adulthood
• Increased insulin resistance

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ETIOLOGY

In about 50 % , the cause of preterm labour is not

known. Often it is multifactorial.

Spontaneous preterm birth:

1. History of previous preterm delivery
2. History of genital tract colonization and infection
1. Bacteriuria or recurrent UTI
2. STDs
3. Spontaneous or induced abortion

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Genital tract infection

1. In women in spontaneous preterm labour and intact membranes, lower genital tract flora are commonly found in the amniotic fluid, placenta and membranes.
2. The flora include Ureaplasma urealyticum, Mycoplasma hominis, Fusobacterium species, Gardnerella vaginalis and Bacteroides species.
3. Evidence of infection is less common after 34 wks

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BACTERIAL VAGINOSIS

• In this condition lactobacillus predominant vaginal flora is replaced with gram negative anaerobes eg.Gardnerella vaginalis, Mobiluncus , Prevotella and Mycoplasma hominis.

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• BV is associated with two fold increased risk of spontaneous preterm birth.

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• Despite the association antibiotic eradication of BV does not consistently reduce the risk of preterm birth.

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3. Pregnancy following ART:

• Multifetal gestation
• Microbial colonization of the upper genital tract
• Increased rate of birth defects
• Side effects of superovulation

4. Cigarette smoking

5. Poor nutrition and Low prepregnancy BMI< 19.8 kg/sq m

6. Maternal stress

7. Periodontal disease

8. Uterine anomaly

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9. Cervical factors

1. Cervical surgeries e.g. conization and LEEP
2. Short cervical length

10. African and American women have increased risk for preterm birth

11. Systemic infections like acute appendicitis, pyelonephritis

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Indicated preterm birth

1. Pre eclampsia
2. APH
3. Polyhydramnios
4. Diabetes
5. Fetal distress and IUGR
6. Birth defects
7. IUD

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Idiopathic (Majority):

Premature effacement of the cervix with irritable uterus and early engagement of the head are often associated. In the absence of any complicating factors, it is presumed that there is premature activation of the same systems involved in initiating labour at term.

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CHORIOAMNIONITIS

Acute chorioamnionitis

• Acute/overt chorioamnionitis occurs in 10% patients with established preterm labor.

Diagnosis:

- Fever (maternal temperature > 100.4 F) and two or more of following –

1. Maternal tachycardia(>100 bpm).
2. Fetal tachycardia(>160 bpm).
3. Uterine tenderness.
4. Foul odour of amniotic fluid.
5. Maternal leukocytosis(>15000/cumm).
6. CRP> 2.7 mg/dl

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Subclinical chorioamnionitis

• occurs in women in PTL without evidence of overt infection.
• Determination of plasma CRP concentration is useful.
• Amniocentesis is recommended when CRP is more than 1.6 mg/dl for gram stain, cell count, IL 6 concentration and culture to diagnose subclinical chorioamnionitis.

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ETIOPATHOGENESIS

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all acts on

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PGE2, F2α, TxA2, Leukotrienes, Proteases ↑

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Myometrial contraction and cervical ripening PTL

Activation of fetal HPA axis

CRH, cortisol ↑

Choriodecidual bacterial colonisation

TNF, IL-1,6,8↑

Abnormal uterine distension

Gap junction, PG synthetase, IL8↑

Chorion, amnion and decidua

PREDICTORS OF PTL

• Regular uterine contractions of four in 20 mins or eight in 60 mins and each should last > 40 sec
• Per vaginum examination to assess status of cervix

- Cervical dilatation > 1 cm

• Cervical effacement of 80% or greater
• TV – US to determine cervical length
• Detection of fetal fibronectin in cervico vaginal secretions

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• Advanced preterm labor – cervix > 80% effaced and > 3 cm dilated
• Early preterm labour – cervix > 80% effaced and >1 but < 3 cm dilated
• Threatened PTL – Cx < 80% effaced, < 1 cm dilated and cervical length < 2.5 cm on TV-US
• False/ spurious labor – cervical length > 2.5 cm

SYMPTOMS AND SIGNS

• Menstrual like cramps
• Abdominal cramping with or without diarrhoea
• Low dull backache
• Pelvic pressure
• Vaginal discharge – mucous, watery or bloody

INVESTIGATIONS

• Complete blood count
• Urine for routine analysis, culture and sensitivity test
• USG to assess EFW, presentation, gestational age, placental location, AFI, fetal or uterine anomalies. Cervical length can also be examined.
• Cervicovaginal swab for culture and FFN

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FETAL FIBRONECTIN

• It is valuable test to determine the risk of preterm delivery.
• It is glycoprotein that acts as cement between fetal membranes and decidua.
• It is normally present in cervicovaginal secretions before 22 wks and after 37 wks
• Presence of fibronectin between 24 – 34 wks is predictor of PTL.

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• If the FFN test is positive > 50 ng/ml, the likelihood of preterm delivery in the following 2 wks is approx. 35%

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• Sexual intercourse, speculum or digital pelvic examinations and endovaginal ultrasound interfere with accuracy of the test.

PREVENTION

1. Identification of subjects at risk

• To determine woman’s risk on basis of socioeconomic & past medical & reproductive risk factors
• Measurement of cervical length & FFN

2. Effective measurements to avoid abnormal outcome

• Bed rest – patient is to lie in left lateral position
• Nutritional supplements – Omega 3 polyunsaturated fatty acids reduce levels of proinflammatory cytokines
• Periodontal care
• Antibiotics
• Cervical cerclage

• Progesterone
• It is involved in maintenance of pregnancy.
• It reduces gap junction formation and acts as oxytocin antagonism leading to smooth muscle relaxation, maintenance of cervical integrity and anti-inflammatory effect
• Progesterone has been recommended for pregnant women with prior preterm birth.
• Dose – 17 hydroxy progesterone caproate 250 mg IM weekly

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MANAGEMENT

• 1.
• To arrest PTL if not contraindicated

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• 2.
• Appropriate management of labour

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• 3.
• Effective neonatal care

MANAGEMENT

1. Bed rest
2. Adequate hydration

TOCOLYSIS:

Contraindications to tocolysis:

• Gestation more than 34 weeks
• Suspected fetal asphyxia
• Chorioamnionitis
• IUD or lethal anomaly

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Maternal indication

• Uncontrolled diabetes
• Severe anaemia
• Cardiac disease
• Severe preeclampsia or eclampsia
• Haemorrhage

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TOCOLYTIC DRUGS

Calcium channel blockers

- Use of CCBs compared with other tocolytic agents associated with reduction in number of

women giving birth within 7 days of receiving

treatment and before 34 weeks of gestation.

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- Decreased incidence of neonatal RDS, NEC, IVH

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• Nifedipine:
• First line tocolytic agent
• It causes smooth muscle relaxation
• 30 mg orally F/b 20 mg every 6 hrs.
• Hypotension and headache are the main maternal side effect

• ß adrenergic agents
• Second choice of drug
• Terbutaline – 5 mg dissolved in 500 ml of RL and started at 5 μg/min and increased gradually by 5 μg/min every 10-20 mins until stoppage of contractions. Max. dose is 30 μg/min
• Ritodrine – 100 μg/min initially then increased by 50 μg/min until contractions stop. Max. dose is 350 μg/min
• Isoxsuprine

• Contraindicated in patients with chorioamnionitis, eclampsia or preeclampsia, uncontrolled insulin dependent diabetes, cardiac disease and hyperthyroidism

• Magnesium sulphate:
• Use of this drug for treatment of PTL originated in observation that it causes decrease in intensity and frequency of contractions in preeclamptic women in labor.
• Administration of mag. sulphate at time of preterm birth before 32 wks to reduce incidence of CP
• Competes for myometrial calcium entry thereby decreases uterine contractility

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Side effects – Neuromuscular toxicity

Pulmonary congestion

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In neonates, there is increased risk of IVH and

hypotonia

Indomethacin

• Prostaglandin synthetase inhibitor that prevents production of PGF2α
• It is not used after 32 wks of gestation
• Dose – 25-50 mg orally F/b 25 mg every 4 or 6 hrs for 3 days

- Indomethacin may be a first-line tocolytic in

associated polyhydramnios.

- Constriction of ductus arteriosus is side effect

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Nitroglycerin

• Smooth muscle relaxant used to achieve uterine relaxation
• It is nitrous oxide donors . NO interacts with enzyme guanylyl cyclase promoting synthesis of guanosine 3-5-monophosphate which activates protein kinases and causes dephosphorylation of myosin light chains and smooth muscle relaxation

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• Diazoxide –
• Inhibits contractility of genitourinary smooth muscle
• Dose – 5 mg/kg given IV slowly in 15-30 mins

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• Atosiban – it is selective oxytocin vasopressin receptor antagonist

• Pulmonary edema is a serious complication of tocolytic treatment. Clinical picture is of respiratory distress, bilateral rales on auscultation and pink frothy sputum.
• During this treatment , pulse oximetry and monitoring of vital signs every 2 hrs is mandatory. Maternal tachycardia above 120 bpm and BP below 100/60 and fever are reasons for discontinuation of treatment

CORTICOSTEROIDS

• Act generally in developing fetus to promote maturation overgrowth.
• Promote surfactant synthesis, increase lung compliance and reduce vascular permeability
• Used to prevent neonatal RDS and IVH
• Mixture of betamethasone phosphate 6 mg and betamethasone acetate 6 mg IM in 2 consecutive doses 24 hrs apart
• Dexamethasone 6 mg IM in 4 consecutive doses 12 hrs apart

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• Steroid treatment is contraindicated in presence of overt infection

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ANTIBIOTICS

• Pregnant women usually screened for GBS colonization at 36 wks of gestation.
• Women should be treated with antibiotics to prevent neonatal GBS infection.
• Drug of choice is penicillin
• Cefazolin is best choice for women with penicillin allergy

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MANAGEMENT DURING LABOUR

First stage

1. Patient is put to bed to prevent early rupture of membranes

2. Ensure adequate fetal oxygenation

3. Epidural analgesia is of choice

4. Labour should be watched by intensive clinical monitoring.

5. In case of delay or anticipating a traumatic vaginal delivery CS is to performed

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Second stage

1. Birth should be gentle and slow
2. Cord is to be clamped immediately to prevent hypervolaemia and hyperbilirubinaemia.

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Abnormality in Shukra and Artava – congenital malformations in fetus

Abnormality in Garbhasaya – uterine anomalies

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Aggravated vayu located in shukra cause premature expulsion of fetus