Preterm labor

1. PRETERM LABOR
BY : JYOTI SAMRA
ASSISSTANT PROFESSOR

2. DEFINITION
 It is defined by WHO as onset of
labor prior to the completion of 37
weeks of gestation , in a pregnancy
beyond 20 weeks of gestation.
 Preterm labor is considered to be
established if regular uterine
contractions can be documented
atleast 4 in 20 minutes or 8 in 60
minutes with progressive change in
the cervical score in the form of
effacement of 80% or more and
cervical dilatation > 1 cm

3. TYPES OF PRETERM BIRTH
According to WHO gestational age criteria
 Moderate to late preterm : 32 to < 37
weeks
 Very preterm : < 32 weeks
 Extremely preterm : < 28 weeks

4. CAUSES OF PRETERM LABOR
History :
 Recurrent abortion
 Preterm delivery
 Recurrent UTI , asymptomatic bacteriuria
 Artificial reproductive technologies (IVF,
GIFT, surogacy)
 Low socioeconomic conditions
 Smoking habits
 Maternal stress

5. Congenital abnormalities :
 Unicornuate uterus ( only half of the uterus develops ,
resulting in a smaller uterus)
 Bicornuate uterus (occur when mullerian duct don’t fully
fuse resulting in heart shaped uterus instead pear shape)
Mullerian duct= paired structure that develops into female
reproductive organs in females
Pregnancy complications :
 Multiple pregnancy
 APH ( > 24 weeks – upto delivery )
 Pre- eclampsia
 PROM
 Polyhydramnios

6.  Uterine anomalies – cervical incompetence ,
uterine malformations
 Medical and surgical illness – acute fever,
pyelonephritis , appendicitis
 Placental factors – placenta previa , placental
abruption
 Hydramnios due to overdistension

7. Fetal factors :
 Congenital malformation
 Intrauterine death
 Fetal distress
 Intrauterine growth restriction
Iatrogenic : Indicated preterm delivery
due to medical and surgical complications

8. Genetic : Many preterm deliveries are
familial
Idiopathic :
 Early engagement of head and preterm
effacement of the cervix with irritable
uterus.

9. SIGNS AND SYMPTOMS
Signs
 Palpable uterine contractions
 Engagement of the presenting part
 Cervical effacement and dilatation
 Show
 Bulging membranes
 Rupture of membranes

10. Symptoms :
 Painful or painless uterine contractions or
frequent tightening
 Lower abdominal pain or menstrual – like
cramping
 Pain in lower back
 Passage of blood stained vaginal
discharge( show)
 Sensation of pelvic or vaginal pressure
 Increased watery vaginal discharge

11. DIAGNOSTIC EVALUATION
 Pelvic examination
 Routine physical examination
 Vital signs
 Dipstick urine analysis
 Abdominal examination
 Fetal presentation
 Fetal heart and uterine activity
 Vaginal speculum examination
 Cervix
 Membranes status , for swabs
 Digital assessment ( through fingers)

12. ROUTINE INVESTIGATIONS
 Full blood count
 Urine for glucose, proteins , ketones, microscopy,
and culture, urine- analysis , culture and
sensitivity
 Swabs :
 High vaginal swabs for gram staining and
culture, pH and fern test
(diagnostic tool to detect the presence of amniotic
fluid , which can indicate premature rupture of
membranes or onset of labor)

13.  Swab from cervico- vaginal area for fetal
fibronectin ( protein found at the interface
between amniotic sac and uterine lining between
22 – 35 weeks of gestation , it indicates preterm
labor)
 Endocervical swab for Neisseria gonorrhea and
chlamydia trachomatis culture.

14.  Urethral swab in indicated cases.
 CTG for uterine contractions and fetal
heart.
 USG for fetal maturity , fetal anomalies ,
presentation, liquor assessment ,
estimated fetal weight
 TVS assessment for cervical length and
funneling at internal OS
 Serum electrolytes and glucose levels –
when tocolytic agents are to be used

15. MANAGEMENT
 Aim of management of preterm
labor :
1. To prevent asphyxia and birth trauma
2. To prevent preterm onset of labor, if
possible
3. To arrset preterm labor
4. Appropriate management of labor and
duration of labor is usually short
5. Effective neonatal care

16. FIRST STAGE
 The patient lies in bed to prevent early rupture
of membranes as intact membranes may
reduce trauma to the baby.
 In case of anticipated traumatic vaginal
delivery , cesarean delivery can be considered
 The parents should be informed of the likely
outcome by obstetrician and pediatrician
 Strong sedatives and oxytocics should be
avoided

17.  To ensure adequate fetal oxygenation by
giving oxygen to the mother by mask
 Epidural analgesia is of choice
 Labor should be watched by intensive
clinical monitoring if continuous electronic
monitoring is not available
 Repeated digital examination are avoided
 Cesearean delivery is done for obstetric
reasons

18. SECOND STAGE
 All experienced obstetrician should preferably
conduct the delivery in the presence of
pediatrician
 The birth should be gentle and slow to avoid
rapid compression and decompression of head
 Episiotomy is recommended , especially in
primigravidas , to minimize head compression
 Forceps are applied only , if second stage is
delayed and not to act as a protective cage for
the soft preterm head during delivery as once
thought

19.  The cord is to be clamped immediately at
birth to prevent hypervolemia and
hyperbilirubinemia
 The newborn is immediately transferred
to intensive neonatal care unit , with
ventilator facilities under the care of
neonatologist.

20. CESAREAN SECTION
 Routine CS not recommended
 Only for preterm fetuses before 34 weeks
presented by breech
 Lower segment vertical / J shaped incision
made to minimize trauma during delivery.

21. MANAGEMENT

23. PREVENTION
 Avoid tobacco, alcohol , or other substances
while pregnant
 Eat nutritious , well – balanced foods during
pregnancy
 Start prenatal care in the first trimester so
that the care provider can identify health risks
as early as possible

24.  Discuss how to manage health conditions
like diabetes and high blood pressure with
the care provider. Unmanaged health
conditions can lead to preterm birth and
other complications
 Attend all prenatal care appointments
 Reduce the stress level
 Wait at least 18 months between
pregnancies

25. PREVENTION OF PRE TERM LABOR
 Primary care is aimed to reduce the incidence of
preterm labour by reducing to high risk factors
eg.infection.
 Secondary care includes screening tests for early
detection and prophylactic treatment
eg.tocolytics.
 Tertiary care is aimed to reduce the perinatal
morbidity and mortality after the diagnosis
eg.use of corticosteroids.

26. USE OF ANTENATAL
CORTICOSTERIODS
 ACS administered to women at risk for preterm
delivery reduced the incidence and severity of
respiratory distress syndrome and mortality of
offspring
 The positive effect of antenatal corticosteriods is
apparent soon after administeration –maximal
24 to 48 hours later and for upto 1 week but
adequate upto 18 days.
 It should be administered to women at imminent
risk of preterm delivery.

27.  There is a general consensus on administering
antenatal corticosteriods between 24 and 34
weeks of gestation .
 In ideal circumstances , delivery should not occur
within 24 to 48 hours following the
administeration of corticosteriods.

28. BETAMETHASONE OR
DEXAMETHASONE
 These steriods are preferred because they are
less extensively metabolized by the placental
enzymes .
 Doses : Betamethasone : two doses of 12 mg IM
24 hour apart
 Dexamethasone sodium phosphate four doses of 6
mg IM 12 hours can be given as it is equally
effective.

29. MATERNAL SIDE EFFECTS
 Transient hyperglycaemia occurs in many women.
 The steriod effect begins approximately 12 hour
after the first dose and may last for five days .
 Screening for GD , if indicated , should be
performed either before ACS administeration or at
least five days after the first dose.
 The TLC increases by approx. 30 percent within 24
hours after ACS injection , and the lymphocyte
count significantly decreases.
 These changes return to baseline within three days
but may complicate the diagnose of infection.

30. FETAL SIDE EFFECTS
 22 to 34 weeks :
• Reduction in birth weight
• Psychiatric and behaviorol diagnosis , if children
born at term
 35 to 36 weeks :
• Neonatal hypoglycemia
 Before planned CS at term 37- 39 weeks
• Reduce educational attainment at school age
 FHR and biophysical parameters :
• Reduced fetal breathing and body movements can
results in a lower biophysical profile score or non-
reactive NST.

31.  Doppler flow studies : improvement in
umbilical artery end – diastolic flow after ACS
administertaion.

32. INDICATIONS
 True preterm labor
 APH
 Preterm PROM
 Severe pre – eclampsia

33. CONTRAINDICATIONS
 History of fever and lower abdominal pain
 On examination : foul smelling vaginal
discharge, tachycardia and uterine tenderness.
 Fetal tachycardia