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Onset of labor before 37 weeks of gestation


Risk Factors

  1. MC cause = idiopathic
  2. Infections (urinary tract, vaginal, dental caries, etc.) Most common organisms responsible for preterm labour. Ureaplasma urealyticum and Gardnerella vaginum causing bacterial vaginosis.
  3. Multiple gestation
  4. Polyhydramnios
  5. Prior pre term delivery
  6. Uterine anomalies
  7. PROM
  8. Fibroids
  9. Smoking
  10. Illicit drug use (especially cocaine)
  11. Low socioeconomic status

Diagnosis of preterm labour:

  1. Regular uterine contractions with or without pain (at least one in every 10 min).
  2. Dilatation (>2 cm) and effacement (80%) of cervix.
  3. Length of cervix (measured by TVS) <2.5 cm and funneling of internal os.
  4. Pelvic pressure, backache and or vaginal discharge or bleeding

Extra Edge:


The possible of preterm delivery when the cervix is <25 mm is 17.8%. so at 24 weeks mean cervical length – 35cm and cut off value for preterm labour – 25 mm.

Risk of Recurrence of Preterm Labor


Birth Outcome

Next Birth S 34 weeks (%)

First birth ≥35 weeks




First birth ≤34 weeks


First and second births s 34 weeks



  1. Fetal fibronectin (FFN) in cervical/vaginal secretions is a predictor of preterm labor. (≥ 50ng/ml)
  2. Increase in maternal salivary estriol is also a predictor.

Extra Edge:

  1. It is a fetal glycoprotein.
  2. Normally it is found in the cervico vaginal dischage before 22 weeks and again after rupture of membranes.
  3. if detected in cervicovaginal secretions prior to rupture of membranes, it indicates disruption of the maternal fetal interface and may be predictive of impending preterm labour.
  4. It is measure by ELISA and a value equal to or exceeding 50ng/ml is considered positive and predictive of preterm delivery.
  5. When the test is negative it reassures that delivery will not occur within next 7 days.
  6. Fetal fibronectin and cervical length <2.5 cm on TVS – best predictors specially in women with prior history of preterm birth.
  1. Steroids (dexamethasone or betamethasone) are given to enhance fetal lung maturity and they also decrease the incidence of intraventricular hemorrhage. They are recommended for all women in preterm labour before 36 week. The effect of treatment is maximal between 24 hr of the first dose and uptil 7 days.
  2. Betamethasone is preferred over dexamethasone, as it also prevents periventricular leukomalacia.
  3. Chorioamnionitis and active infection in mother (e.g., open pulmonary kochs) are the only contraindications for the use of steroids. They can be given to patients of hypertension and diabetes mellitus.
  4. Repeated doses of steroids (weekly) are to be avoided as they are a/w risk of necrotizing enterocolitis, intrauterine growth restriction (IUGR), pulmonary edema, and PIH.
  5. Role of phenobarbital – to prevent intraventricular bleeding in the new born (should be given specially if fetal weight is <2 kg or gestational age <32 weeks) along with tocolysis, bed rest, antenatal corticosteroid & antibiotics.
  6. Cerclage operation are done in cases of recurrent mid trimester abortions and best done around 14 weeks of pregnancy or atlest two weeks earlier than the lowest period of previous wastage, as early as 10th week.

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