Preterm labor and Post-term delivery

1. Preterm labor and Post-term delivery E.Naghshineh M.D

2. It is estimated that 50% of all major neurologic handicaps in children result from premature births.

3. Average gestational period= 280±14days • Term labor= 37-42 weeks • Preterm labor= 20-37 weeks

4. Activation of the parturition process results in: • membrane activation • Cervical ripening an increase in myometrial responsiveness to endogenous and exogenous signals.

5. Initiating events: • Decidual hemorrhage (abruption) • Mechanical factors (over distention of uterus, cervical incompetence) • Hormonal changes (fetal or maternal stress) • Sub clinical/clinical infection (1/3 –earliest GA)

6. Hormonal • withdrawal of the uterine inhibitor hormone progesterone In Humans: no great increase in cortisol from the fetal adrenal gland before labor nor has a dramatic decrease in progesterone

7. Oxytocin Oxytocin is a universal initiator of labor are its ability to induce labor when given exogenously, and the increase in blood levels that accompanies labor in most species.

8. Oxytocin levels are higher in umbilical artery blood than in umbilical vein or maternal blood . . .

9. The fetus is a source of oxytocin production • The concentration of oxytocin receptors is a major reason for increased contractility of the uterus and release during labor.

10. Prostaglandins • Cytokines

11. INFECTION • symptomatic nongenital infections , such as acute pyelonephritis and pneumonia

12. hypothesis microbes or their products such as endotoxin enter the uterine cavity during pregnancy, most commonly ascending from the lower genital tract. Blood-borne infection from a nongenital focus occurs less commonly.

13. Microbes or their products then interact, most likely with the decidua or possibly with the membranes, producing prostaglandins or directly leading to uterine muscle contraction. This interaction is most likely mediated through a cytokine cascade. As a result, there is cervical dilation, entry of more microbes into the uterus, and continuation of "the viscous cycle" resulting in premature birth.

14. subclinical infection • 1.The prevalence of histologicchorioamnionitis is increased among preterm births

15. Clinical infection • 2.Clinical infections is increased in mothers and neonates after preterm birth. • Sepsis and meningitis are increased 3 to 10 fold in preterm infants. .

16. 3.There are associations of preterm birth with various maternal lower genital infections or microbes. • Active chlamydial infection • Heavy GBS colonization • Trichomonas vaginalis

17. 4.Positive cultures of the amniotic fluid/membranes/decidua are found in some patients in premature labor.

18. The most widely discussed route of upper genital tract infection in preterm labor is an ascending path through the vagina and cervix

19. EPIDEMIOLOGY OF PRETERM LABOR • Currently, 11.8% of women deliver preterm. • The vast majority of preterm deliveries are a result of preterm labor (50%), premature rupture of the Membranes (33%), or cervical incompetence.

20. Major preterm labor risk factors Prior preterm labor 6-8X Multiple gestation 6-8X African-American race 3.3X Low socioeconomic status 1.9-2.6 X

21. Minor preterm labor risk factors Modifiable risksNonmodifiable risks Poor maternal weight gain Extremes of age (<17 or >40) Physically demanding work Prior multiple abortions Smoking History of DES exposure Anemia History of uterine abnormality Bacteriuria Short stature Bacterial vaginosis Low prepregnancy weight Maternal systemic infections : pyelonephritis

22. Risk Scoring Systems • Contraction Monitoring • Salivary Estriol • Screening for Bacterial Vaginosis • Fetal Fibronectin • Cervical Evaluation • a history consistent with cervical incompetence • PPROM prior to 32 weeks gestation • history of cold-knife conization • diethylstilbestrol exposure uterine • uterine anomaly

23. PRETERM LABOR DEFINITION • Uterine contractions (>4 contractions per 20 minutes) and cervical dilation (>2 cm in a nullipara and >3 cm in a multipara) and cervical effacement (>80%) or uterine contractions and cervical change.

24. TREATMENT OF PRETERM LABOR • Hormone treatment • Alcohol treatment • Beta-mimetics • MgSO 4 • Antiprostaglandins • Anti-oxytocics • Ca channel blockers

25. Absolute contraindications to tocolytic therapy Severe preeclampsia Severe abruptio Severe bleeding any cause Frank chorioamnionitis Fetal death Fetal anomaly incompatible with life Severe fetal growth restriction Mature lung studies Maternal cardiac arrythmias

26. Relative contraindications to tocolytic therapy Mild chronic hypertension Mild abruptio Stable previa Maternal cardiac disease Hyperthyroidism Uncontrolled diabetes mellitus Fetal distress Fetal anomaly Mild intrauterine growth restriction Cervix >4 cm

27. Maternal side effects related to MgSO4 Common Flushing Sense of warmth Headache Nystagmus Nausea Dizziness Lethargy Serious Pulmonary edema Neuromuscular blockage Osteopenia

28. Prolonged Pregnancy • Postterm pregnancy, is one that has lasted longer than 42 weeks or 294 days beyond the first day of the last menstrual period

29. Postdatism implies pregnancy lasting beyond the estimated due date at 40weeks. • Postdatism: 3% to 12% of all pregnancies. • The term "postmature" is reserved for the pathologic syndrome in which the fetus experiences placental insufficiency and resultant intrauterine growth restriction.

30. Prolonged pregnancies are at risk for macrosomia resulting in shoulder dystocia and fetal injury, oligohydramnios, meconium aspiration, intrapartum fetaldistress, and stillbirth. • Maternal risks include trauma, hemorrhage, and labor abnormalities

31. The most common cause of a prolonged pregnancy is inaccurate dating. • Early ultrasound dating • Placental sulfatase deficiency is an X-linked disorder that affects male fetuses.

32. Maternal risk factors for prolonged pregnancy include; • primiparity, • previous prolonged pregnancy, • young maternal age.

33. AMNIOTIC FLUID • Commonly used ultrasound techniques include the four-quadrant AFI and the largest vertical pocket

34. ANTENATAL TESTING • CST, NST, and BPP

35. THE FETUS • Postmature infant was characterized by peeling, parchmentlike skin, wasted appearance and meconium staining of skin, membranes, and the cord

36. The postmaturity syndrome described by Clifford is seen in only a small percentage of prolonged pregnancies. • By far the most common complication is macrosomia resulting in dystocia with associated brachial plexus injuries and fractures.

37. MANAGEMENT • The risk of stillbirth increases as gestational age • Induction and expectant management have similar outcomes, and either is suitable for managing the uncomplicated prolonged gestation.

38. PREVENTION • Separation of the membranes from the lower uterine segment (membranesweeping) is a safe and inexpensive method of inducing labor, although its effectiveness is most likely operator-dependent.

39. INDUCTION OF LABOR • In the presence of a favorable cervix, induction after 41 weeks is reasonable.

40. Towards a safe motherhood