Obstetrics-Preterm Birth


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-These are my notes for Chapter 36 of Williams' Obstetrics 23rd Edition

Obstetrics-Preterm Birth

  1. 1. nianderthalNOTESOBSTETRICS:Preterm Birth
  2. 2. PRETERM BIRTH:Definition of Terms*with respect to size, a newborn may be appropriate, small or large forgestational age Appropriate for gestational age-newborns whose birth weight is between 10th and the 90th percentile forgestational age Small for gestational age-newborns whose birth weight is usually below the 10th percentile forgestational age Large for gestational age-newborns whose birth weight is usually above the 90th percentile forgestational age Low birth weight-neonates who are born too small weighing 500 to 2500 grams-Very Low birth weight: 500 to 1500 grams-Extremely Low birth weight: 500 to 1000 grams
  3. 3. PRETERM BIRTH:Definition of Terms*with respect to gestational age, the newbornmay be preterm, term or post-term.Preterm or premature births-neonates who are born too early before 37completed weeks-Late preterm births: delivery at 34 to 36 weeksof gestation
  4. 4. PRETERM BIRTH:Morbidity-a variety of morbidities, largely due to systemimmaturity, are significantly increased ininfants born before 37 weeks’ gestationcompared with those delivered at term-these infants also suffer long-term sequelaesuch as neurodevelopmental disability
  5. 5. PRETERM BIRTH:Threshold of Viability-Births before 26 weeks, especially those weighing lessthan 750 grams are at the current threshold ofvariability-It is considered appropriate not to initiate resuscitationfor infants younger than 23 weeks or those whose birthweight is less than 400 grams-Female gender, singleton pregnancy, corticosteroidsgiven for lung maturation and higher gestational ageimproved the prognosis for infants born at thethreshold of viability
  6. 6. PRETERM BIRTH:Threshold of Viability-From an obstetrical standpoint, all fetal indicationsfor cesarean delivery in more advacedpregnancies are practiced in women at 25 weeks-Cesarean delivery is not offered for fetalindications at 23 weeks-At 24 weeks, cesarean delivery is not offeredunless the fetal weight is estimated at 750 gramsor greater
  7. 7. PRETERM BIRTH:Late Preterm Birth-Infants between 34 to 36 weeks accountapproximately 75% of all preterm births-Approximately 80% of late preterm births weredue to idiopathic spontaneous preterm laboror prematurely ruptured membranes while20% of cases was due to complications suchas hypertension or placental accidents
  8. 8. PRETERM BIRTH:Reasons for Preterm DeliveryThere are four main direct reasons for pretermbirths in the US:1. Delivery for maternal or fetal indications inwhich labor is induced or the infant is deliveredby pre-labor cesarean delivery – 30-35%2. Spontaneous unexplained preterm labor withintact membranes – 40-45%3. Idiopathic preterm premature rupture ofmembranes – 30-35%4. Twins and higher-order multifetal births
  9. 9. PRETERM BIRTH:Reasons for Preterm DeliveryMaternal indications-Most common indications for medical intervention resulting inpreterm birth:1. Preeclampsia2. Fetal distress3. Small for gestational age4. Placental abruption-Less common causes:1. Chronic hypertension2. Placenta previa3. Unexplained bleeding4. Diabetes5. Renal disease6. Rh isoimmunization7. Congenital malformations
  10. 10. PRETERM BIRTH:Reasons for Preterm DeliveryPreterm Prematurely Ruptured Membranes (PPROM)-rupture of membranes before labor and prior to 37 weeks-Factors implicated:1. Pathological mechanisms including intra-amnioticinfection2. Low socioeconomic status3. Low body mass index (BMI) – less than 19.84. Nutritional deficiencies5. Cigarette smoking6. Women with prior PPROM*HOWEVER, most cases of preterm rupture occur without riskfactors or are idiopathic
  11. 11. PRETERM BIRTH:Reasons for Preterm DeliverySpontaneous Preterm Labor-Most commonly, preterm birth, up to 45 % of cases – followsspontaneous labor-Pathogenesis of Preterm labor are implicated on:1. Progesterone withdrawal-as parturition nears, the fetal-adrenal axis becomesmore sensitive to adrenocorticotropic hormone, increasingthe secretion of cortisol  stimulation of 17-α-hydroxylaseactivity  decrease progesterone secretion and increaseestrogen production  increased prostaglandin formation initiates a cascade that culminates in labor
  12. 12. PRETERM BIRTH:Reasons for Preterm Delivery-Pathogenesis of Preterm labor are implicated on:2. Oxytocin initiation-because oxytocin increases the frequency andintensity of uterine contractions, oxytocin is assumed toplay a role in labor initiation3. Decidual activation-seems to be mediated in part by fetal-decidualparacrine system and through localized decrease inprogesterone concentration-decidual activation seems to arise in the context ofintrauterine bleeding or occult intrauterine infection
  13. 13. PRETERM BIRTH:Contributing Factors to Preterm Birth1. Threatened Abortion-Vaginal bleeding in early pregnancy isassociated with increased adverse outcomeslater-Both light and heavy bleeding were associatedwith subsequent preterm labor, placentalabruption, and subsequent pregnancy lossprior to 24 weeks
  14. 14. PRETERM BIRTH:Contributing Factors to Preterm Birth2. Lifestyle Factors-Cigarette smoking, inadequate maternal weight gain, andillicit drug use low-birth weight neonates-Overweight women had lower rates of preterm deliverybefore 35 weeks than women with normal weight-Other maternal factors implicated include young or advancedmaternal age, poverty, short stature, vitamin C deficiency,and occupational factors such as prolonged walking orstanding, strenuous working conditions, and long weeklywork hours-Psychological factors such as depression, anxiety, and chronicstress-Women injured by physical abuse  low birth weight andpreterm birth
  15. 15. PRETERM BIRTH:Contributing Factors to Preterm Birth3. Racial and Ethnic Disparity-Women classified as black, African-American,and Afro-Caribbean are consistently reportedto be at higher risk4. Work During Pregnancy-Working long hours and hard physical labor areprobably associated with increased risk
  16. 16. PRETERM BIRTH:Contributing Factors to Preterm Birth5. Genetic Factors-Immunoregulatory genes may potentiatechorioamnionitis in cases of preterm deliverydue to infection6. Periodontal Disease-Significantly associated with preterm birth—odds ratio 2.83 – but data not consideredrobust enough
  17. 17. PRETERM BIRTH:Contributing Factors to Preterm Birth7. Prior Preterm Birth-A major risk factor for preterm labor is priorpreterm delivery-The risk of recurrent preterm delivery forwomen whose first delivery was preterm wasincreased threefold compared with that ofwomen whose first neonate was born atterm
  18. 18. PRETERM BIRTH:Contributing Factors to Preterm Birth8. Infection-It is hypothesized that intrauterine infections triggerpreterm labor by activation of the innate immunesystem.-Microorganisms elicit release of inflammatory cytokinessuch as interleukins and tumor necrosis factor (TNF), stimulate the production of prostaglandin and/ormatrix-degrading enzymes  Prostaglandinsstimulate uterine contractions, whereas degradationof extracellular matrix in the fetal membranes leadsto preterm rupture of membranes.-Intrauterine infection cause 25-40% of preterm births
  19. 19. PRETERM BIRTH:Contributing Factors to Preterm Birth8. Infection-Potential routes of intrauterine infection:a. Iatrogenic inductionb. Amnionic fluid infectionc. Choriodecidual infectiond. Salpingitis, Villitis or Funisitise. From either uterus, placenta, vagina oreven the fetus
  20. 20. PRETERM BIRTH:Contributing Factors to Preterm Birth8. Infection-Two microorganisms, Ureaplasma urealyticum andMycoplasma hominis, have emerged as importantperinatal pathogens-Bacterial Vaginosis: condition where normal, hydrogenperoxide-producing, lactobacillus-predominant vaginalflora is replaced with anaerobes that include Gardnerellavaginalis, Mobiluncus species, and Mycoplasma hominis- associated with spontaneous abortion, preterm labor,preterm rupture of membranes, chorioamnionitis, andamnionic fluid infection- Causes: exposure to chronic stress, ethnic differences,and frequent or recent douching increased rates of thecondition
  21. 21. PRETERM BIRTH:DiagnosisPatient SymptomsPreviously, The American Academy of Pediatrics andthe American College of Obstetricians andGynecologists (1997) had earlier proposed thefollowing criteria to document preterm labor:-Contractions of four in 20 minutes or eight in 60minutes plus progressive change in the cervix-Cervical dilatation greater than 1 cm-Cervical effacement of 80 percent or greater.*Currently, however, such clinical findings are nowconsidered inaccurate predictors of preterm delivery
  22. 22. PRETERM BIRTH:DiagnosisPatient Symptoms-In addition to painful or painless uterine contractions,these symptoms are empirically associated withimpending preterm birth:-pelvic pressure-menstrual-like cramps-watery vaginal discharge-lower back pain*The signs and symptoms signaling preterm labor,including uterine contractions may appear only within24 hours of preterm labor
  23. 23. PRETERM BIRTH:DiagnosisCervical ChangesCervical Dilatation- Although women with dilatation and effacement in the thirdtrimester are at increased risk for preterm birth, detectiondoes not improve pregnancy outcome- Prenatal cervical examinations are neither beneficial norharmfulCervical Length- Mean cervical length at 24 weeks was approximately 35mm- Women with progressively shorter cervices experiencedincreased rates of preterm birth-Sonographic cervical length, funneling, and prior history ofpreterm birth is correlated with delivery before 35 weeks.
  24. 24. PRETERM BIRTH:Diagnosis Funneling-bulging of the membranes into the endocervical canaland protruding at least 25 percent of the entire cervicallengthIncompetent Cervix Cervical incompetence-a clinical diagnosis characterized by recurrent,painless cervical dilatation and spontaneousmidtrimester birth in the absence of spontaneousmembrane rupture, bleeding, or infection
  25. 25. PRETERM BIRTH:DiagnosisAmbulatory Uterine Monitoring-An external tocodynamometer belted aroundthe abdomen and connected to an electronicwaist recorder allows a woman to ambulatewhile uterine activity is recorded-Women who used home monitoring had asignificant increase in the number ofunscheduled visits, and women with twinshad increased use of tocolytic therapy
  26. 26. PRETERM BIRTH:DiagnosisFetal Fibronectin-Present in high concentrations in maternal blood and inamnionic fluid-Play a role in intercellular adhesion during implantation andin the maintenance of placental adhesion to uterinedecidua-Detected in cervicovaginal secretions in women who havenormal pregnancies with intact membranes at term-Reflect stromal remodeling of the cervix prior to labor-Measured using an enzyme-linked immunosorbent assay, andvalues exceeding 50 ng/mL are considered positive*Positive even as early as 8 to 22 weeks, has beenfound to be a powerful predictor of subsequent pretermbirth
  27. 27. PRETERM BIRTH:PreventionProgesterone Use-American College of Obstetricians and Gynecologists: progesteronetherapy should be limited to women with a documented history of aprevious spontaneous birth at less than 37 weeksCervical Cerclage-Three circumstances when cerclage placement may be used to preventpreterm birth:1. History of recurrent midtrimester losses and who are diagnosed withan incompetent cervix2. Short cervix on sonographic examination3.“Rescue" cerclage, done emergently when cervical incompetence isrecognized in the women with threatened preterm labor
  28. 28. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborAmerican College of Obstetricians andGynecologists: Despite the numerousmanagement methods proposed, the incidence ofpreterm birth has changed little over the past 40years. Uncertainty persists about the beststrategies for managing preterm labor
  29. 29. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborDiagnosis of Preterm Prematurely Ruptured Membranes-A history of vaginal leakage of fluid, either as a continuousstream or as a gush should prompt a speculumexamination to visualize gross vaginal pooling of amnionicfluid, clear fluid from cervical canal, or both.-Confirmation of ruptured membranes is usuallyaccompanied by sonographic examination to:-Assess amnionic fluid volume-Identify the presenting part-Estimate gestational age
  30. 30. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborDiagnosis of Preterm Prematurely RupturedMembranes*basis for frequently used pH testing for rupturedmembranes*blood, semen, antiseptics or bacterial vaginosis arealso alkalinic and can give false-positive resultpHAMNIONIC FLUID 7.1-7.3 (slightly alkalinic)VAGINAL SECRETIONS 4.5-6.0 (acidic)
  31. 31. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborNatural History of Preterm Ruptured Membranes-The time from preterm ruptured membranes todelivery is inversely proportional to thegestational age when rupture occurs
  32. 32. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborExpectant Management-Tocolysis or expectant management did not improveperinatal outcomes-Other considerations with expectant management involvethe use of digital cervical examination and cerclage-Risks of Expectant Management:-No improved neonatal outcomes with expectantmanagement beyond 33 weeks-The volume of amnionic fluid remaining after ruptureappears to have prognostic importance in pregnanciesbefore 26 weeks
  33. 33. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm Labor-Risks of Expectant Management:-Oligohydramnios - defined by the absence of fluidpockets 2 cm or larger*all women with oligohydramnios delivered before25 weeks, whereas 85 percent with adequateamnionic fluid volume were delivered in the thirdtrimester- Lung hypoplasia has a threshold of development of 23weeks or less- Limb compression deformities- Umbilical cord prolapse – increased rate in women withpreterm ruptured membranes and noncephalicpresentation, especially before 26 weeks
  34. 34. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborClinical Chorioamnionitis:- prolonged membrane rupture is associated withincreased fetal and maternal sepsis- If diagnosed, prompt efforts to effect delivery, preferablyvaginally, are initiated- Fever is the only reliable indicator for this diagnosis-Temperature of 38°C or higher accompanying rupturedmembranes implies infection-During expectant management, monitoring for sustainedmaternal or fetal tachycardia, for uterine tenderness, andfor a malodorous vaginal discharge is warranted
  35. 35. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborClinical Chorioamnionitis:- Associated with higher incidence of:- sepsis-respiratory distress syndrome-early-onset seizures-intraventricular hemorrhage-periventricular leukomalacia-vulnerable to neurological injury
  36. 36. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborAntimicrobial Therapy- Only three of 10 outcomes were possibly benefited:1. Fewer women developed chorioamnionitis 2.Fewer newborns developed sepsis3. Pregnancy was more often prolonged 7 days inwomen given antimicrobials*Neonatal survival was unaffected, as was the incidence ofnecrotizing enterocolitis, respiratory distress, orintracranial hemorrhage-Amoxicillin-clavulanate regimen was not recommendedwith an increased incidence of necrotizing enterocolitis
  37. 37. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborCorticosteroids- The National Institutes of Health ConsensusDevelopment Conference (2000) recommended a singlecourse of antenatal corticosteroids for women withpreterm membrane rupture before 32 weeks and inwhom there was no evidence of chorioamnionitis- American College of Obstetricians and Gynecologists:-Single-dose therapy from 24-32 weeks-No consensus regarding treatment between 32 and34 weeks.-Not recommended prior to 24 weeks
  38. 38. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborMembrane Repair-Tissue sealants have been used for a variety ofpurposes in medicine and have becomeimportant in maintaining surgical hemostasis andstimulating wound healing
  39. 39. PRETERM BIRTH:Management of Preterm Rupture ofMembranes and Preterm LaborRecommended ManagementGestational Age Management by the American College of Obstetricians and Gynecologists34 weeks or more -Proceed to delivery, usually by induction of labor-Group B streptococcal prophylaxis is recommended32 weeks to 33completed weeks-Expectant management unless fetal pulmonary maturity is documented-Group B streptococcal prophylaxis is recommended-Corticosteroids—no consensus, but some experts recommend-Antimicrobials to prolong latency if no contraindications24 weeks to 31completed weeks-Expectant management-Group B streptococcal prophylaxis is recommended-Single-course corticosteroids use is recommended-Tocolytics—no consensus-Antimicrobials to prolong latency if no contraindicationsBefore 24 weeks -Patient counseling-Expectant management or induction of labor-Group B streptococcal prophylaxis is not recommended-Corticosteroids are not recommended-Antimicrobials—there are incomplete data on use in prolonging latency
  40. 40. PRETERM BIRTH:Preterm Labor with Intact Membranes-Women with signs and symptoms of preterm laborwith intact membranes are managed much thesame as those with preterm rupturedmembranes-The cornerstone of treatment is to avoid deliveryprior to 34 weeks, if possible
  41. 41. PRETERM BIRTH:Preterm Labor with Intact MembranesAmniocentesis to Detect Infection-The American College of Obstetricians andGynecologists (2003) has concluded that there isno evidence to support routine amniocentesis toidentify infection.
  42. 42. PRETERM BIRTH:Preterm Labor with Intact MembranesCorticosteroid Therapy to Enhance Fetal Lung Maturation- Corticosteroid therapy was effective in lowering the incidence ofrespiratory distress and neonatal mortality rates if birth was delayed forat least 24 hours after initiation of betamethasone- Lower dose had less severe effects on somatic growth without affectingcell proliferation in the fetal brain- American College of Obstetricians and Gynecologists: single-coursetherapy for Corticosteroids- Rescue Therapy: refers to administration of a repeated corticosteroiddose when delivery becomes imminent and more than 7 days haveelapsed since the initial dose*should not be routinely used and reserved for clinical trials-DEXAMETHASON vs BETAMETHASONE: These two drugs werecomparable in reducing the rates of major neonatal morbidities inpreterm infants
  43. 43. PRETERM BIRTH:Preterm Labor with Intact MembranesAntimicrobials- Antimicrobial treatment of women with pretermlabor for the sole purpose of preventing deliveryis generally not recommended- Fetal exposure to antimicrobials in this clinicalsetting was associated with an increased cerebralpalsy rate at age 7 years compared with that ofnon-exposed infants
  44. 44. PRETERM BIRTH:Preterm Labor with Intact MembranesEmergency or Rescue Cerclage- If cervical incompetence is recognized with threatenedpreterm labor, emergency cerclage can be attempted,albeit with an appreciable risk of infection and pregnancyloss- Delivery delay was significantly greater in the cerclagegroup compared with that of bed rest alone—54 versus 24days- Nulliparity, membranes extending beyond the externalcervical os, and cerclage prior to 22 weeks were associatedwith a significantly decreased chance of pregnancycontinuation to 28 weeks or beyond
  45. 45. PRETERM BIRTH:Preterm Labor with Intact MembranesInhibition of Preterm Labor- The American College of Obstetricians andGynecologists: Tocolytic agents do not markedlyprolong gestation, but may delay delivery insome women for at least 48 hours.*May facilitate transport to a regional obstetricalcenter and allow time for administration ofcorticosteroid therapy
  46. 46. PRETERM BIRTH:Preterm Labor with Intact MembranesBed Rest- One of the most often prescribed interventionsduring pregnancy, yet one of the least studied- Bed rest in the hospital compared with bed rest athome had no effect on pregnancy duration inwomen with threatened preterm labor before 34weeks- Bed rest for 3 days or more increasedthromboembolic complications- Significant bone loss in pregnant women prescribedoutpatient bed rest
  47. 47. PRETERM BIRTH:Preterm Labor with Intact Membranesβ-Adrenergic Receptor Agonists- A number of compounds react with β-adrenergicreceptors to reduce intracellular ionized calciumlevels and prevent activation of myometrialcontractile proteins- Ritodrine and terbutaline have been used inobstetrics*only Ritodrine had been approved for pretermlabor by the Food and Drug Administration
  48. 48. PRETERM BIRTH:Preterm Labor with Intact Membranesβ-Adrenergic Receptor Agonists-Ritodrine:-neonates whose mothers were treated with ritodrine for threatenedpreterm labor had lower rates of death and respiratory distress-may lead to Pulmonary edema-withdrawn by manufacturer in 2003- Terbutaline- commonly used to forestall preterm labor- can cause pulmonary edema- terbutaline pumps cause sudden maternal death and a newborn withmyocardial necrosis after the mother used the pump for 12 weeks- oral terbutaline therapy to prevent preterm delivery has also not beeneffective
  49. 49. PRETERM BIRTH:Preterm Labor with Intact MembranesMagnesium Sulfate- Its role is presumably that of a calcium antagonist- Intravenously administered magnesium sulfate—a 4-gram loading dose followed by a continuous infusionof 2 grams/hour—usually arrests labor- Monitored closely for evidence of hypermagnesemia- Parkland Hospital: "Time to Quit" on the use ofmagnesium sulfate for tocolysis on the basis thatthis therapy was ineffective and potentially harmfulto infants
  50. 50. PRETERM BIRTH:Preterm Labor with Intact MembranesMagnesium Sulfate- Neonatal effects:- reduced incidence of cerebral palsy at 3 years- minimize the inflammatory effects of infection- Neuroprotection magnesium from 23 to 32completed weeks*A 6-gram loading dose is followed by an infusion of2 gram per hour for at least 12 hours
  51. 51. PRETERM BIRTH:Preterm Labor with Intact MembranesProstaglandin Inhibitors- Drugs that inhibit prostaglandins have been ofconsiderable interest because prostaglandins areintimately involved in contractions of normal labor- Prostaglandin antagonists act by:-inhibiting prostaglandin synthesis-blocking prostaglandin action on target organs*A group of enzymes collectively termed prostaglandinsynthase is responsible for the conversion of freearachidonic acid to prostaglandins-acetylsalicylate and indomethacin block thissystem
  52. 52. PRETERM BIRTH:Preterm Labor with Intact MembranesProstaglandin Inhibitors-Indomethacin:-administered orally or rectally-50 to 100 mg dose is followed at 8-hour intervalsnot to exceed a total 24-hour dose of 200 mg-Serum concentrations usually peak 1 to 2 hoursafter oral administration,whereas levels after rectaladministration peak slightly sooner.-Limited usese to 24 to 48 hours because ofconcerns of oligohydramnios but is reversible withdiscontinuation of indomethacin.
  53. 53. PRETERM BIRTH:Preterm Labor with Intact MembranesCalcium Channel Blockers-Myometrial activity is directly related to cytoplasmic freecalcium, and a reduction in its concentration inhibitscontractions-Act to inhibit, by a variety of mechanisms, the entry ofcalcium through channels in the cell membrane-Although nifedipine treatment reduced births of neonatesweighing less than 2500 g, significantly more of thesewere admitted for intensive care-Combination of nifedipine with magnesium for tocolysis ispotentially dangerous since nifedipine enhancesneuromuscular blocking effects of magnesium that caninterfere with pulmonary and cardiac function
  54. 54. PRETERM BIRTH:Preterm Labor with Intact MembranesAtosiban-Nonapeptide oxytocin analog is a competitive antagonist ofoxytocin-induced contractions-Failed to improve relevant neonatal outcomes and waslinked with significant neonatal morbidityNitric Oxide Donors-potent smooth-muscle relaxants affect the vasculature, gut,and uterus-Nitroglycerin administered orally, transdermally, orintravenously was not effective or showed no superiorityto other tocolytics-Maternal hypotension was a common side effect
  55. 55. PRETERM BIRTH:Preterm Labor with Intact MembranesSummary of Tocolytic Use for Preterm Labor-Tocolytics stop contractions temporarily but rarelyprevent preterm birth-Although delivery may be delayed long enough foradministration of corticosteroids, treatment doesnot result in improved perinatal outcome-Tocolytic therapy can prolong gestation, but that β-agonists are not better than other drugs and posepotential maternal danger.-There are no benefits of maintenance tocolytictherapy
  56. 56. PRETERM BIRTH:Preterm Labor with Intact MembranesSummary of Tocolytic Use for Preterm Labor-As a general rule, if tocolytics are given, they shouldbe given concomitantly with corticosteroids.-The gestational age range for their use is debatable,but because corticosteroids are not generally usedafter 33 weeks and because the perinatal outcomesin preterm neonates are generally good after thistime, most practitioners do not recommend use oftocolytics at or after 33 weeks
  57. 57. PRETERM BIRTH:Recommended Management ofPreterm LaborThe following considerations should be given to women in preterm labor:1. Confirmation of preterm labor2.For pregnancies less than 34 weeks in women with no maternal or fetalindications for delivery, close observation with monitoring of uterinecontractions and fetal heart rate is appropriate. Serial examinationsare done to assess cervical changes3. For pregnancies less than 34 weeks, corticosteroids are given forenhancement of fetal lung maturation4. Consideration is given for maternal magnesium sulfate infusion for 12to 24 hours to afford fetal neuroprotection
  58. 58. PRETERM BIRTH:Recommended Management ofPreterm LaborThe following considerations should be given to women in preterm labor:5. For pregnancies less than 34 weeks in women who are not in advancedlabor, some practitioners believe it is reasonable to attempt inhibitionof contractions to delay delivery while the women are givencorticosteroid therapy and group B streptococcal prophylaxis.*Although tocolytic drugs are not used at Parkland Hospital, they aregiven at University of Alabama at Birmingham Hospital6. For pregnancies at 34 weeks or beyond, women with preterm labor aremonitored for labor progression and fetal well-being7. For active labor, an antimicrobial is given for prevention of neonatalgroup B streptococcal infection
  59. 59. PRETERM BIRTH:Intrapartum Management-In general, the more immature the fetus, the greater the risks oflabor and delivery-Labor:-Whether labor is induced or spontaneous, abnormalities offetal heart rate and uterine contractions should be sought-Continuous electronic monitoring-Fetal tachycardia, especially with ruptured membranes, issuggestive of sepsis-Intrapartum acidemia (umbilical artery blood pH less than7.0) may intensify some of the neonatal complications usuallyattributed to preterm delivery—more severe respiratorydisease in preterm neonates-Group B streptococcal infections are common and dangerousin the preterm neonate - prophylaxis should be provided
  60. 60. PRETERM BIRTH:Intrapartum Management-Delivery:-In the absence of a relaxed vaginal outlet, anepisiotomy for delivery may be necessary once thefetal head reaches the perineum-Perinatal outcome data do not support routineforceps delivery to protect the "fragile preterm fetalhead"-Staff proficient in resuscitative techniquescommensurate with the gestational age and fullyoriented to any specific problems should be presentat delivery
  61. 61. PRETERM BIRTH:Intrapartum Management-Prevention of Neonatal Intracranial Hemorrhage:-Cesarean delivery did not lower the risk ofmortality or intracranial hemorrhage-Avoidance of active-phase labor is impossible inmost preterm births because the route ofdelivery cannot be decided until the active phaseof labor is firmly established