lecture 9 preterm and postterm delivery

Lecture 9Lecture 9

PRETERM AND POSTTERMPRETERM AND POSTTERMDELIVERYDELIVERY

PRETERM DELIVERYPRETERM DELIVERY

DEFINITION OF TERMSDEFINITION OF TERMSI. AS TO SIZEI. AS TO SIZE Small-for-gestational age / fetal growth restriction / Small-for-gestational age / fetal growth restriction /

intrauterine growth restriction (SGA/IUGR)intrauterine growth restriction (SGA/IUGR)• newborns with birthweight below the 10th percentile newborns with birthweight below the 10th percentile

for gestational age for gestational age

Large-for-gestational age (LGA)Large-for-gestational age (LGA)• birthweight above the 90th percentile birthweight above the 90th percentile

Appropriate-for-gestational age (AGA)Appropriate-for-gestational age (AGA)• newborns with weight between the 10th and 90th newborns with weight between the 10th and 90th

percentiles percentiles II. AS TO AOGII. AS TO AOGPreterm or premature birth Preterm or premature birth • neonates born too early neonates born too early • delivery before 37 completed weeksdelivery before 37 completed weeksTerm Term • 37 – 42 weeks37 – 42 weeksPost termPost term• > 42 weeks> 42 weeks

I.I. Medical and Obstetrical ComplicationsMedical and Obstetrical Complications

• PreeclampsiaPreeclampsia

• Fetal distress Fetal distress

• Fetal growth restrictionFetal growth restriction

• Placental abruptionPlacental abruption

• Fetal deathFetal death

• Spontaneous preterm labor with or Spontaneous preterm labor with or without prematurely ruptured membraneswithout prematurely ruptured membranes

CAUSES OF PRETERM BIRTHCAUSES OF PRETERM BIRTH

II. Threatened AbortionII. Threatened Abortion

• Vaginal bleeding or spotting is associated Vaginal bleeding or spotting is associated with increased incidence of subsequent with increased incidence of subsequent pregnancy loss prior to 24 weeks, preterm pregnancy loss prior to 24 weeks, preterm labor, and placental abruptionlabor, and placental abruption


III. Lifestyle FactorsIII. Lifestyle Factors

1. Cigarette smoking1. Cigarette smoking • Associated with 20 % of low-birthweight Associated with 20 % of low-birthweight

neonates, 8 % of preterm births, and 5 % of neonates, 8 % of preterm births, and 5 % of perinatal deaths perinatal deaths

• 2- to 5-fold risk of preterm prematurely 2- to 5-fold risk of preterm prematurely ruptured membranes, a 1.2- to 2-fold risk of ruptured membranes, a 1.2- to 2-fold risk of preterm delivery, and a 1.5- to 3.5-fold risk preterm delivery, and a 1.5- to 3.5-fold risk of fetal growth restrictionof fetal growth restriction

• increased incidence of ectopic pregnancy, increased incidence of ectopic pregnancy, placental abruption, and placenta previaplacental abruption, and placenta previa


2. inadequate maternal weight gain during 2. inadequate maternal weight gain during pregnancy pregnancy

3. illicit drug 3. illicit drug

4. Other maternal factors: 4. Other maternal factors: • young or advanced maternal age young or advanced maternal age • poverty poverty • short stature short stature • vitamin C deficiency vitamin C deficiency • occupational factors: prolonged walking or occupational factors: prolonged walking or

standing, strenuous working conditions, and standing, strenuous working conditions, and long weekly work hours long weekly work hours


5. Psychological and physical stress - seldom 5. Psychological and physical stress - seldom been formally studied but seem intuitively been formally studied but seem intuitively importantimportant

6. Both stress and higher levels of maternal 6. Both stress and higher levels of maternal serum cortisol have been associated with serum cortisol have been associated with spontaneous preterm birthspontaneous preterm birth

7. significant link between low birthweight 7. significant link between low birthweight and preterm birth in women injured by and preterm birth in women injured by physical abusephysical abuse

8. maternal depression was not associated 8. maternal depression was not associated with birth prior to 35 weekswith birth prior to 35 weeks


IV. Genetic Factors IV. Genetic Factors

• gene for decidual relaxin is one candidate gene for decidual relaxin is one candidate

• Fetal mitochondrial trifunctional protein Fetal mitochondrial trifunctional protein defects or polymorphism in the interleukin-defects or polymorphism in the interleukin-1 gene complex, 1 gene complex, 22-adrenergic receptor, or -adrenergic receptor, or tumor necrosis factor- α (TNF- α) may also tumor necrosis factor- α (TNF- α) may also be involved in preterm membrane rupture be involved in preterm membrane rupture


V. ChorioamnionitisV. Chorioamnionitis

• Infection of the membranes and amnionic Infection of the membranes and amnionic fluid caused by a variety of microorganisms fluid caused by a variety of microorganisms - possible causes of ruptured membranes, - possible causes of ruptured membranes, preterm labor, or bothpreterm labor, or both

• recovery of organisms from the recovery of organisms from the

chorioamnion was significantly increased chorioamnion was significantly increased with spontaneous preterm laborwith spontaneous preterm labor


1.1. Risk-Scoring SystemsRisk-Scoring Systems• Not effectiveNot effective

2. Prior Preterm Birth2. Prior Preterm Birth• strongly correlates with subsequent preterm strongly correlates with subsequent preterm

laborlabor• risk of recurrent preterm delivery for women risk of recurrent preterm delivery for women

whose first delivery was preterm was whose first delivery was preterm was increased threefold compared with that of increased threefold compared with that of women whose first neonate was born at term women whose first neonate was born at term

• More than a third of women whose first two More than a third of women whose first two newborns were preterm subsequently newborns were preterm subsequently delivered a third preterm newborn delivered a third preterm newborn

IDENTIFICATION OF WOMEN AT RISK IDENTIFICATION OF WOMEN AT RISK FOR SPONTANEOUS PRETERM LABORFOR SPONTANEOUS PRETERM LABOR

3. Incompetent Cervix3. Incompetent Cervix• recurrent, painless cervical dilatation and recurrent, painless cervical dilatation and

spontaneous midtrimester birth in the absence spontaneous midtrimester birth in the absence of spontaneous membrane rupture, bleeding, of spontaneous membrane rupture, bleeding, or infection or infection

4. Cervical Dilatation4. Cervical Dilatation• Asymptomatic cervical dilatation after Asymptomatic cervical dilatation after

midpregnancy has gained attention as a risk midpregnancy has gained attention as a risk factor for preterm delivery, although some factor for preterm delivery, although some clinicians consider it to be a normal anatomical clinicians consider it to be a normal anatomical variant, particularly in parous women variant, particularly in parous women

• Recent studies suggested that parity alone is Recent studies suggested that parity alone is not sufficient to explain cervical dilatation not sufficient to explain cervical dilatation discovered early in the third trimesterdiscovered early in the third trimester


ULTRASONOGRAPHIC MEASUREMENT ULTRASONOGRAPHIC MEASUREMENT OF CERVICAL LENGTHOF CERVICAL LENGTH

• mean cervical length at 24 weeks was about 35 mean cervical length at 24 weeks was about 35 mm, and those women with progressively shorter mm, and those women with progressively shorter cervices experienced increased rates of preterm cervices experienced increased rates of preterm birth birth

• women with a previous preterm birth (< 32 weeks) women with a previous preterm birth (< 32 weeks) should undergo, on her next pregnancy, an should undergo, on her next pregnancy, an ultrasound examination of cervical length between ultrasound examination of cervical length between 16 to 24 weeks AOG; a shortened cervix ( < 16 to 24 weeks AOG; a shortened cervix ( < 25mm ) correlates with another subsequent 25mm ) correlates with another subsequent preterm birth before 35 weekspreterm birth before 35 weeks

• the value of cervical length to predict birth the value of cervical length to predict birth before 35 weeks is apparent only in women before 35 weeks is apparent only in women at high risk for preterm birthat high risk for preterm birth

• routine cervical ultrasonography currently routine cervical ultrasonography currently

has no role in the screening of normal-risk has no role in the screening of normal-risk pregnant women pregnant women

• efficacy of cerclage for women with only a efficacy of cerclage for women with only a shortened cervical length with no history of shortened cervical length with no history of recurrent midpregnancy loss is inconclusive recurrent midpregnancy loss is inconclusive

ULTRASONOGRAPHIC MEASUREMENT ULTRASONOGRAPHIC MEASUREMENT OF CERVICAL LENGTHOF CERVICAL LENGTH

5. Signs and Symptoms5. Signs and Symptoms

• painful or painless uterine contractions painful or painless uterine contractions • pelvic pressure pelvic pressure

• menstrual-like crampsmenstrual-like cramps

• watery vaginal dischargewatery vaginal discharge

• pain in the low backpain in the low back


6. Ambulatory Uterine Monitoring6. Ambulatory Uterine Monitoring

• an external tocodynamometer is belted an external tocodynamometer is belted around the abdomen and connected to an around the abdomen and connected to an electronic waist recorder electronic waist recorder

• Uterine activity is transmitted via telephone Uterine activity is transmitted via telephone dailydaily

• Women are educated concerning signs and Women are educated concerning signs and

symptoms of preterm labor, and clinicians are symptoms of preterm labor, and clinicians are kept apprised of their progresskept apprised of their progress

• ACOG concluded that the use of this ACOG concluded that the use of this expensive, bulky, and time-consuming system expensive, bulky, and time-consuming system does not reduce the rate of preterm birthdoes not reduce the rate of preterm birth


7. Fetal Fibronectin7. Fetal Fibronectin

• glycoprotein produced in 20 different glycoprotein produced in 20 different molecular forms by hepatocytes, molecular forms by hepatocytes, fibroblasts, and endothelial cells, and by fibroblasts, and endothelial cells, and by fetal amnion fetal amnion

• Present in high concentrations in maternal Present in high concentrations in maternal blood and in amnionic fluid which play a role blood and in amnionic fluid which play a role in intercellular adhesion during in intercellular adhesion during implantation and in the maintenance of implantation and in the maintenance of placental adhesion to the decidua placental adhesion to the decidua

• detected in cervicovaginal secretions in detected in cervicovaginal secretions in women who have normal pregnancies with women who have normal pregnancies with intact membranes at term, and it appears to intact membranes at term, and it appears to reflect stromal remodeling of the cervix reflect stromal remodeling of the cervix prior to laborprior to labor


7. Fetal Fibronectin7. Fetal Fibronectin

• fibronectin detection in cervicovaginal fibronectin detection in cervicovaginal secretions prior to membrane rupture was a secretions prior to membrane rupture was a possible marker for impending preterm possible marker for impending preterm labor labor

• measured using an enzyme-linkedmeasured using an enzyme-linked

• immunosorbent assayimmunosorbent assay

• values exceeding 50 ng/mL are considered values exceeding 50 ng/mL are considered positivepositive

• positive value for cervical or vaginal fetal positive value for cervical or vaginal fetal fibronectin assay, as early as 8 to 22 weeks fibronectin assay, as early as 8 to 22 weeks - powerful predictor of subsequent preterm - powerful predictor of subsequent preterm birthbirth


8. Bacterial Vaginosis8. Bacterial Vaginosis

• not an infection, a condition in which the not an infection, a condition in which the normal, hydrogen peroxide–producing normal, hydrogen peroxide–producing lactobacillus-predominant vaginal flora is lactobacillus-predominant vaginal flora is replaced with anaerobes, replaced with anaerobes, Gardnerella Gardnerella vaginalis, Mobiluncusvaginalis, Mobiluncus species, and species, and Mycoplasma hominisMycoplasma hominis

• associated with spontaneous abortion, associated with spontaneous abortion, preterm labor, preterm ruptured preterm labor, preterm ruptured membranes, chorioamnionitis, and amnionic membranes, chorioamnionitis, and amnionic fluid infectionfluid infection

• may precipitate preterm labor by a may precipitate preterm labor by a mechanism similar to that proposed for mechanism similar to that proposed for amnionic fluid infection amnionic fluid infection

• screening and treatment have not been screening and treatment have not been shown to prevent preterm birth shown to prevent preterm birth


9. Lower Genital Tract Infection9. Lower Genital Tract Infection• Currently, screening and treatment to Currently, screening and treatment to

prevent preterm birth in women with either prevent preterm birth in women with either Chlamydia trachomatisChlamydia trachomatis or or Trichomonas Trichomonas vaginalisvaginalis is not recommended is not recommended


10. Salivary Estriol10. Salivary Estriol• increased maternal salivary estriol increased maternal salivary estriol

concentration and subsequent preterm birthconcentration and subsequent preterm birth

11. Periodontal Disease11. Periodontal Disease• Oral bacteria - Oral bacteria - Fusobacterium nucleatumFusobacterium nucleatum

and and CapnocytophagaCapnocytophaga species, have been species, have been associated with upper genital tract infection associated with upper genital tract infection in pregnant women in pregnant women

• sevenfold risk of preterm birth sevenfold risk of preterm birth


INFECTIONS RELATED TO PRETERM INFECTIONS RELATED TO PRETERM LABORLABOR

INFECTION ETIOLOGY DIAGNOSTIC FEATURES MANAGEMENT

Bacterial vaginosis

Gardnerella vaginalis, Mobiluncus species, and Mycoplasma hominis

-Vaginal pH > 4.5-Homogenous vaginal discharge- Amine odor when vaginal secretions are mixed with KOH- Vaginal epithelial cells heavily coated with bacilli “clue cells”- Gram staining of vaginal secretions show few white cells along with mixed flora as compared with the normal predominance of lactobacilli

Metronidazole 500 mg BID for 7 days

Trichomoniasis and Candida Vaginitis

Trichomonas vaginalis - demonstration of Trichomonads by wet mount of vaginal secretions; Trichomondas are identified most accurately by culture using Diamond medium, Direct immunoflorescent, Monoclonal Ab staining is sensitive and specific alternative

- Routine screening and treatmetn for this condition cannot be recommended- Metronidazole 250 mg TID for 7 days- Miconazole, Clotrimazole and nystatin are effective for vaginal candidiasis

Lower genital tract infection

Chlamydia trachomatis

- Genitourinary Chlamydial infection at 24 weeks but not at 28 weeks detected via ligase chain reaction assay was associated with a 2-fold increase in subsequent spontaneous preterm birth

Erythromycin 500 mg PO QID for 7 days


PeriodontitisPeriodontitis Fusobacterium Fusobacterium nucleatumnucleatum and and CapnocytophagaCapnocytophaga speciesspecies

Teeth cleaning Teeth cleaning and polishing; and polishing; deep root deep root scaling and scaling and planning plus planning plus metronidazole metronidazole


MANAGEMENT OF PRETERM LABORMANAGEMENT OF PRETERM LABOR

I. PRETERM RUPTURED MEMBRANESI. PRETERM RUPTURED MEMBRANES

• A history of vaginal leakage of fluid should A history of vaginal leakage of fluid should prompt a sterile speculum examination to prompt a sterile speculum examination to visualize gross vaginal pooling of amnionic visualize gross vaginal pooling of amnionic fluid, clear fluid from the cervical canal, or fluid, clear fluid from the cervical canal, or both both

• Confirmation by ultrasonographic Confirmation by ultrasonographic examination to assess amnionic fluid examination to assess amnionic fluid volume; to identify the presenting part; and volume; to identify the presenting part; and if not previously determined, to estimate if not previously determined, to estimate gestational agegestational age

After confirmation of ruptured membranes, After confirmation of ruptured membranes, the following steps are taken:the following steps are taken:

1.1. Cervical dilatation and effacement are Cervical dilatation and effacement are estimated visually during a sterile estimated visually during a sterile speculum examinationspeculum examination

2. If < 34 weeks, if there are no maternal or 2. If < 34 weeks, if there are no maternal or fetal indications for delivery, the woman fetal indications for delivery, the woman and her fetus are initially observed in the and her fetus are initially observed in the labor unit. Broad-spectrum parenteral labor unit. Broad-spectrum parenteral antimicrobials are begun to prevent antimicrobials are begun to prevent chorioamnionitis. Fetal heart rate and chorioamnionitis. Fetal heart rate and uterine activity are monitored for cord uterine activity are monitored for cord compression, fetal compromise, and early compression, fetal compromise, and early labor.labor.


3. If < 34 weeks, betamethasone (two 12-mg 3. If < 34 weeks, betamethasone (two 12-mg doses intramuscularly 24 hours apart) or doses intramuscularly 24 hours apart) or dexamethasone (6 mg intramuscularly dexamethasone (6 mg intramuscularly every 12 hours for four doses) is givenevery 12 hours for four doses) is given

4. If the fetal status is reassuring, and if labor 4. If the fetal status is reassuring, and if labor does not ensue, the woman is usually does not ensue, the woman is usually transferred to an antepartum unit and transferred to an antepartum unit and observed for labor, infection, or fetal observed for labor, infection, or fetal jeopardy jeopardy


• For pregnancies 34 weeks or beyond, if For pregnancies 34 weeks or beyond, if labor does not begin spontaneously, then it labor does not begin spontaneously, then it is induced with intravenous oxytocin unless is induced with intravenous oxytocin unless contraindicated. Cesarean delivery is contraindicated. Cesarean delivery is performed for usual indications, including performed for usual indications, including failed induction of laborfailed induction of labor

• During labor or induction, a parenteral During labor or induction, a parenteral antimicrobial is given for prevention of antimicrobial is given for prevention of group B streptococcal infectiongroup B streptococcal infection


PRETERM LABOR WITH INTACT FETAL PRETERM LABOR WITH INTACT FETAL MEMBRANESMEMBRANES

DiagnosisDiagnosis

Criteria to document preterm labor:Criteria to document preterm labor:

• Contractions of four in 20 minutes or eight Contractions of four in 20 minutes or eight in 60 minutes plus progressive change in in 60 minutes plus progressive change in the cervixthe cervix

• Cervical dilatation greater than 1 cmCervical dilatation greater than 1 cm

• Cervical effacement of 80 percent or greaterCervical effacement of 80 percent or greater


PRETERM LABOR WITH INTACT FETAL PRETERM LABOR WITH INTACT FETAL MEMBRANESMEMBRANES

• managed the same as for those with managed the same as for those with preterm ruptured membranes preterm ruptured membranes

• The cornerstone of treatment is to avoid The cornerstone of treatment is to avoid delivery prior to 34 weeks, if possibledelivery prior to 34 weeks, if possible

1.1. Amniocentesis to detect infection (not Amniocentesis to detect infection (not usually indicated)usually indicated)

2.2. Steroid therapy to enhance fetal lung Steroid therapy to enhance fetal lung maturationmaturation

3.3. Thyrotropin-Releaasing hormone for fetal Thyrotropin-Releaasing hormone for fetal lung maturationlung maturation

4. Antenatal Phenobarbital and Vitamin K – 4. Antenatal Phenobarbital and Vitamin K – combination is not recommended for the combination is not recommended for the prevention of neonatal intraventricular prevention of neonatal intraventricular hemorrhage hemorrhage


INTERVENTIONS TO DELAY PRETERM INTERVENTIONS TO DELAY PRETERM BIRTHBIRTH

1.1. Antimicrobials – not recommended for the Antimicrobials – not recommended for the sole purpose of preventing deliverysole purpose of preventing delivery

2. Emergency cerclage2. Emergency cerclage

3. Treatment for bacterial vaginosis3. Treatment for bacterial vaginosis

INHIBITION OF PRETERM LABORINHIBITION OF PRETERM LABOR

1.1. Bed restBed rest

2. Hydration and sedation2. Hydration and sedation

3. Beta adrenergic receptor agonist3. Beta adrenergic receptor agonist RitodrineRitodrine Terbutaline, IsoxuprineTerbutaline, Isoxuprine

Beta adrenergic drugsBeta adrenergic drugs Parenteral beta agonists prevent Parenteral beta agonists prevent

preterm birth for at least 48 hours preterm birth for at least 48 hours facilitating maternal transport and facilitating maternal transport and giving of steroidsgiving of steroids

4. Magnesium sulfate4. Magnesium sulfate• Ionic magnesium in a sufficiently high concentration Ionic magnesium in a sufficiently high concentration

can alter myometrial contractilitycan alter myometrial contractility• role is presumably that of a calcium antagonist role is presumably that of a calcium antagonist • Clinical observations are that magnesium in Clinical observations are that magnesium in

pharmacological doses may inhibit laborpharmacological doses may inhibit labor• intravenously administered magnesium sulfate—a 4-intravenously administered magnesium sulfate—a 4-

g loading dose followed by a continuous infusion of 2 g loading dose followed by a continuous infusion of 2 g/hr—usually arrests laborg/hr—usually arrests labor

5. Prostaglandin inhibitors5. Prostaglandin inhibitors (ex. Indomethacin) (ex. Indomethacin)

6. Calcium channel blockers6. Calcium channel blockers • NifedipineNifedipine

7. Atosiban7. Atosiban (oxytocin antagonist) (oxytocin antagonist)

8. Nitric oxide donors8. Nitric oxide donors (nitroglycerin) – not effective (nitroglycerin) – not effective

INHIBITION OF PRETERM LABORINHIBITION OF PRETERM LABOR

The following considerations should be given The following considerations should be given to women in preterm labor:to women in preterm labor:

1.1. Confirmation of preterm labor Confirmation of preterm labor

2. For pregnancies less than 34 weeks in 2. For pregnancies less than 34 weeks in women with no maternal or fetal women with no maternal or fetal indications for delivery, close observation indications for delivery, close observation with monitoring of uterine contractions and with monitoring of uterine contractions and fetal heart rate is appropriate, and serial fetal heart rate is appropriate, and serial examinations are done to assess cervical examinations are done to assess cervical changeschanges

3. For pregnancies less than 34 weeks, 3. For pregnancies less than 34 weeks, glucocorticoids are given for enhancement glucocorticoids are given for enhancement of fetal lung maturationof fetal lung maturation

RECOMMENDED MANAGEMENT OF RECOMMENDED MANAGEMENT OF PRETERM LABORPRETERM LABOR

The following considerations should be given to The following considerations should be given to women in preterm labor:women in preterm labor:

4. For pregnancies less than 34 weeks in women 4. For pregnancies less than 34 weeks in women who are not in advanced labor, some who are not in advanced labor, some practitioners believe it is reasonable to attempt practitioners believe it is reasonable to attempt inhibition of contractions to delay delivery while inhibition of contractions to delay delivery while the women are given glucocorticoid therapy and the women are given glucocorticoid therapy and group B streptococcal prophylaxis group B streptococcal prophylaxis

5. For pregnancies at 34 weeks or beyond, women 5. For pregnancies at 34 weeks or beyond, women with preterm labor are monitored for labor with preterm labor are monitored for labor progression and fetal well-beingprogression and fetal well-being

6. For active labor, an antimicrobial is given for 6. For active labor, an antimicrobial is given for prevention of neonatal group B streptococcal prevention of neonatal group B streptococcal infectioninfection

RECOMMENDED MANAGEMENT OF RECOMMENDED MANAGEMENT OF PRETERM LABORPRETERM LABOR

1.1. LaborLabor

• Continuous electronic monitoring is Continuous electronic monitoring is preferredpreferred

• Fetal tachycardia, especially with ruptured Fetal tachycardia, especially with ruptured membranes, is suggestive of sepsis membranes, is suggestive of sepsis

• Intrapartum acidemia may intensify some Intrapartum acidemia may intensify some of the neonatal complications usually of the neonatal complications usually attributed to preterm deliveryattributed to preterm delivery

2. Prevention of neonatal group B 2. Prevention of neonatal group B Streptococcal infectionsStreptococcal infections

• The American College of Obstetricians and The American College of Obstetricians and Gynecologists, recommend either penicillin Gynecologists, recommend either penicillin G or ampicillin intravenously every 6 hours G or ampicillin intravenously every 6 hours until delivery for women in preterm laboruntil delivery for women in preterm labor

INTRAPARTUM MANAGEMENTINTRAPARTUM MANAGEMENT

3. Delivery3. Delivery• Staff proficient in resuscitative techniques Staff proficient in resuscitative techniques

commensurate with the gestational age of the commensurate with the gestational age of the newborn and fully oriented to any specific problems newborn and fully oriented to any specific problems should be presentshould be present

4. Prevention of neonatal intracranial hemorrhage4. Prevention of neonatal intracranial hemorrhage• Preterm newborns have germinal matrix bleeding that Preterm newborns have germinal matrix bleeding that

can extend to more serious intraventricular can extend to more serious intraventricular hemorrhage hemorrhage

• It was hypothesized that cesarean delivery to obviate It was hypothesized that cesarean delivery to obviate trauma from labor and vaginal delivery might prevent trauma from labor and vaginal delivery might prevent these complications these complications

• This has not been validated by most subsequent This has not been validated by most subsequent studiesstudies

• hemorrhages related to whether or not the fetus had hemorrhages related to whether or not the fetus had been subjected to the active phase of labor, defined been subjected to the active phase of labor, defined as the interval before 5 cm cervical dilatationas the interval before 5 cm cervical dilatation

• avoidance of active-phase labor is impossible in most avoidance of active-phase labor is impossible in most preterm births because the route of delivery cannot preterm births because the route of delivery cannot be decided until the active phase labor is firmly be decided until the active phase labor is firmly establishedestablished

INTRAPARTUM MANAGEMENTINTRAPARTUM MANAGEMENT

POSTTERM DELIVERYPOSTTERM DELIVERY

DEFINITION OF TERMSDEFINITION OF TERMS

• PostmaturePostmature - infant with recognizable clinical - infant with recognizable clinical features indicating a pathologically features indicating a pathologically prolonged pregnancyprolonged pregnancy

• PostdatesPostdates - should be abandoned, because - should be abandoned, because the real issue in many postterm pregnancies the real issue in many postterm pregnancies is "post-is "post-what what dates?“dates?“

• PosttermPostterm or or Prolonged PregnancyProlonged Pregnancy - preferred - preferred expression for an extended pregnancy expression for an extended pregnancy

• ““Postmature" is reserved for a specific Postmature" is reserved for a specific clinical fetal syndromeclinical fetal syndrome

• According to ACOG(1997) : 42 completed According to ACOG(1997) : 42 completed

weeks (294 days) or more from the first day weeks (294 days) or more from the first day of the last menstrual period of the last menstrual period

Postmaturity SyndromePostmaturity Syndrome

Characteristic appearance / Features: • wrinkled, patchy, peeling skin; a long, thin

body suggesting wasting; and advanced maturity because the infant is open-eyed, unusually alert, and appears old and worried-looking

• Skin wrinkling prominent on the palms and soles

• Nails are long

FETAL DISTRESS IN POSTTERM FETAL DISTRESS IN POSTTERM PREGNANCYPREGNANCY

• antepartum fetal jeopardy and intrapartum antepartum fetal jeopardy and intrapartum fetal distress were the consequence of cord fetal distress were the consequence of cord compression associated with compression associated with oligohydramniosoligohydramnios

• one or more prolonged decelerations one or more prolonged decelerations

preceded three fourths of emergency preceded three fourths of emergency cesarean deliveries for fetal jeopardycesarean deliveries for fetal jeopardy

• findings are consistent with cord occlusion findings are consistent with cord occlusion

as the proximate cause of fetal distressas the proximate cause of fetal distress • other correlates found were other correlates found were

oligohydramnios and viscous meconiumoligohydramnios and viscous meconium

FETAL DISTRESS IN POSTTERM FETAL DISTRESS IN POSTTERM PREGNANCYPREGNANCY

Prolonged fetal heart rate deceleration prior to Prolonged fetal heart rate deceleration prior to emergency cesarean delivery in a postterm pregnancy emergency cesarean delivery in a postterm pregnancy with oligohydramnioswith oligohydramnios

FETAL GROWTH RESTRICTION IN FETAL GROWTH RESTRICTION IN POSTTERM PREGNANCYPOSTTERM PREGNANCY

• stillbirths were more common among stillbirths were more common among growth-restricted infants who were growth-restricted infants who were delivered at 42 weeks or beyonddelivered at 42 weeks or beyond

• one third of the postterm stillbirths were one third of the postterm stillbirths were growth restrictedgrowth restricted

• morbidity and mortality were significantly morbidity and mortality were significantly increased in the growth-restricted infantsincreased in the growth-restricted infants

MANAGEMENT OF POSTTERM MANAGEMENT OF POSTTERM PREGNANCYPREGNANCY

• Antepartum interventions are indicated in Antepartum interventions are indicated in cases of postterm pregnanciescases of postterm pregnancies

• When to induce? 41 or 42 weeks?When to induce? 41 or 42 weeks?

• 41 weeks with favorable cervix, induce lab 41 weeks with favorable cervix, induce lab oror

• 41 weeks with unfavorable cervix, 41 weeks with unfavorable cervix, antepartum fetal testingantepartum fetal testing

• 42 weeks, whether the cervix is favorable or 42 weeks, whether the cervix is favorable or not, labor is generally inducednot, labor is generally induced

UNFAVORABLE CERVIXUNFAVORABLE CERVIX

• A cervix that is closed, uneffaced with a A cervix that is closed, uneffaced with a bishop score of bishop score of less than 7less than 7

• women in whom there was no cervical women in whom there was no cervical

dilatation at 42 weeks had a twofold dilatation at 42 weeks had a twofold increased cesarean delivery rate for increased cesarean delivery rate for "dystocia“"dystocia“

• cervical length of cervical length of 3 cm or less3 cm or less determined determined by transvaginal ultrasonography was by transvaginal ultrasonography was predictive of successful inductionpredictive of successful induction

• The American College of Obstetricians and The American College of Obstetricians and Gynecologists (1997) has concluded that Gynecologists (1997) has concluded that prostaglandin gel can be used safely in prostaglandin gel can be used safely in postterm pregnanciespostterm pregnancies

Sweeping or stripping of the membranes:Sweeping or stripping of the membranes:• decreased the frequency of postterm decreased the frequency of postterm

pregnancy. pregnancy. • stripping did not modify the risk for cesarean stripping did not modify the risk for cesarean

delivery and maternal and neonatal infections delivery and maternal and neonatal infections were not increasedwere not increased

Station of the vertexStation of the vertex is important in predicting is important in predicting successful postterm induction. successful postterm induction.

UNFAVORABLE CERVIXUNFAVORABLE CERVIX

Table 37–3. Evaluation and Management of Postterm Pregnancy

1. Postterm pregnancy is defined as a pregnancy that has extended to or beyond 42 completed weeks.

2. Women with a postterm gestation who have an unfavorable cervix can either undergo labor induction or be managed expectantly.

3. Prostaglandin can be used for cervical ripening and labor induction.

4. Delivery should be effected if there is evidence of fetal compromise or oligohydramnios.

5. It is reasonable to initiate antenatal surveillance between 41 and 42 weeks despite lack of evidence that monitoring improves outcomes.

6. A nonstress test and amnionic fluid volume assessment should be adequate, although no single method has been shown to be superior.

7. Many recommend prompt delivery in a woman with a postterm pregnancy, a favorable cervix, and no other complications.

From the American College of Obstetricians and Gynecologists (2004)

lecture 9 preterm and postterm delivery

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