Prolonged pregnancy

Dr.AHMED JASIM ASS. PROF MBChB.DOG.FICOG

prolonged Pregnancies,( post-term, post-dates):  defined as pregnancies persists beyond 42 completed weeks or more than 294 days from the onset of the last normal menstrual period (LMP).  It occurs in 10% of all pregnancies.  Term is defined as weeks gestation.

 Dating by LMP alone has a tendency to overestimates the gestational age.  The routine use of early ultrasound to calculate gestational age significantly reduces incidence of post-term pregnancy.  Ultrasound measurements of crown –rump length of fetus up to about the 14th weeks and of biparietal diameter of fetal head up to about the 28th weeks give a reliable indication of duration of gestation.

Risk factors for actual postterm pregnancy include:  Primiparity.  prior postterm pregnancy( 30 %).  male gender of the fetus.  genetic factors.  Obesity.

Aetiology of prolonged pregnancy  The cause of postdate pregnancy is not clear and it may represent simple biological variation.  Prolonged pregnancy is common in association with:  an anencephalic fetus.  placental sulphatase deficiency.  extrauterine pregnancy.

Risks associated with prolonged pregnancy  Post term pregnancy per se is not a pathological condition and should not be confused with post maturity syndrome.

Fetal postmaturity syndrome  occurs in 20-30% of postterm pregnancies. It is related to the aging and infarction of placenta resulting in placental insufficiency with impaired oxygen diffusion and decreased transfer of nutrients to fetus. Fetus is typically has loss of subcutaneous fat, long fingernails, dry, peeling skin, and abndant hair.

 Not every post-term pregnancy is complicated by post-maturity syndrome.  Majority of morbidities and mortality associated with post term pregnancies arises because of post-maturity.

Fetal macrosomia  70-80% of postdates fetuses not affected by placental insufficiency continuo to grow in utero, many to point of macrosomia (birth weight greater than 4000grams) this result in abnormal labour, shoulder dystocia, birth trauma, and increased incidence of caesarean birth.  Increase perinatal mortality(2-3 times higher).

 3. Perinatal mortality (2-3 times increased risk of perinatal death).  4. Perinatal morbidity  a. Birth trauma (skull fracture, brachial plexus injuries, intracranial haemorrhage)  b. Shoulder dystocia

 c. meconium aspiration increased Meconium aspiration syndrome refers to respiratory compromise with tachypnea, cyanosis, and reduced pulmonary compliance in newborns exposed to meconium in utero and is seen in higher rates in postterm neonates  d. neonatal seizures.  e. neonatal sepsis.  h. respiratory distress syndrome.  i. Cerebral palsy.

Maternal risk:  Increased operative delivery.  Haemorrhage.  Maternal infection.  Psychological morbidities anxiety.

Diagnosis  The diagnosis of postterm pregnancy is often difficult. The accurate dating of gestation is very important.  Gestational age unreliable in calculation of gestational age in women with:  Irregular cycle.  Lactataing women.  Recent cessation of birth control pill  Thus, not only the LMP date, but the regularity and length of cycles must be taken into account when estimating gestational age.

 Ultrasound to establish accurate gestational age  Estimation range varies. For example,  crown-rump length (CRL) is ± 3-5 days,  Ultrasound performed at weeks of gestation is ±7-10 days,  at weeks is ± 2 weeks,  and after 30 weeks is ± 3 weeks.  If there is more than one week discrepancy between LMP and ultrasound finding, then the ultrasound finding should be used to determine expected date of delivery (EDD).

 Women may not know her LMP and has no early first or second trimester ultrasound we can use some points which can exclude risk of prematurity but can not calculate gestational age accurately by it:  36 weeks have elapsed since documentation of a positive human chorionic gonadotropin (+hCG) test finding.

 20 weeks of fetal heart tones have been established by a fetoscope or 13 weeks by a Doppler examination.  Antenatal records for bimanual examination of uterus at an early visit. between 8th – 14th weeks an accurate assessment of uterine size can be made.

Management:  Management option depends on:  Gestational age.  cervical examination findings.  estimated fetal weight.  past obstetric history.  Absence or presence of maternal risk.  Factors or evidence of Fetal compromise.  Maternal preference and informed consent.

Indications of delivery:  Amniotic fluid index <5 cm or maximum pool depth <2 cm  Abnormal fetal heart rate (decelerations)  Biophysical profile of 6/ 10 or less  Abnormal umbilical artery Dopplers

Management options are:  1. Elective induction of labour.  2. Expectant management with/ without antepartum testing  Simple monitoring with Non stress test (NST) cardiotocography (CTG) and liquor assessment.

Assessment of post-dates pregnancy:  Many different tests of fetal well-being are performed for assessment of post-term fetus. These include:  Cardiotocography (CTG).  Ultrasonographic testing.  Amniotic fluid index.  Biophysical profiles.  Umbilical artery Doppler waveform analyses.

Expectant management  it consists of:  daily fetal kick count  non stress test (NST) twice/ week to 42 weeks.  ultrasound to assess amniotic fluid volume twice/ week until 42 weeks.  if NST abnormal or amount of liquor is abnormal induce immediately.  induce at 42 weeks if NST is normal amniotic fluid volume is normal.

 Take history examination and investigation (NST,CTG,amniotic fluid assessment)

Management:  Elective induction of labour.  Expectant management with/ without antepartum testing  Simple monitoring with Non stress test (NST) cardiotocography (CTG) and liquor assessment.

 Management option depends on: The certainty of gestational age. cervical examination findings estimated fetal weight Absence or presence of maternal risk.  Factors or evidence of Fetal compromise.  Maternal preference and informed consent.  past obstetric history must all be considered when mapping a course of action.

 Expectant management:  Daily fetal kick count  NST Twice/ week to 42 weeks.  Ultrasound to assess amniotic fluid volume twice/ week until 42 weeks.  If NST abnormal or aount of liquor is abnormal induce immediately.  Induce at 42 weeks if NST is normal AMNIOTIC FLUID VOLUME IS NORMAL.

 Take history examination and investigation (NST,CTG,amniotic fluid assessment)

Gestaional age 40 0/ /7 weeks gestation:  A. In cases with Healthy, uncomplicated pregnancy, fetal growth and amount of liquor was normal:  Wait spontaneous labour and no need to serial investigations.  B. Presence of maternal risk factor or evidence of fetal compromise:  Delivered by Induction of labour if there is no obstetrical contraindication

41 weeks gestation:  After 41 weeks’ gestation, if the dates are certain, women should be offered elective delivery.  routine induction at 41 weeks of gestation does not increase the cesarean delivery rate and may decrease it without negatively affecting perinatal morbidity or mortality. In fact, both the woman and the neonate benefit from a policy of routine induction of labor in well-dated, low-risk pregnancies at 41 weeks' gestation.

42 weeks  delivery  there are multiple reasons not to allow a pregnancy to progress beyond 42 weeks.  Obstetricians re unable to offer complete reassurance to expectant mother who continues to awaite spontaneous onset of labour.

Intrapartum management:  Continuous electronic fetal monitoring must be employed during induction of labour.  Fetal membranes should be ruptured as early as possible to see color of amniotic fluid.casearean section is indicated for fetal distress and should not to be delayed because of decreased capacity of postterm fetus to tolerate asphyxia and increased risk of meconium aspiration.  If meconium is present neonatiologist should be present at time of delivery.  Be prepared for shoulder dystocia.

Prevention :  *Stripping or sweeping of the fetal membranes refers to digital separation of the membrane.  *Unprotected sexual intercourse.