Postterm Pregnancy Associate Professor Iolanda Blidaru, MD, PhD.
DEFINITION Prolonged pregnancy = postterm pregnancy = postdate pregnancy It is one that has lasted longer than 42 weeks or 294 days beyond the first day of the last menstrual period
Post-maturity syndrome • 20 % cases of prolonged pregnancy are associated with: • Meconium - stained amniotic fluid • Oligohydramnios • Fetal distress • Loss of subcutaneous fat • Cracked skin
Etiologic Factors • The most frequent – anerror indating. • When truly exists, the cause usually is unknown. Risk factors • Primiparity • Prior postterm pregnancy
Etiologic Factors Rarely, it may be associated with • placental sulfatase deficiency • fetalabnormalities (anencephaly, adrenal hypoplasia, absence of pituitary gland). • male sex. • genetic predisposition.
INCIDENCE • Using the definition of 294 days, the incidence of postterm pregnancy is 3 - 12 %.
Fetal risks • The perinatal mortality > 42 weekstwice that at term > 43 weeks > 6-fold that at term
Fetal risks Uteroplacental insufficiency→ • fetal distress, hypoxia, growth restriction • Oligohydramnios- risk for cord accidents • meconium aspiration • Macrosomia - labor abnormalities, shoulder dystocia • Sudden infant death syndrome(death within the first year of life).
Maternal risks • Labor dystocia • Severe perineal injuryrelated to macrosomia • Increased rate of cesarean delivery. • A source of anxiety for the pregnant woman.
DIAGNOSIS 1.Gestational age calculation • Because actual dates of conception are rarely known, theLMP is used as the reference point. • The accuracy determination of gestational age unreliablebecause of : • Irregular menses . • Recent cessation of birth control pills. • Inconsistent ovulation times.
2. Routine early pregnancy ultrasound • Reduces the number of women who require induction of labour for apparent postterm pregnancy . • It is recommended to all pregnant womenand certainly those who do not have regular menses, for gestational age determination, prior to 20 weeks.
The available evidences are strongly in support that dating byearlyultrasonographyalone is a very accurate method for predicting EDD.
3. Oligohydramnios • US diagnosis • No vertical pocket > 2 cm or • Amniotic fluid index (AFI) – reduced - considered an indication for delivery.
Management options depend on • Gestational age, • Absence/presence of maternal risk factors • Evidence of fetal compromise • Maternal options. • Successful management depends on effective counselling of women and their full involvement in the decision making process.
Management of prolonged pregnancy • Inducing labourroutinely at 41-42 weeks gestation or • Awaiting the onset of spontaneous labour, while monitoring the fetal wellbeing. • The decision is difficult.
FETAL SURVEILLANCE The condition of the fetus can change quickly→monitoringat frequent intervals. • biophysical profile • non stress test • amniotic fluid index
BIOPHYSICAL PROFILE 1. fetal heart rate acceleration 2. fetal breathing 3. fetal active movements 4. fetal tone 5. amniotic fluid volume
Management at 40-41 weeks gestation • A .Healthy, uncomplicated pregnancy + fetal growth/ amniotic fluid normal • No elective induction of labor or serial antenatal monitoring • B. Presence of maternal risk factors or evidence of fetal distress • Recommend cervical ripening andinduction of labour
Management at 41 weeks gestation • A. Healthy, uncomplicated pregnancy • Inform the woman of the options and risks/ benefits of labor induction versus expectant management, and offer her labor induction. • Assess the cervical (Bishop) Score and a ripening agent (PG) prior to induction.
Management at 41 weeks gestation • B. If mother declines induction,then provide expectant management • Daily fetal movement counts • Non stress test (NST) and Amniotic fluid index (AFI) twice/ week to 42 weeks. • If the NST or AFI is abnormal , then initiate induction immediately Induce at 42 weeks even if NST and AFI are normal.
BISHOP SCORE 1. dilatation (cm) 2. effacement (%) 3. station 4. cervical consistency (firm, medium, soft) 5. cervical position (posterior, midposition, anterior)
Management during labour and delivery • Amniotomy to diagnose thick meconium, if present → risk of meconium aspiration, continuous fetal assessment with electronic fetal monitoring. • Complications: shoulder dystocia and need for neonatal resuscitation at delivery.