Postterm Pregnancy Associate Professor Iolanda Blidaru MD Ph

Postterm Pregnancy Associate Professor Iolanda Blidaru, MD, Ph. D.

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 n 20 % cases of prolonged pregnancy are associated with: 1. Meconium - stained amniotic fluid 2. Oligohydramnios 4. Fetal distress Loss of subcutaneous fat 5. Cracked skin 3.

Etiologic Factors n The most frequent – an error in dating. n When truly exists, the cause usually is unknown. Risk factors n Primiparity n Prior postterm pregnancy

Etiologic Factors Rarely, it may be associated with n placental sulfatase deficiency n fetal abnormalities (anencephaly, adrenal hypoplasia, absence of pituitary gland). n male sex. n genetic predisposition.

INCIDENCE n Using the definition of 294 days, the incidence of postterm pregnancy is 3 - 12 %.

Fetal risks n The perinatal mortality > 42 weeks twice that at term > 43 weeks > 6 -fold that at term

Fetal risks Uteroplacental insufficiency→ n fetal distress, hypoxia, growth restriction n Oligohydramnios - risk for cord accidents n meconium aspiration n Macrosomia - labor abnormalities, shoulder dystocia n Sudden infant death syndrome (death within the first year of life). n

Maternal risks 1) Labor dystocia 2) Severe perineal injury related to macrosomia 3) Increased rate of cesarean delivery. 4) A source of anxiety for the pregnant woman.

DIAGNOSIS 1. Gestational age calculation n n Because actual dates of conception are rarely known, the LMP is used as the reference point. The accuracy determination of gestational age unreliable because of : 1. Irregular menses. 2. Recent cessation of birth control pills. 3. 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 women and certainly those who do not have regular menses, for gestational age determination, prior to 20 weeks.

n The available evidences are strongly in support that dating by early ultrasonography alone is a very accurate method for predicting EDD.

3. Oligohydramnios n US diagnosis v No vertical pocket > 2 cm or v Amniotic fluid index (AFI) – reduced considered an indication for delivery.

Management options depend on 1) Gestational age, 2) Absence / presence of maternal risk factors 3) Evidence of fetal compromise 4) Maternal options. v Successful management depends on effective counselling of women and their full involvement in the decision making process.

Management of prolonged pregnancy a. Inducing labour routinely at 41 -42 weeks gestation b. or Awaiting the onset of spontaneous labour, while monitoring the fetal wellbeing. n The decision is difficult.

FETAL SURVEILLANCE The condition of the fetus can change quickly → monitoring at frequent intervals. n biophysical profile n non stress test n 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 v Recommend cervical ripening and induction of labour

Management at 41 weeks gestation A. Healthy, uncomplicated pregnancy q Inform the woman of the options and risks/ benefits of labor induction versus expectant management, and offer her labor induction. q 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 Ø Daily fetal movement counts Ø Non stress test (NST) and Amniotic fluid index (AFI) twice / week to 42 weeks. Ø 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.