This document discusses post-term pregnancy, defined as pregnancy lasting more than 42 weeks. The prevalence of post-term pregnancy is 5-10% of all pregnancies. Risk factors include errors in calculating gestational age, previous post-term pregnancies, and maternal obesity. Babies born post-term have higher risks of complications like macrosomia, birth trauma, perinatal mortality, and fetal dysmaturity syndrome. Management options include induction of labor at 41 weeks or expectant management with ongoing fetal monitoring. Both approaches have low complication rates for low-risk women when properly monitored.

1. POST TERM
PREGNANCY
Dr. SADEGH
GALAVI
IUMS

2. Introduction
 Timely onset of delivery is an important
determinant of perinatal outcome.
 Both preterm and postterm births associated
with higher rates of perinatal morbidity and
mortality

3. Definition:
 The average duration of pregnancy is 280
days(40 wks), If this period is exceeded by
14 days(2 wks), it is referred to as post
term or prolonged pregnancy.
 Postdate pregnancy implies pregnancy
lasting beyond the estimated date at 40
weeks.

4. Prevalence
 5-10% of all
 In US: 27% in the 40 th and 41 st week
5.5% at ≥42 weeks
 Affected by:
* Routine early US assessment of GA (dated by first trimester
US the
prevalence of PTP is about 2% (versus 6-12% by LMP)
* Prevalence of primigravid women
* Prevalence of women with pregnancy complications
* Local practice patterns

5. Etiology and risk factors
 Error in calculation of GA (the commonest)
 No known etiology
 Defects in fetal production of
hormones(anencephaly)
 Placental sulfatase deficiency
 Previous postterm pregnancy
* After one: two to three-fold
* After two: quadrupled
 Nulliparity

6. Etiology and risk factors
 Male fetus
 Maternal obesity
 Older/younger maternal age
 Maternal or paternal personal history of
postterm birth
 Maternal race (African-American, Latina, and
Asian are at lower risk than Caucasians)

7. Mortality and morbidity
Fetal and neonatal
 Macrosomia (≥4500g) (2.5-10% versus 0.8-1% at term)
* Prolonged labor
* Cephalopelvic disproportion
* Shoulder dystocia
* Birth trauma (brachial plexus injuries and fractures)
 Perinatal mortality
* twice the rate at term
* four-fold at 43w
 Neonatal mortality
 Placental insufficiency (hypoxia, asphyxia, meconium aspiration)

8. Mortality and morbidity
 Fetal dysmaturity (postmaturity) syndrome
* Up to 20 percent
* Placental insufficiency, chronic intrauterine malnutrition
* Oligohydramnios
* Umbilical cord compression
* Meconium passage(physiological maturation or hypoxia)
* Long thin body, long nails, SGA
* Skin is dry, meconium stained,loose, prominent creases; lanugo
hair is
absent, scalp hair increased
* Short and long-term morbidities as IUGR
 Intrauterine infection

9. Maternal risks:
Increased maternal
morbidity with large for
date or macrosomic
babies occurs because
of increased incidence
of:
• Dystocia
• Prolonged labour
• Shoulder dystocia
This results in an
increased risk of:
• pelvic floor trauma
• Instrumental deliveries
• Caesarian section (25%
incidence)
• Post partum
hemorrhage
• Endometritis

10. Management:
 Two approaches
 Both are associated with low complication rates in the low-
risk postterm gravida
 favor induction of well-dated postterm pregnancies at or
shortly after 41 0/7ths weeks
 expectant management with ongoing fetal assessment

11. Induction
 Lower perinatal mortality and morbidity
 No increase in or a reduction in cesarean
delivery
 Patient satisfaction
 cervical ripening agents even in women with
unfavorable cervices
 membrane sweeping

12. Expectant management
 Antepartum fetal demise increases with advancing GA
* 40-41 weeks: 0.86 to 1.08 per 1000
* 41-42 weeks: 1.2 to 1.27 per 1000
* 42-43 weeks: 1.3 to 1.9 per 1000
* >43 weeks: 1.58 to 6.3 per 1000
 Neither method has been proven to be superior
 NST with amniotic fluid volume assessment or by BPP
 Induction for any usual obstetrical indications
 amniotic fluid can become severely reduced within 24 to
48 hours

13. Antenatal Testing
 Risk for uteroplacental insufficiency
 Will not predict random unfortunate events
 Based on physician experience
 CST, NST, BPP, AFI
 Three protocols in 583 women with completed 42w
gestation:
1-Weekly NST with CST for nonreactive NST
2-Twice weekly NST with BPP for nonreactive NST with induction
for a
4/10 BPP
3-Twice weekly NST with BPP for nonreactive NST and a weekly
determination of the amniotic fluid volume
 Protocol 3 had the least perinatal morbidity and 1 highest morbidity