Post-term pregnancy (syn: postmaturity)

Question 1

What is post maturity?

Answer 1

A pregnancy continuing beyond 2 weeks of the EDD (> 294 days) is called a post-term pregnancy
 Prolonged or post-date pregnancy- Is one that persists beyond EDD, 40 weeks (280 days) from onset
of LNMP.

Question 2

Consequence of post-term pregnancy

Answer 2

 Placental function starts to deteriote after 42 weeks – due to deposition of calcium on walls of blood vessels and
deposition of protein on the surface of the placenta and so placental inefficiency ensues
 Its associated with increased risks to both fetus and mother; stillbirth and perinatal death, prolonged labour
and an increased risk of Caesarean section
 Increased risk to fetus and neonate is due to development of fetal postmaturity (dysmaturity) syndrome,
resulting from a growth restriction of fetus who remains in utero beyond term, due to aging and infarction of
the placenta placental insufficiency
 70-80% of postdate fetuses not affected by placental insufficiency continue to grow in utero, many to the point
of macrosomia (BWT > 4000 g), often predisposing to abnormal labor, shoulder dystocia, birth trauma, and an
increased incidence of cesarean delivery

Question 3

Incidence of post-term pregnacy

Answer 3

Approximately range from 6-12% of all pregnancies are postdates pregnancy based on LMP.
 Perinatal mortality is doubled by 42 weeks and quadripled by 44 weeks gestation
 Incidence has been reduced significantly in the past 10 years because of induction before 42 weeks reducing fetal
morbidity secondary to prolonged gestation

Question 4

Etiology of post-term pregnancy

Answer 4

Most postdates pregnancies are idiopathic
 But certain factors are related with post-maturity.
a) Wrong dates- inaccurate LMP (most common), can be due to; Irregular menses, recent discontinuation of
contraception, poor memory of LMP, pregnancy occurring during lactational amenorrhea
b) c) Biological variability (Hereditary) may be seen in certain families
Maternal factors: i) Primiparity, ii) previous prolonged pregn, iii) sedentary habit, iv) elderly multiparae, v)
Maternal obesity
d) Fetal factors: i) Congenital anomalies: Anencephaly → abnormal fetal HPA axis and adrenal hypoplasia →
diminished fetal cortisol response, ii) Fetal adrenal hypoplasia
e) f) Placental factors: placental sulphatase deficiency → low estrogen
Abdominal pregnancy / extrauterine pregnancy

Question 5

Diagnosis of post-term pregnancy

Answer 5

Hard to diagnose postmaturity if pt is first seen beyond the expected date
 1st trimester obstetric scan estimation of CRL may help to date the pregnancy if LMP is incorrect
 Diagnose at least fetal maturity, if not postmaturity using the following clinical guides:
 LMP- fairly reliable diagnostic aid in GA calculation if pt has regular cycles and sure of her dates
 Clinical finding in postterm pregnancies
1. Stationary or even reducing body weight
2. Gradual diminishing abdominal girth: due to diminishing liquor
3. History of false pain which subsides spontaneously
4. Obstetric palpation: liquor amnii diminishes, uterus feels “full of fetus” and easily palpated fetal parts,
↓HOF for GA, and hardness of the skull bones
5. Internal examination: ripe cervix though unripe cervix does not exclude maturity. feeling of hard skull
bones either via cervix or fornix
6. Investigations: Aims to confirm the fetal maturity and detect placental insufficiency
a) Sonography: early (first trimester) ultrasound is more accurate in GA estimation than LMP.
b) Amniocentesis:
c) Straight X-ray abdomen:
 Thickness and density of skull bone shadow,
 Appearance and density of ossification centers in upper end of the tibia (38–40 weeks) and lower
end of the femur (36–37 weeks).
d) Fetal well being assesssment twice weekly by nonstress test, biophysical profile and U/S estimation
of amniotic fluid volume.
 If Amniotic fluid pocket is < 2 cm and AFI < 5 cm indicates induction of labor or delivery

Question 6

clinical features of post term baby

Answer 6

 Fetus with postmaturity syndrome typically have;
 Long fingernails
 Abundant hair.
 Baby looks thin and old with wrinkled, dry, peeling skin due to loss of
subcutaneous fat.
 Absence of vernix caseosa.
 Body and the cord are stained with greenish yellow color.
 Head is hard without much evidence of moulding.
 Weight often > 3 kg and length is about 54 cm, and or even be an IUGR baby.
 Scanty Liquor amnii which may be meconium stained.
 Placenta: evidence of ageing manifested by excessive infarction & calcification.
 Cord: diminished quantity of Wharton’s jelly.

Question 7

Complications of post-term pregnancy:

Answer 7

Complications of post-term pregnancy: main clinical significance of post-term preg is dysmaturity/ macrosomia
 FETAL: Diminished placental function,
 Oligohydramnios
 Meconium stained liquor lead to fetal hypoxia and fetal distress.
 Fetal hypoxia (low Apgar scores)
 Respiratory failure and acidosis
 Meconium aspiration- leading to chemical pneumonitis, RDS, atelectasis and pulmonary hypertension
 Risks of cord compression due to Oligohydramnios
 Shoulder dystocia due to macrosomia- leading to Brachial plexus injury;
i. Erb-Duchenne palsy (C5, C6) ii. Klumpke paralysis: injury to C8, T1
 Non-moulding of head due to hardening of skull bones
 Hypoglycemia and polycythemia
 Perinatal morbidity and mortality
 Maternal complication
 Psychological stress
 Labor dysfunction
 Induced labour
 Increased incidence of birth trauma due to big size baby (3rd- and 4th-degree perineal lacerations)
 Increased incidence of operative and instrumental delivery.
NB: Postmaturity per se does not put the mother at risk

Question 8

Management of post maturity

Answer 8

 Be certain about the maturity of the fetus
 Fetal surveillance and induction of labour may reduce the risk of adverse outcome.
 Increase fetal surveillance (twice weekly) when pregnancy continues beyond 41 weeks
 Aims to identify fetuses with postmaturity syndrome that are at risk of intrauterine hypoxia & fetal demise.
 Induction of labor may be considered at or beyond 41 weeks to reduce risk of stillbirth.
 U/S scan temporary give reassurance if amniotic fluid and fetal growth are normal.
 Similarly, a CTG should be performed at and after 42 weeks.
 With reassuring biophysical profile of fetal wellbeing, timing of delivery can be pt individualized.
 Do immediate induction of labour or delivery if:
 Reduced amniotic fluid on scan; oligohydramnios (AFI < 5)
 Reduced fetal growth
 Reduced fetal movements;
 CTG is not reassuring; if spontaneous fetal heart rate decelerations are found on the NST.
 Mother is hypertensive or suffers a significant medical condition
 Influenced by profound patient’s emotional concerns
 Firmly established GA at 41 weeks, well fixed fetal head in the pelvis, and favorable cervix
 For uncomplicated post-term pregnancy- parameters of fetal well-being are reassuring, conservative mgt is an
option. Wait for spontaneous onset of labour
 Do a twice-weekly NST and modified biophysical profile, ultrasonic measurement AFI, fetal kick counts
• AFI is the sum of vertical dimensions (in cm) of amniotic fluid pockets in each of 4 quadrants of
gestational sac.
 Routine induction: induce labour if expectant attitude is extended for 7–10 days past the EDD.
• With favorable (ripe) cervix induce labour by membranes stripping or by low ROM or using of Foley
catheter. If liquor is clear, add oxytocin infusion to be more effective
• For unripe cervix, it’s ripened with PGE2 gel/tab, followed by low ROM. Add oxytocin infusion if
required. Cervical length (TVS) < 25 mm is a predictor of successful induction of labor.
 For those associated with complicating factors e.g., elderly primigravidae, preeclampsia, Rh-incompatibility,
fetal compromise or Oligohydramnios - Elective cesarean section is advisable
 These may produce placental insufficiency- Ideally pregnancy should not be allowed beyond EDD.
 Care during labor: spontaneous or induced, labor is expected to be prolonged because of a big baby and poor
moulding of the head.
 Give analgesia for pain relief.
 For macrosomic babies anticipate shoulder dystocia
 Careful fetal monitoring is mandatory.
 If fetal distress appears, promptly delivery either by cesarean section or by forceps/ventouse.
 If meconium is present, anticipate neonatal asphyxia, & a neonatal resuscitative team should be
present at delivery