Post-term pregnancy( post-maturity, prolonged pregnancy )

Name : Vihari Vichakshana RajaguruGroup No 324th year 2nd semester ( 2016 )

Definition- pregnancy which has extended beyond 42

weeks of gestation period ( > 294 days)- Incidence of post-term pregnancy is 4-14%

( generally 10% )

Etiology- inaccurate dating (ex: patient doesn’t remember the last

day of menstruation )- biological variability ( hormonal factors and genetic

predisposition ) - maternal factors : previous prolonged pregnancy, elderly

multiparae, primiparity, irregular menstrual cycle, obesity

- fetal factors : congenital anomalies (anencephaly)- extra uterine pregnancy- placental factors : sulphate deficiency

Path physiology• Abnormal fetal hypothalamic-pituitary-adrenal

and adrenal hypoplasia as in anencephaly deficiency of dehydro-epiandrosterone reduced fetal cortisol response.

• Placental Salphatase deficiency- this enzyme

play a critical role in synthesis of placental estrogens which are necessary for the expression of oxytocin & PG receptors in myometrial cells

Physiological changes associated with post-term pregnancy

• Placental changes : ageing of the placenta , calcification, infractions

• Amniotic fluid changes : oligohydramnios, cloudy, presence of meconium

• Fetal changes : macrosomia, intrauterine malnutrition

Fetal & maternal risks• Fetal risks :

- fetoplacental insufficiency- meconium aspiration- oligohydramnios

• Maternal risks :- large for gestational age- increased incidence of vacuum assisted, forceps assisted or cesarean delivery - psychological stress- probable labour induction

Diagnosis• Menstrual history : mistaken maturity,

pregnancy occurring during lactational amenorrheoea, withdrawal of contraceptive pill

• Suggested clinical findings:- weight record- girth of abdomen- history of false pain- obstetric palpation- internal examination

Invasive

• Invasive methods- Amniocentesis : orange

colour cells, presence of phophatidyl glycerol, creatinine concentration, spectrophotometric study

• Non-invasive methods- Radiography : ossification centres upper and

lower ends of tibia, femur, thickness and density of skull bone shadow

- Non-stress criteria : records fetus movement, heartbeat, and contractions. Reactive/ non reactive

- Sonography : increased HC, AC, biparietal diameter

- Biophysical test ( amniotic fluid index )- Doppler flow study : amount of blood flowing

in and out of the placenta.

oligohydramnios ultrasound

Complications

Maternal – Increased morbidity due to increased instrumental & operative delivery

Fetal - Intra-partum fetal distress

- Fetal hypoxia & acidosis - Meconium aspiration syndrome - Fetal trauma due to macrosomia - Neonatal complications (hypoglycemia , etc)

- Increased Perinatal morbidity & mortality - Shoulder dystocia

Patient with Prolonged Pregnancy (>40wks) who need to be delivered :

* Women with medical or obstetrical complications of pregnancy * Favorable Cervix Bishop Score > 8 * Women with oligo-hydromnios * Estimated fetal weight > 4.5kg * Suspected fetal compromise * Fetal congenital anomaly * Hyper-mature Placenta

Expectant management of prolonged pregnancy is justified only when:

• - GA <41 wks with un-ripe cervix, normal AFI , normal size baby , normal BPP and reactive NST• There is universal agreement that once pregnancy

reaches 42wks delivery mandatory – Induction/ CS -If there is signs of fetal distress ,wt. is > 4.5kg or obstetrical complicated pregnancy - CS

Characteristics of post-term baby• decreased amount of soft-

tissue mass, particularly subcutaneous fat. The skin may hang loosely on the extremities and is often dry and peeling. The fingernails and toenails are long. The nails and umbilical cord may be stained with meconium

References

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3991404/http://ije.oxfordjournals.org/content/early/2012/04/11/ije.dys043.full

2. http://www.aafp.org/afp/2005/0515/p1935.html

3. http://www.mountsinai.on.ca/care/placenta-clinic/complications/placentalinsufficiency

4. http://www.nlm.nih.gov/medlineplus/ency/article/001596.htm

5. http://www.mayoclinic.org/tests-procedures/labor-induction/basics/risks/prc-20019032