This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Gynaecology & Obstetrics
Post term labour is seen in: 
Select and explain. 
A. Hydramnios, B. PID, C. Anencephaly, D. Multiple pregnancy
C: Anencephaly
Answer: C: Anencephaly 
Explanation: Causes of Post-term pregnancy:

Wrong dates: due to inaccurate LMP (most common).
Biologic variability (Hereditary) may be seen in the family.
Maternal factors: Primipara/elderly multipara/H/o previous prolonged pregnancy, sedentary habit.
Fetal factors: Congenital anomalies: Anencephaly – (Abnormal fetal HPA axis), adrenal hypoplasia (Diminished fetal cortisol response).
Placental factors: Sulphatase deficiency (Low oestrogen).