This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormal labor, Subject name: Anatomy
Traction force required for forceps delivery in primigravida is : 
Select and explain. 
A. 15 kgs, B. 18-20 kgs, C. 13 kgs, D. 25 kgs
B: 18-20 kgs
Answer: B: 18-20 kgs 
Explanation: Traction force required by forceps is: Primigravida -18-20 kgs Multigravida-13 kgs Vacuum - initial pressure is 0.2 kg/cm2 induced over 2 minutes. The pressure is gradually increased at the rate of 0.1 kg/cm2 to a maximum of 0.8 kg/cm2. Ref: Datta Obs 9e pg 533.