This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnosis in obstetrics, Subject name: Gynaecology & Obstetrics
A pregnant woman at 35 weeks pregnancy complains of decreased fetal movement. Next step in management is : 
Select and explain. 
A. Observation, B. Do NST, C. Do CST, D. Do BPS
B: Do NST
Answer: B: Do NST 
Explanation: Reduction and cessation of movements may precede fetal death by a day or two.Failure to perceive 10 movements in a 12 hour period should prompt fuher biophysical assessment.NST is currently the most common method to assess fetal well being.It has been incorporated into biophysical profile.The test is based on the hypothesis that the hea rate of a fetus which is not acidotic due to hypoxia will accelerate in response to fetal movement. TEXTBOOK OF OBSTETRICS, SHEILA BALAKRISHNAN ,Pg no:509,2nd edition