A pregnant woman at 35 weeks pregnancy complains of decreased fetal movement. Next step in management is :

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