I M A Pregnant Lady Having Fetus Of 33 Weeks.

I m a pregnant lady having fetus of 33 weeks. During my color doppler sonograpy of 31 weeks my amniotic fluid volume was 12.36 cm. which comes to 10.16 cm. in my 33 week sonograpy. Is it safe?
Spectral waveform Flow velocity in Umbilical vein also came down to 12.37 cm/s in 33 week from 16.10 cm/s of 31 week....Is it normal or not....
Please consult me If both these things are not normal thn wht precaution or measures should I take....