The number of spontaneous movements tends to increase until the 32nd week of pregnancy. After the frequency plateaus ( DOES NOT DECRESE). 

 Factors which may lead to reduced perception of fetal movement or  are-
1. If mother is busy,
2. Anterior placenta( this is applicable prior to 28 weeks gestation),
3.  Fetal position( E.G fetal spine anterior) .

Reduced fetal movements can be seen with-
1. Cigarette smoking( Increased CO2 in maternal blood),
2. Some congenital malformations in the fetus.

FETAL PRESENTATION has no effect on fetal movement perception.