is breathlessness is common in pregnancy i  am  15 weeks pregnant

hello harpreet..
not for all, some people face this problem...it depends on history of patient too whether suffering from any respiratory problems..

but my all test is ok

pft rest echo ECG etc

hamm then no need to worry , take rest and dont take any tension

Shortness of breath is normal, and another thing you may experience is that your heart rate can get much faster, especially if you're climbing stairs or something active.
A couple reasons for these things - pregnancy hormones, progesterone contributes to this.  Also, while pregnant, the volume of blood in your body increases dramatically, by as much as 50%.  

normal

yes

yes.. it happens.. it's normal.. nothing to worry..

s sometimes  it happens dont worry

yes its common at this stage.
nthing to worry

yes . thats okay.. I also feet the same almost every evening..! switching on AC for sometime helps me..

Thanks  all

my placenta is also low laying and my throat is sore

then take rest harpreet...
it is mandatory in low lying placenta..

can I do few home activities  because  without  any work I feel more  breathlessness

yeah but avoid long standing walking lifting heavy objects climbing stairs..