If i missed my period by one day.can i check using pregnancy test?

Sure - 90% sensitive: Modern home pregnancy tests become positive in 90% of early pregnancies within a day of late period. A week later their sensitivity in detecting early pregnancy is up to 99-100%, so if the first test is negative and your period does not come one week later check again. Take Folic Acid 1-5 mg daily and best of luck!

Yes: A pregnancy test is reliable this soon.