My wife is 30 days late with her period and has taken a test which came out negative,she however has a slight pain in her stomach.coukd she be pregnan?

Delayed menses: If your wife has a history of regular cycles, being "30 days late" at approximately your age (?) with a pain in her lower abdomen (stomach?) may indicate a pregnancy in an abnormal location, which would not be detected by a normal pregnancy test. Get a serum HCG test which is very accurate even with displaced locations of pregnancy.