How common is it to get a false negative on a pregnancy test?

Depends: Almost all comercial preg tests report efficacy close to 99%. Trick is however, that depends on when they are done. There is a higher false negative rate if performed before the time os the missed cycle. Most-if not all- pregnancy tests should be positive by one week after a missed cycle. Always check the boxes. They state their "sensivitiy" level.

Agree with Dr. C: A negative result on a test done too soon is not reliable. If you miss your period by 4-5 days, do a home pregnancy test. If the result is negative repeat the test 4-5 days later unless you get a period by then. Use first morning urine and follow the instructions for the test carefully. If you do not wish to be pregnant, use contraception all the time, every time.