What is the longest after a missed period that anyone has had a false negative?
Nobody ever has a false negative after a truly missed period. When it happens, it is because the cycle has become disrupted, ovulation having taken place later than expected and the true due date of the period being much later. Home Pregnancy tests are scientific and proven to detect pregnancy from 14 days after ovulation. This is the day the period is due. Some women will get a pos result earlier, and if so, it will always be correct, but a neg result done early is not reliable, and therefore a false negative. If done on or after the due date of the period, you will not get a false neg.