It is generally recommended to take a pregnancy test from the first day of a missed period for reliable results. For the most accurate result, waiting about one week after the missed period is ideal, as this allows the pregnancy hormone hCG to build up to detectable levels. Some very sensitive pregnancy tests can detect pregnancy a few days before the missed period, but testing too early may result in a false negative. If the menstrual cycle is irregular or uncertain, testing at least 21 days after unprotected sex is advised. Blood tests can provide more sensitive and accurate results if needed. In summary:

• Test on the first day of the missed period for most home tests.
• For highest accuracy, wait about a week after the missed period.
• Some tests can detect pregnancy earlier but with less reliability.
• If uncertain about the cycle, test 21 days after unprotected intercourse.

This guidance helps minimize false negatives and increases the reliability of pregnancy test results.