How accurate is it to do a blood pregnancy test 10 days before your period if 35 cycle?

It is not recommended to take a blood pregnancy test 10 days before your period if you have a 35-day cycle, as the results may not be accurate.

The accuracy of a blood pregnancy test depends on several factors, including the time of testing and the sensitivity of the test. Most blood pregnancy tests are designed to detect the presence of human chorionic gonadotropin (hCG), a hormone produced by the developing placenta during pregnancy. hCG levels typically start to rise a few days after implantation of the fertilized egg and double every 1.5 to 2 days in early pregnancy.

In general, blood pregnancy tests are more sensitive than urine pregnancy tests and can detect hCG levels as low as 5-10 mIU/mL. However, if the hCG levels are still low at the time of testing, the results may be falsely negative.

For a 35-day cycle, ovulation typically occurs around day 21. Implantation can happen 6-10 days after ovulation, which would be around day 27-31 of your cycle. By day 35, hCG levels may still be low and may not be detectable by a blood pregnancy test.

It is generally recommended to wait until at least the first day of your missed period or day 28 of your cycle (whichever comes first) before taking a blood pregnancy test for the most accurate results. If you are concerned about pregnancy and want to get tested early, you should talk to your doctor or healthcare provider about your specific situation and the best time to take a pregnancy test.