Pregnancy tests measure the HCG hormone level of your body. HCG increases continuously after implantation and reaches measureable values after 7-12 days. It is advisable to do a urine pregnancy test a week after your missed period or 1-2 weeks after sex.

Sensitivity of different brands for HCG is different. It is described in mIU/mL {milli international units per milli Litre}. It is mentioned on the pack. It ranges from 10 to 40. The lower the value, the more sensitive the test is. A more sensitive test can give results earlier than a less sensitive pack.

If after a week of missed period, you get a negative result, you may have ovulated later than you thought. Wait for three days and if you still don’t get your period, test again.

Blood tests give results earlier than urine tests but are not indicated in routine use because they are cumbersome and present a risk of infection. They are a part of EPAU (early pregnancy assessment unit) and are indicated only when pathology like vaginal bleeding or history of ectopic pregnancy is present.

Read more: Early Signs of Pregnancy