The best time to take a pregnancy test is in the morning, using your first urine of the day. Most at-home urine pregnancy testing kits become more accurate usually after the first day, and preferably after the first week after your period is due. However, the later one tests after unprotected sex, the better!

The first urine of the day, after you wake-up, is more likely to contain the highest concentration of pregnancy hormones. All urine pregnancy tests rely on detecting levels of a particular hormone in your body called HCG (Human Chorionic Gonadotropin). After a fertilised egg attaches itself successfully in the walls of your uterus (this is called implantation), your body suddenly kick-starts the production of HCG in large quantities. HCG is “the” pregnancy hormone and it plays a vital role in promoting several changes, hormonal and developmental, which are vital for a pregnancy to be preserved. Thus it is an indicator of pregnancy . Now, HCG can easily be detected in the blood a lot earlier, but as it gets filtered out into the urine stream, especially in early weeks of pregnancy, it may be too low to detect. That is why most urine pregnancy tests advise its buyers to wait for at least a day after the period is missed, to test. Testing early can lead to a false negative!

Additionally, if you cannot wait for a month and need to know sooner, or if you do not have the privacy to purchase and take a urine pregnancy test, you can take a blood test to determine if you are pregnant. This is called a Quantitative blood test. It can detect pregnancy as early as 6-8 days after ovulation (so, shortly after unprotected sex). In addition to measuring the presence of HCG, it also measures the amount of HCG, which can give a sense of how far along you are in your pregnancy. It is generally considered to be a lot more accurate than a urine test.


Sources:

1-https://www.womenshealth.gov/pregnancy/you-get-pregnant/knowing-if-you-are-pregnant

2-https://www.womenshealth.gov/pregnancy/you-get-pregnant/knowing-if-you-are-pregnant