Early Home Pregnancy Test - When Positive?

An early pregnancy test checks for the presence of the pregnancy hormone hCG human chorionic gonadotropin in the urine.
hCg is detectable in the blood only after implantation. Implantation, the attachement of the fertilized egg to the uterus, happens on average 7-9 days after ovulation with a range of 6-12 days. You need to find enough hCG in the urine to get a positive pregnancy test, and with most current pregnancy test kits (sensitivity 25 milli-international units per milliliter) the pregnancy hormone hCG can be detected in the urine as early as 3-4 days after implantation (9-15 days after ovulation), though oftentimes it can take longer because the urine may be diluted or there is not enough hCG yet in the urine, or implantation happens later than extected. Our pregnancy calendar will help you calculate the due date and other important dates, and our ovulation calendar will calculate your fertile days.
hCG levels are also higher in women carrying a female fetus when compared to women carrying a male fetus, so it is possible that the pregnancy test becomes positive later in women carrying a male fetus (Read HERE more).

Why does it take sometimes longer for the pregnancy test to become positive?
What makes the pregnancy test become positive?
Here are the expected positive positive home pregnancy tests in women who are pregnant based on a scientific study:

Expected Period (EP)

• About one in two HPTs are expected to be positive 2-3 days before a missed period
• Three in four HPTs are expected to be positive on the day you miss your period
• A negative pregnancy test on the day of a missed period is normal in about one in four pregnancies, and within the next 4-5 days most HPTs usually have become positive.
• A negative HPT result 10+ days after the missed period makes a pregnancy unlikely.

From: Wilcox in JAMA 2001; 286:1759