Pregnant with a Negative Pregnancy Test?

    The timing of a positive pregnancy test depends on when there is enough of the pregnancy hormone hCG in your urine and that depends on implantation.

    When does implantation of the fertilized egg happen?

    Implantation happens when the fertilized egg (blastocyst) attaches to the uterine wall and starts producing the pregnancy hormone hCG. The egg becomes fertilized with a sperm within 12 hours after ovulation, usually in the outer portion of the fallopian tube. It then travels down the fallopian tube, increasing its size along the way. In the fallopian tube it becomes the zygote and doubles to two cells, four cells, then eight cells and becomes the "morula." As the morula enters the uterine cavity it's called a "blastocyst." 
    In one important study implantation happened in 84% of pregnancies between days 8 and 10 after ovulation. There was an increase of miscarriages when implantation happened later. The rate of early pregnancy loss was 13% when implantation happened by day 9, it rose to 26% with implantation on day 10 after ovulation, it rose to 52% if implantation was on day 11 after ovulation, and to 82% if implantation was later than 11 days after ovulation.

    When is the pregnancy test positive? 

    If you are pregnant then a urine pregnancy test is not expected to be positive until at the very earliest 3-4 days after implantation, which is about 10 dpo days after ovulation/fertilization (4 days before the next period), and about 51% of pregnant women have a positive pregnancy test 2 days before the expected next period. What are your chances of still being pregnant when you are trying to conceive and have a negative pregnancy test? What are your chances getting a positive HPT if you are pregnant? Below is a table showing your chances of still being pregnant or not being pregnant with a negative pregnancy test on different days of your menstrual cycle.

    Days Post Ovulation (DPO)
    Day of
    Expected Period (EP)
    Negative HPT and Your Chance of Still Being Pregnant 
    Negative HPT and Your Chance of NOT Being Pregnant
    %  of Pregnant Women with a positive Pregnancy test
    12 DPO
    EP -3
    12.3%
    87.8%
    51%
    13 DPO
    EP -2
    9.5%
    90.5%
    62%
    14 DPO
    EP -1
    8.0%
    92.0%
    68%
    15 DPO
    Expected period
    6.5%
    93.5%
    74%
    16 DPO
    EP +1
    5.3%
    94.8%
    79%
    17 DPO
    EP +2
    3.8%
    96.3%
    85%
    18 DPO
    EP +3
    2.5%
    97.5%
    90%
    23 DPO
    EP +7
    1%
    99.0%
    96%
    Date are based on the assumption that each menstrual cycle there is an about 25% chance of getting pregnant as well as a scientific study published by Wilcox in JAMA in 2001