A Cryptic Pregnancy is a pregnancy where there is NO detectable hCG in the mother's system, due to a hormonal imbalance in the mother. The fetus may go undetected by mother and doctors, until delivery, but MANY of these women are e VERY aware that they ARE pregant. The women who do know that they are pregnant, cannot get medical confirmation of the pregnancy due to negative, hCG tests including home pregnancy tests and hCG blood tests. Characteristics of a cryptic pregnancy are; negative urine and blood pregnancy test, continued "odd periods", typical pregnancy symptoms (although they are often milder than in a normal pregnancy, and come and go) and negative ultrasounds.  Cryptic pregnancies are typically carried between 3 and 7 years due to slow growth of the fetus, caused by low hCG, due to the hormonal imbalance.