Biochemical Pregnancy
Due to the advent of sensitive pregnancy tests a biochemical pregnancy is a recent phenomenon:
It is a pregnancy that is detected by biochemical means only (pregnancy test), and the patient either does not miss her period, or starts only a couple of days late.
These are pregnancies in which the HCG test is positive but low; and no pregnancy is ever documented on ultrasound. Biochemical pregnancies are often seen after IVF.
After IVF and embryo transfer we ,of course, know that fertililization has occurred, embryos have developed and have been place in the uterus. The pregnancy test is taken at the earliest possible moment.
In normal circumstances most women not expecting a pregnancy would wait a few days if her period is late
While they are not clinical pregnancies (pregnancies confirmed by fetal heart on ultrasound) it suggests implantation had occurred although fleeting; they are of useful prognostic information, because they may mean that your chances of getting pregnant in a future cycle are good.
