The earliest form of miscarriage. The word "chemical" refers to the pregnancy being too early to confirm except through biochemical means. Home pregnancy tests and hCG blood tests will be positive, but the baby and gestational sac will not develop enough to be visible on an ultrasound. (When the ultrasound can confirm the pregnancy, it is a "clinical" pregnancy.)
The term "chemical" pregnancy can be confusing. In a chemical pregnancy, the sperm and egg do meet but the fertilized egg does not implant properly in the uterus, resulting in an early miscarriage.
Chemical pregnancies are not uncommon. Doctors sometimes advise women to wait to use a pregnancy test until their menstrual periods are actually late in order to avoid detecting and grieving chemical pregnancies because an early pregnancy test often will come up positive but then the woman's menstrual period arrives on time or a few days late. The bleeding may be slightly heavier and more crampy than a normal period.