This is a medical term for a very early miscarriage. This type of loss usually occurs before or right around when a woman would expect her period.
You may feel like you are hearing more about chemical pregnancies these days, that is most likely because of very early pregnancy testing at home. These early pregnancy tests can give an accurate positive result before you expect your period. Then the pregnancy fails. Without these tests the woman would not have known she was even pregnant.
Chemical pregnancies are not the result of anything that you have done. They can be caused by chromosomal disorders, hormonal issues, luteal phase defect (LPD), problems with the lining of the uterus, some infections or even structural abnormalities within the uterus, including fibroids.
While very unlikely, reoccurring chemical pregnancies need to be treated by your doctor or midwife. There may be some medicinal therapies that can be beneficial, depending on what your practitioner feels is the cause of your problems. Some include hormone therapies, antibiotics or even baby aspirin.