What Is a Biochemical Pregnancy?

Biochemical pregnancy is defined as the absence of recognizable pregnancy on ultrasound examination (absence of gestational sac, embryo) despite of a positive urine or blood pregnancy test. It can also be defined as very early pregnancy loss or very early miscarriage. It is characterized by transient increase in the ß-hCG hormone (<100 mIU/ml), followed by a rapid decline. This distinguishes it from clinical pregnancy, confirmed on ultrasound.  

Biochemical pregnancy often represents great disappointment for fertility patients. However, the occurrence of a biochemical pregnancy provides clear evidence that at least one embryo has reached an advanced pre-implantation stage of development (blastocyst stage) and proceeded to attempted implantation. It gives hope for a successful clinical pregnancy in the future. 

There are no scientific evidence to confirm that stress, intense exercise and heavy lifting would cause miscarriages. Those persistent fallacies bring much unnecessary guilt and suffering.

Are Biochemical Pregnancies Common?

Today, many biochemical pregnancies are detected due to the more sensitive pregnancy tests used, which can detect the presence of β-hCG even 3-4 days before the onset or absence of menstruation. It has been established that about 25% of pregnancies fail before the woman perceives any subjective sign pregnancy, that is, before menstruation is absent and before the most typical symptoms of pregnancy appear.

Possible Causes for Biochemical Pregnancy

The exact cause is unknown, but it is most often influenced by two factors: 

• Endometrial thickness and pattern: Biochemical pregnancies are related to the thickness and pattern of the endometrium, but not to a woman’s age or past pregnancy losses. Biochemical pregnancy or spontaneous abortion are not related to the levels of estradiol or luteinizing hormone (LH) on the day of the stop injection (hCG) application in MAR procedures or on the day of the LH surge in spontaneous cycles. Checking hormone levels before conception thus cannot predict which pregnancies will be healthy and successful.
• Genetics: Genetics is critical to the early development of the embryo. Recently, two different mechanisms are suggested for an early embryo loss. The first is the non- separation of chromosomes during cell division and the second is the inability of the cytoplasm and energy supply in the early embryo. This means that abnormal genetic material can appear in an egg or sperm before conception or after they unite to form an embryo in the first few days after conception.