A biochemical pregnancy can happen very early in a pregnancy
A biochemical pregnancy has many names in our field of medicine. You may have heard of a “chemical pregnancy,” “spontaneous abortion,” “false positive pregnancy test”, or “pre-clinical embryo loss.” But regardless of the name, all of these terms pretty much reference the same thing: a very early pregnancy loss characterized by a positive pregnancy test that is not maintained.
With a biochemical pregnancy, the embryo never reaches the stage where a gestational sac is seen on an ultrasound. Your blood test says you are pregnant, but we can’t see the pregnancy during a scan. The word “chemical” comes into play because the pregnancy is diagnosed only by chemical means. That is, through the blood test that measures the pregnancy hormone human chorionic gonadotropin, or hCG.
What happens during a biochemical pregnancy?
With a biochemical pregnancy, you are indeed pregnant. It is just that it doesn’t last. The fertilized egg implants into the uterine wall and the embryo produces just enough hCG to be detected on a pregnancy test. However, very soon after implantation, the embryo stops developing and your hCG levels start dropping. Soon, the uterus sheds its lining, leading to a miscarriage that is often mistaken for a delayed or heavy period.
Why does the pregnancy stop developing? There can be many reasons, but the most common is a genetic issue that likely occurs at the moment the egg and sperm unite and share their DNA. Sometimes, through no fault of your own, when the embryo forms it may contain too many or too few chromosomes. Other times, translocations occur in which parts of chromosomes break off and change places with another chromosome. In these situations, the embryo may stop developing.
Problems with the uterine lining or the receptivity of the lining can also lead to a biochemical pregnancy. Additionally, immunological or endocrine issues from the mother can be the problem, although these are less common.
Are there more women having biochemical pregnancies now?
While it might seem that biochemical pregnancies are on the rise, the reality is that in the past few decades our testing has become so sensitive that we can now detect a very early pregnancy. The invention of highly sensitive pregnancy tests has now made early diagnosis of pregnancy, at around two weeks or less, widely possible. Additionally, for those going through IVF, we know when the embryo transfer occurs and we test for pregnancy about two weeks later.
In naturally occurring pregnancies, biochemical pregnancies are thought to be fairly common. Researchers believe that as many as half of all pregnancies end in early miscarriages. An accurate number is hard to determine because most women who experience a biochemical pregnancy never even realize they are pregnant unless they are trying to conceive and testing regularly and early. Many biochemical pregnancies are discovered today that would otherwise have gone undetected due to the ultra sensitive pregnancy tests on the market, which make it easier to get a positive result 3 or 4 days before a woman’s period is due.
What to do if you have more than one biochemical pregnancy?
As mentioned in the previous section, biochemical pregnancies are fairly common. However, experiencing several biochemical pregnancies is reason to be concerned. A discussion with your Fertility Answers reproductive endocrinologist can pinpoint the possible causes and rule out other conditions. Pre-pregnancy genetic testing can uncover possible genetic issues from one or both parents. And further investigation on your uterus and endometrial lining may uncover receptivity issues.
