Chemical pregnancies take place before ultrasounds can detect a fetus, but not too early for a pregnancy test to detect levels of hCG, or human chorionic gonadotropin. This is a pregnancy hormone the embryo creates after implantation. Your doctor can confirm a chemical pregnancy by testing your blood for it.
Experiencing a miscarriage just one or two weeks after a positive pregnancy test can be devastating. I know because I had two. My loss in 2008 and also in 2011 were both chemical.
The majority of women who have had one never actually realise they’ve conceived since the only real symptom is a late period. A chemical pregnancy is sometimes revealed when an early pregnancy test shows a faint positive result but later returns a negative result in a week or two.
While a chemical pregnancy typically doesn’t cause harm to a woman’s body, it can still lead to feelings of deep sadness and grief.
Chemical Pregnancies vs Evaporation Line
An evaporation line on a pregnancy test is a line caused by the evaporation of urine on the test area causing a false positive result. An evaporation line may be caused by waiting too long and reading the result after the time limit. Although the time limit is usually the culprit for creating an evaporation line it is not always the cause and an evaporation line may develop even within the time limit.
Most chemical pregnancies are believed to occur because the fertilised egg had some sort of chromosomal abnormality that made it non-viable from the start. When the body recognises this, it will naturally terminate the pregnancy soon after the egg implants.
While the implantation itself is never actually completed, the cells of the fertilised egg will still produce enough of the pregnancy hormone hCG (human chorionic gonadotropin) to elicit a positive pregnancy test result.
In a chemical pregnancy, the gestational sac will not be large enough to be visible on an ultrasound. As such, the only way to confirm the pregnancy is through blood tests. Hence, the term chemical pregnancy refers to the biochemical means of diagnosis. By contrast, a clinical pregnancy is one in which either a fetal heartbeat is detected or there is visual evidence on an ultrasound.
Chemical pregnancies are most often identified in women who are undergoing in vitro fertilization (IVF). The heightened anticipation of a pregnancy during IVF may lead some couples to test more frequently and earlier than those conceiving naturally.
Chemical Pregnancy Causes
It is not always possible to determine the exact cause of a chemical pregnancy. However, potential causes or contributing factors may include:
- Chromosomal abnormalities: Irregularities in chromosomal arrangements may prevent the fetus from developing. Chromosomal abnormalities are the leading cause of early pregnancy loss.
- Advanced maternal age: Women aged 35 or older may find it more difficult to get and stay pregnant.
- Insufficient hormone levels: The body needs higher levels of certain hormones, such as progesterone, to support the growth of the fetus.
- Low body mass index (BMI): Women who are underweight according to their BMI are more likely to have an early miscarriage.
- Uterine abnormalities: The presence of uterine fibroids or irregularities in the uterine lining can prevent the embryo from implanting in the uterus.
Doctors don’t know what causes chemical pregnancy, but it’s thought to stem from chromosomal abnormalities that lead to improper development of the embryo. Dr. Ashley Storms, M.D., an OBGYN at Spectrum Health in Grand Rapids, Michigan, says other possible chemical pregnancy causes include infection (like chlamydia or syphilis), implantation outside of the uterus, clotting disorders, and anatomic problems. “Another theory involves problems with the endometrial lining, which prevents proper implantation and growth of the embryo,” adds Lauren Averbuch, M.D., a doctor at OBGYN Westside in New York City and a clinical instructor at Mount Sinai Hospital.
Any women can experience chemical pregnancy, but a handful of risk factors may increase your chances. These include maternal age (women over 35 have a greater chance of any type of miscarriage, says Dr. Averbuch), thyroid and blood clotting disorders, and other medical issues.
While undergoing IVF treatment doesn’t increase your risk of chemical pregnancy, it allows more possibility for diagnosis. “Women who undergo IVF have frequent blood tests and monitoring for HCG (a hormone produced after implantation). Therefore a positive HCG will be detected in IVF patients, whereas other women may miss the relatively short-lived positive hormone level,” says Dr. Averbuch.
What else you need to know
Medically, a chemical pregnancy is more like a cycle in which a pregnancy never occurred than a true miscarriage. Emotionally, it can be a very different story. It’s natural to feel upset no matter how early a pregnancy loss occurs — and it’s important to let yourself grieve if you need to. It’s also important to know that a chemical pregnancy is not your fault. Since most miscarriages are caused by chromosomal accidents, there’s nothing you can do to prevent them.
Also know that just because you had an early miscarriage doesn’t mean that you’ll have another. In fact, although it might sound unfair right now, doctors actually look at a single chemical pregnancy as a positive sign that you can get pregnant.
Signs and symptoms
The clearest indication of a chemical pregnancy is a positive pregnancy test result that is followed by a negative one. These tests can take place either at the doctor’s office or at home. A chemical pregnancy does not always cause symptoms.
If it does, they may include:
- mild spotting a week before an expected period
- abdominal cramping, which is usually mild
- vaginal bleeding that occurs close to the time of an expected period or shortly afterward
Advances in pregnancy tests mean that women can now identify pregnancies as early as the first day of embryo implantation.
However, research shows that up to 25 percent of pregnancies result in miscarriage before a woman has any pregnancy symptoms or misses a period.
The symptoms listed above can also occur with a healthy, ongoing pregnancy. If a woman believes that there are any issues with her early pregnancy, she should talk to a doctor.
A chemical pregnancy does not usually require medical intervention or treatment.
How soon can a woman get pregnant again?
Most women can attempt to get pregnant again almost immediately after an early pregnancy loss unless a doctor advises otherwise.
According to the American College of Obstetricians and Gynecologists, it is possible to ovulate and become pregnant again as soon as 2 weeks after an early pregnancy loss.
If a woman has experienced a chemical pregnancy in the past, this does not mean that she will have difficulty conceiving in the future.
In fact, a chemical pregnancy means that an embryo reached the pre – implantation phase of development. This is a positive sign that a woman could get pregnant in the future.
According to older research, women who had a chemical pregnancy in their first IVF cycle were more likely to have a successful pregnancy in a subsequent IVF cycle than women who did not become pregnant during the first cycle.