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Chemical pregnancy causes, symptoms, and moving on

Reviewed by | Last updated Sep 10, 2020 | 0 comments

Allison Schaaf - Miscarriage Hope Desk

Hi, my name is Allison Schaaf, my own fertility journey, including 5 miscarriages, inspired me to create this website to help you navigate your own fertility journey.

Here are my main takeaways I would share with you as a friend:

  • Chemical pregnancy is a loss, take the time you need to grieve and recover
  • Unfortunately, no medical intervention is going to stop a chemical pregnancy already in progress
  • This article discusses potential causes, but keep in mind that finding a cause may be difficult

I also recommend you do your own research and work with your doctor. That is why I have coordinated these articles with the nitty-gritty details and links to research so you can make an informed decision on what works best for you… read on for more! And don’t miss my Next Steps section at the bottom.

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Table of Contents

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What is chemical pregnancy?

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What are the causes of chemical pregnancy?

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Diagnosing a chemical pregnancy

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Treatments for chemical pregnancy

Chemical pregnancy is a type of very early miscarriage. It may affect up to 25% of pregnancies and 50 – 75% of all miscarriages. 1 Most women are completely unaware as they start bleeding around the same time as their typical menstrual cycles. However, if you have been anticipating pregnancy and monitoring pregnancy tests, a chemical pregnancy can be devastating. Also, it can take an emotional toll if chemical pregnancy happens multiple times. 

Couples receiving in vitro fertilization (IVF) treatments may be more aware of chemical pregnancies due to increased monitoring. The fact that they are able to achieve pregnancy at all could be a good thing because it means that the couple can conceive. 23 However additional investigations and treatments may be necessary to have successful pregnancies.

While there is no known treatment that can stop a chemical pregnancy, studies have uncovered many potential underlying causes. Many couples simply try again and become pregnant. For recurrent cases, there are many known possible causes. Once you work with your doctor to address these, you may have a fairly good chance at a successful pregnancy.

What is chemical pregnancy?

A Chemical pregnancy (also called “a chemical” or a “biochemical pregnancy”) is a pregnancy that aborts shortly after it becomes detectable by a pregnancy test, but before it becomes detectable by ultrasound. 4 The miscarriage typically occurs within 1 – 2 weeks after ovulation, around the time you expect your period. 

After the embryo implants into the endometrium, the placenta begins to release the pregnancy hormone beta-human chorionic gonadotropin (βhCG). There is just enough βhCG to result in positive blood and home pregnancy tests, but not enough to cause pregnancy symptoms. After only a few days to weeks, the pregnancy is lost, causing the βhCG levels to drop and pregnancy tests to become negative. 5 

Since ultrasound scans can only detect a pregnancy past five weeks, a chemical pregnancy is not detectable on the ultrasound. 6 

What are the causes of chemical pregnancy?  

We still don’t completely understand why chemicals happen. The following are some possible causes that studies have associated with chemical pregnancies. If you’ve had more than one chemical pregnancies, your doctor may work to diagnose the underlying causes. Addressing the underlying causes may reduce the risk of another chemical pregnancy.

Uterine and endometrial abnormalities

The endometrium is the innermost lining of the uterus. It typically develops every menstrual cycle to prepare for embryo implantation. During menstruation, you shed this lining only to begin rebuilding it again. 

Hormonal factors – Any disruption of the menstrual cycle or the preparation processes could render the endometrium incompetent for pregnancy, which may lead to a chemical pregnancy. These may include hormonal conditions such as polycystic ovarian syndrome, endometriosis, low progesterone, and luteal phase defects, etc. 78910 In cases of IVF, missing the ideal window of implantation can also cause a chemical pregnancy.

How your endometrium grows, regenerates, and decidualize during each menstrual cycle. Impairment of this process can lead to a chemical pregnancy.
How your endometrium grows and regenerates during each menstrual cycle. Decidualization is the process that the endometrium becomes receptive to the implanting embryo. Immune cells like natural killer cells are important during this process. Any impairment of this process can lead to a chemical pregnancy. 11

Impaired pregnancy progression – After the implantation process, the endometrium develops into a decidua. Decidualization is the preparation of the endometrium to accommodate pregnancy. This process requires blood vessel formation and the coordination of different types of immune cells. If these blood vessels fail to form successfully, it can lead to a chemical pregnancy. 12 Also, immunological imbalances such as autoimmune diseases, ongoing infections, vitamin D deficiency, and excess histamine can disrupt this process. 13 

Infections – Like the gut and the vagina, the endometrium has its own microbiome, which also influences implantation. 14 Bad bacteria, mycoplasma, and chlamydia infections can inflame the endometrium (endometritis) and cause chemical pregnancies. 15

Anatomic factors include uterine septum, C-section scars, uterine adhesions, fibroids, and endometrial polyps. These factors can disrupt implantation, leading to a chemical pregnancy.

DNA damage and chromosomal aberrations

DNA damage and chromosomal aberrations can abort the embryo. In a chemical pregnancy, it is difficult to evaluate chromosomal aberrations because the conceptus material is not available for testing. If the chemical pregnancy occurs due to genetic causes, then the embryo would not be viable even if they make it to the 5th gestational week.

Parental age, toxic exposures, and otherwise increased oxidative stress are risk factors for chromosomal aberrations. 16 Sperm DNA fragmentation may also be a factor contributing to a chemical pregnancy. 17

IVF and biochemical pregnancy

Couples undergoing IVF are much more likely to discover chemical pregnancies because they monitor their pregnancies more closely. Also, these couples often have multiple factors increasing their miscarriage risk. It is, therefore, easy to believe that IVF increases risk of chemical pregnancies. However, pregnancies from IVF are actually less likely to miscarry than natural pregnancies regardless of age. 18 However, IVF is typically not done in women above 42 years old. 19

Diagnosing a chemical pregnancy 

The majority of chemical pregnancies are entirely asymptomatic. Chemical pregnancy loss appears no differently than normal menstruation. The period might be a little bit early or late (a few days) and followed with more abundant bleeding or bigger clots. 20 

Signs and symptoms 

While most women will not experience any symptoms at all, some may notice the following: 2122

  • Mild spotting a week before their period is due 
  • Very mild abdominal cramping or back pain
  • Vaginal bleeding even after testing positive
  • Heavier menstrual bleeding with more blood clots

These symptoms can be confused with implantation bleeding. Also, it is possible to mistake a chemical pregnancy with a false positive pregnancy test. 

Chemical pregnancy timelines

Chemical pregnancy timeline without IVF
Chemical pregnancy timeline without IVF – This arrow shows an approximate timeline of events of when a chemical pregnancy may occur.
Chemical pregnancy timeline with IVF
Chemical pregnancy timeline with IVF – This arrow shows an approximate timeline of events when a chemical timeline might occur after the blood test shows implantation with rising β-hCG.

Testing for a chemical pregnancy

To diagnose a chemical pregnancy, your doctor looks for the combinations of 3 signs: 23

  • a low peak in β-hCG (< 100 mIU/mL)
  • a rapid fall in urinary or serum β-hCG concentration
  • a lack of substantial delay in onset of the next menstrual period to define biochemical pregnancy 

Treatments for chemical pregnancy

Is there anything you can do to prevent or treat a chemical pregnancy?

Unfortunately, no medical intervention can stop such an early pregnancy loss. 24 However, investigating the potential causes (see above) and addressing them may increase your chance of a successful pregnancy. 

If you had 2 or more chemical pregnancy losses, especially in a row, you should consult a fertility specialist. 25

If you are older than 40, you might be experiencing more difficulties in conceiving, and your doctor should help you develop a conception and pregnancy plan. 26 

When to start trying again after a chemical 

Even though you might feel disappointed with early miscarriage, it is an optimistic sign that you can become pregnant27 A healthy pregnancy is possible after you’ve had a chemical. Once you are ready, you can start trying in the next cycle.

Next Steps to Consider

  • If you have had 2 or more chemical pregnancy losses, seek help to start investigating potential causes
  • And if you are struggling emotionally, seek the help of a qualified therapist or other health professional to help you deal with your loss(es)

References[+]

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