What is a chemical pregnancy, and why does it happen?

a woman with her head down

When a miscarriage happens within the first five weeks of pregnancy, it is known as a chemical pregnancy. It usually happens because the embryo stops growing. Anyone can experience a chemical pregnancy as there is usually no way to avoid it. However, there are a few risk factors such as age, hormone levels, chromosomal abnormalities and other infections that can increase the chances of a chemical pregnancy.

Generally, a chemical pregnancy gets resolved on its own. However, you may consult your practitioner to understand the possible cause behind it. Read on to learn more about chemical pregnancy, its causes and its treatment.

What is a chemical pregnancy?

A chemical pregnancy is an early miscarriage that happens shortly after the embryo implants in the uterus, typically within the first five weeks of pregnancy. “It is often detected by a pregnancy test but may be confused with a late menstrual period,” says obstetrician and gynaecologist Dr Kavitha Kovi.

Many women may not even realise they are pregnant because the loss occurs so early. The Journal of Clinical Medicine Research states that 50-60 per cent of first-time pregnancies end in a miscarriage, and 25 per cent of these happen when the woman doesn’t even know that she is pregnant.

Symptoms of chemical pregnancy

There are no symptoms as such for a chemical pregnancy. While some women don’t even get to know that they are pregnant, others have a few symptoms that can indicate a chemical pregnancy. “Symptoms include a positive pregnancy test followed by a negative one, light bleeding or spotting, mild abdominal cramping, and the absence of other early pregnancy signs like nausea,” says Dr Kovi. These symptoms are often similar to those of a regular period, making them easy to overlook.

Why does chemical pregnancy happen? Know its causes

1 Abnormalities in chromosomes

An embryo with the wrong number of chromosomes usually leads to an early miscarriage. This is the way the body naturally prevents embryos from developing that are not viable. A study published in the Maedica states that chromosomal abnormalities are responsible for at least 50 per cent of first-trimester miscarriages.

2. Hormonal imbalances

Progesterone is one of the hormones necessary to maintain pregnancy and insufficient hormone levels can cause a miscarriage at such an early stage, reports this study, published in Revista de Chime. Hormonal treatments may be helpful in subsequent pregnancies sometimes.

Recurrent chemical pregnancies can be emotionally draining. Seeking the help of a support group or therapy helps. Image courtesy: Freepik

3. Uterine abnormalities

There may be structural problems such as fibroids or scar tissue which can interfere with embryo implantation and growth. These conditions can often be diagnosed using imaging tests and treated with medicine or surgery. It is seen that women who experience pregnancy loss often have a 3.2 to 6.9% chance of a uterine anomaly, states this study, published in Seminars in Reproductive Medicine.

4. Infections

Some infections hinder the proper development of an embryo while some don’t affect it at all. Regular medical check-ups help avoid late diagnoses and treatment of infections. According to this study, published in Human Reproductive Update, 15 per cent of early miscarriages are due to infections that may be preventable. Another study, in the journal Diagnostics, states that human papillomavirus (HPV) can infect the placenta, resulting in an infection in the first trimester of pregnancy.

5. Immune system issues

When the immune response becomes overactive, it may attack the embryo hence causing chemical pregnancy; specialised therapies and medications exist that would help control this disorder.

The connection between in-vitro fertilization (IVF) and chemical pregnancy

In-vitro fertilization (IVF) is a process where an egg is fertilized by sperm outside the body in a lab. The resulting embryo is then placed into the uterus in hopes of establishing a pregnancy. IVF is often used by couples facing infertility issues and has helped many achieve successful pregnancies. If there are any abnormalities with the embryo, then a chemical pregnancy may take place. A study, published in the Journal of Clinical Medicine Research, states that women who completed one round of IVF without any chemical pregnancy were more likely to achieve success the second time as well.

How is a chemical pregnancy treated?

Chemical pregnancies normally resolve spontaneously without any medical intervention needed, however, follow-up helps in full recovery and exclusion of any other health issues by a healthcare provider. If a woman is undergoing multiple chemical pregnancies, then the doctor can provide tests to determine the cause and treat the cause. One should also go for emotional support counselling as these might also benefit those affected in this way.

Also read: Miscarriage after care is essential: 7 things you must do!

A pregnant woman lying down during an ultrasound
Chemical pregnancies cannot be prevented. Image courtesy: Pexels

Can you prevent a chemical pregnancy?

Preventing a chemical pregnancy can be difficult as many causes like chromosomal abnormalities are beyond one’s control. To reduce this risk, it might help to stay healthy, live with chronic diseases and advice from doctors when trying to have children. Early monitoring through regular prenatal care is important to deal with any potential problems.

Who is more at risk of a chemical pregnancy?

Chemical pregnancies are more likely for women above thirty-five years, especially if they already had miscarriages in the past or have hormonal and malformation disorders such as those related to the uterus or ovary. Also, women who have thyroid problems or uncontrollable diabetes may experience chemical pregnancies frequently. Additionally, other factors like smoking, excessive alcohol intake and high levels of stress can cause this condition too.


A chemical pregnancy is a very early miscarriage, usually in the first five weeks of pregnancy. While there is no way to avoid this, the cause of frequent chemical pregnancies must be evaluated by a doctor. Many reasons cause chemical pregnancies such as hormonal imbalances or infections.

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