What is a chemical pregnancy and how do you know if you've had one?

·4-min read
Photo credit: Getty Images
Photo credit: Getty Images

The NHS estimates that around one in eight pregnancies end in miscarriage. But despite so many people experiencing them, so few of us actually know about the different types of miscarriage that could occur, like a missed miscarriage or a chemical pregnancy – the latter being a very common form of early pregnancy loss. In fact, some people may have experienced a chemical pregnancy without even knowing.

But what actually is a chemical pregnancy? What causes a chemical pregnancy? And how do you know if you've had one? To answer those questions, we spoke to Dr Deborah Lee at Dr Fox Online Pharmacy.

What is a chemical pregnancy?

"When you hear the term chemical pregnancy, this is actually short for 'biochemical pregnancy'," Dr Lee tells us. "This means that you have a positive pregnancy test, but there are no detectable signs of the pregnancy in the uterus (womb). A chemical pregnancy is a very common form of early pregnancy loss, which occurs in the first five weeks of pregnancy."

Going into more detail about chemical pregnancy, Dr Lee says that to understand chemical pregnancy better, we need to "go back to what happens to create a pregnancy."

"At the moment of conception, when sperm and egg fuse, they form a ball of cells called a blastocyst. In order to grow and develop, the blastocyst has to attach to the lining of the womb (the endometrium) via the placenta," the expert explains. "During these very early days, the placenta starts to produce a hormone called B Human Chorionic Gonadotrophin (BHCG). A pregnancy test looks for the presence of BHCG in the urine and if BHCG is present, the test will show as positive."

Photo credit: Getty Images
Photo credit: Getty Images

As for how this becomes a chemical pregnancy, Dr Lee adds: "In a chemical pregnancy, BHCG is detectable in the urine, so the pregnancy test is positive, but the blastocyst, for some reason, is unable to grow and develop. As a result, in the first few weeks after conception, the gestation sac does not develop, and cannot be seen on an ultrasound scan. The gestation sac is vital as the embryo grows within it throughout the rest of the pregnancy. Without a sac being present, there can be no intrauterine pregnancy."

Chemical pregnancy symptoms

If you think you may have had a chemical pregnancy, or may be experiencing one, Dr Lee tells us there are a number of signs and symptoms to look out for. These include:

  • A positive pregnancy test before or around the time your next period was due

  • Spotting in the week before your period was due

  • Mild cramping and low abdominal pain

  • Vaginal bleeding that started after your positive test

  • Your BHCG levels are lower than would be expected (confirmed by a blood test)

  • You have a period which is heavier than usual, may be more painful and you may pass clots

However, the expert points out that "some women bleed in a healthy pregnancy around the time of implantation."

What causes a chemical pregnancy?

While there's no way to predict whether or not you'll have a chemical pregnancy, Dr Lee notes that chemical pregnancies are thought to be due to:

  • Chromosomal abnormalities - the embryo may have too many or too few chromosomes due to abnormal chromosomes in the sperm or egg, or abnormal cell division after fertilisation

  • A thin endometrium (womb lining) - this needs to be thick and healthy to supply the developing blastocyst with the necessary nutrients for development

She also adds that chemical pregnancies are more common in people aged 35 and over, those with untreated blood clotting conditions, those with thyroid disease and those with type 2 diabetes.

Photo credit: Mario Arango - Getty Images
Photo credit: Mario Arango - Getty Images

What can you do to reduce your chance of a chemical pregnancy?

The answer to that question, Dr Lee tells us, is unfortunately "very little." Chemical pregnancies are "probably quirks of nature," she adds. However, she also advises:

  • Try and reduce your stress levels – some studies have shown that stress can increase the risk of early miscarriage

  • Eat a healthy diet full of fruit and vegetables

  • Take folic acid 400 mcg a day before trying to get pregnant and in the first 12 weeks of pregnancy

  • Don’t smoke or drink alcohol

  • Take advice about how to improve the quality of your partner’s sperm

How to cope after a chemical pregnancy

"Women may still grieve for a chemical pregnancy," Dr Lee points out. "This may have been a much longed for positive pregnancy test, and the knowledge that it is not a healthy pregnancy and will not result in a baby, can be very hard to bear," she adds, directing anyone who's suffering after a pregnancy loss to reach out to Tommy's, the baby loss charity.

If you're looking for support or more information about premature births, stillbirths or miscarriage, Tommy's have a free helpline 0800 0147 800 (open 9-5, Monday to Friday). There's also a Facebook group.

This article is not intended to be a substitute for professional medical advice or diagnosis. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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