What Is a Chemical Pregnancy?

Getting your period a week after a positive pregnancy test can be confusing and frightening, but it’s actually much more common than you might realize. You may have experienced what’s often referred to as a chemical pregnancy.

Many women who have a chemical pregnancy actually don’t even realize they’ve conceived. But having a chemical pregnancy doesn't indicate that there’s something wrong with you or that you won’t one day give birth to a healthy baby.

What is a chemical pregnancy?

A chemical pregnancy is a very early pregnancy loss that happens when an egg is fertilized and implants in the uterus, but is unable to grow normally. It usually occurs at around week 4 to 5 of your menstrual cycle.

In pregnancy, a fertilized egg implants in the uterine wall about three weeks after the first day of your last menstrual period. Cells that would become the placenta begin to produce levels of the pregnancy hormone hCG (human chorionic gonadotropin) that by the time or your expected period are high enough to detect on a blood or urine test.

With a chemical pregnancy, this implantation does not progress, and the cells don’t develop all the way into an embryo and placenta. This results in bleeding a few days to a week after your regular period was due.

Chemical pregnancies are extremely common. In fact, experts actually believe this very early pregnancy loss may account for up to 50 percent of all conceptions.

Often, the only sign of a chemical pregnancy is a late period. You’ll only know if you had a pregnancy loss if you happened to take an early pregnancy test soon after conception.

Signs of a chemical pregnancy

Many women don’t realize they’ve had a chemical pregnancy. Symptoms that indicate you might have had a chemical pregnancy include:

• An early positive pregnancy test result followed by your period several weeks later
• A late period

Implantation bleeding vs. a chemical pregnancy

Light spotting or bleeding following a positive pregnancy test doesn’t necessarily mean you’re having a chemical pregnancy. Some (but not all) women experience light implantation bleeding, which is a sign that you are pregnant.

On the other hand, heavy bleeding and menstrual-like cramps in pregnancy may indicate an impending early loss.

Either way, if you experience any bleeding after a positive pregnancy test, the American College of Obstetricians and Gynecologists (ACOG) recommends calling your doctor.

What causes a chemical pregnancy?

Most early pregnancy losses, including chemical pregnancies, are caused by chromosomal abnormalities.

At the start of a pregnancy, an egg and a sperm combine 23 chromosomes from each partner to form a zygote with 46 chromosomes. The zygote begins to grow through rapid cell division, evolves into a blastocyst and implants in the uterine wall.

In a chemical pregnancy:

• A sperm or an egg has too many chromosomes or not enough.
• After conception, the resulting zygote (early embryo) also has an abnormal number of chromosomes.
• This chromosomal abnormality causes errors that make it so that the embryo can’t develop normally.

Chromosomal abnormalities occur randomly and can happen to anyone. However, the chance of chromosomal abnormalities increases significantly with age.

Chemical pregnancies definitely don’t mean you won’t be able to get pregnant and stay pregnant in the future.

Chemical pregnancy risk factors

Several risk factors can put you at a higher risk of early pregnancy loss. These include:

• Being 35 or older
• Untreated clotting disorders
• Untreated thyroid conditions
• Other medical conditions, such as uncontrolled diabetes

Chemical pregnancies and IVF 

Chemical pregnancies are also a possibility if you’ve gone through in vitro fertilization (IVF) — and in fact, they can occur quite frequently after IVF or another fertility procedure. But the good news is that an early pregnancy loss like this one can mean a greater chance of conceiving in future IVF cycles as compared with women who have only negative pregnancy tests.

While experiencing a chemical pregnancy after undergoing infertility treatments is certainly disheartening and may even prompt you to stop IVF attempts altogether, the science is on your side. Talk with your doctor about your chances of conception and whether another round of IVF is advised.

While chemical pregnancies do not occur more often with fertility therapies, they tend to be identified more often in this situation, because patients getting fertility therapies are often taking many early pregnancy tests.

Recovery and grief after a chemical pregnancy

A chemical pregnancy may appear more like a cycle in which a pregnancy never occurred than a miscarriage later in pregnancy. But emotionally, it can be a very different story.

It’s natural to feel upset no matter how early a pregnancy loss occurs. Let yourself grieve if you need to.

Remember 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. To get through this tough time, it may help to understand the grieving process, which typically includes several stages such as denial, guilt, anger and even depression. Allow yourself to experience each phase at your own pace.

You might also feel jealousy at the sight of other pregnant women or mothers and babies, and you could experience setbacks during your recovery from a chemical pregnancy. Keep in mind that it’s very normal for feelings to return and fluctuate.

Consider taking some concrete steps as part of your recovery process, including memorializing your baby, finding time for self-care, writing your thoughts in a journal or joining a support group for parents who’ve experienced a similar loss. But if your grief starts to overwhelm or consume your days and prevents you from going about your daily routine, seek help from a counselor or physician.

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 — and hopefully will again soon.

Trying to get pregnant again after a chemical pregnancy

Very early pregnancy losses don’t usually require medical intervention, but you can visit your practitioner if you think you’ve experienced one. They may be able to confirm a chemical pregnancy happened depending on how recently you experienced the bleeding.

Be sure to see your doctor if you’ve noticed that you tend to have an irregular period or a cycle that’s over 35 days long. Your doctor may want to rule out conditions that involve anovulation, like polycystic ovary syndrome (PCOS), that can make it harder for you to get pregnant. They may refer you to a fertility specialist if necessary.

It’s always a good idea to see your doctor if:

• You and your partner are under 35, have no known fertility issues and have been actively trying to conceive for the past 12 months
• You’re over the age of 35 and have been trying to conceive for six months
• You’re over the age of 38 and have been trying to get pregnant for three months
• You’re over the age of 40 or have a personal or family history of infertility

Going through one or two chemical pregnancies can be heartbreaking, but it’s not a cause for alarm. If a medical condition is contributing to your chemical pregnancies, most can be treated so you can go on to conceive a healthy baby. That means that as soon as you feel ready, you can start trying again.