A blighted ovum is a type of very early miscarriage that happens when a fertilized egg never develops into an embryo or an embryo stops growing shortly after implantation. You might find out about it at an early prenatal appointment, and you may or may not have symptoms.
If you’re diagnosed with blighted ovum, it’s natural to feel confused and upset. Read on to learn more about this type of miscarriage.
What is a blighted ovum?
A blighted ovum, also known as an anembryonic pregnancy, occurs when something goes wrong shortly after conception. After an egg is fertilized and implants in the uterus, a placenta begins to develop — but an embryo does not.
In a typical pregnancy, a sperm fertilizes an egg shortly after ovulation. Within hours, the fertilized egg starts dividing and eventually forms an embryo. Implantation triggers the placenta to start developing and hormone levels to rise. The embryo keeps growing and can usually be seen on an ultrasound around week 5 to week 6 of pregnancy.
Doctors can diagnose a blighted ovum using ultrasound starting at around week 7 of pregnancy. Imaging will show a gestational sac that's smaller than expected, with no visible embryo.
What to Expect Community member Melbloomingrose says she "found out from the ultrasound when I was supposed to be 9 weeks. I miscarried naturally about a week later."
What causes a blighted ovum?
Like most early miscarriages, a blighted ovum is often caused by chromosomal abnormalities. Research suggests that more than two-thirds of blighted ovum miscarriages involve genetic issues. The fertilized egg may have extra or missing chromosomes, meaning it doesn't have the right genetic material to develop normally.
Ultimately, a blighted ovum is the body's way of ending a pregnancy that isn't developing properly. It's important to know that there's nothing you or your partner did to cause it, and there's nothing you could have done to prevent it.
What are the symptoms of blighted ovum?
You may not have symptoms and only learn about a blighted ovum during an ultrasound at a prenatal appointment. If you do have symptoms, they will typically be those of a miscarriage, and may come after you've had early pregnancy symptoms.
A blighted ovum can initially feel like a normal pregnancy. That’s because the body still produces pregnancy hormones (including hCG, the hormone that's detected on a pregnancy test), which can lead to symptoms such as morning sickness, sore breasts, and bloating. Many women also get a positive pregnancy test.
"I was so confused because I had no bleeding and had all the pregnancy symptoms. I felt blindsided," says Community member sxn9.
When the fertilized egg fails to develop into an embryo, hCG levels begin to drop and pregnancy symptoms fade. At this point, signs of miscarriage — such as bleeding and cramping — may occur.
Symptoms of blighted ovum may include:
- Heavy bleeding. Light spotting can be normal early in pregnancy, but see your health care provider if you have heavier bleeding, similar to a period.
- Severe cramping. Some cramping during pregnancy can be normal, but stronger or persistent cramps, especially with bleeding or fever, should be checked out. Cramping can point to other pregnancy complications, including an ectopic pregnancy, that may require medical attention.
- An abnormal ultrasound. Your doctor will see a smaller gestational sac than expected that contains no embryo.
- Lower hCG levels. Blood tests show lower levels of the pregnancy hormone hCG starting at about 6 to 8 weeks of pregnancy in anembryonic pregnancies.
A blighted ovum can only be confirmed with an ultrasound, which shows that a fertilized egg hasn’t developed into an embryo. An ultrasound also helps rule out other conditions, such as an ectopic pregnancy, which requires prompt medical treatment.
If you’re not sure about the first day of your last period and an embryo isn't apparent at your ultrasound, your practitioner may ask you to come back in a week for a follow-up ultrasound.
Keep track of your symptoms, get expert advice, and connect with other women with similar experiences in the What to Expect app.
How common is a blighted ovum?
Blighted ovum is the most common cause of miscarriage. Experts estimate that blighted ovum accounts for about 50% of all first trimester miscarriages. About 15% of all pregnancies end in miscarriage before 13 weeks of pregnancy.
Because these losses happen so early, not all cases are diagnosed, making exact numbers difficult to determine.
How is a blighted ovum treated?
If you have a blighted ovum, treatment involves making sure the uterus is emptied of pregnancy tissue. There are several ways to do this, and your doctor can help you consider the options:
- Expectant management. Your body may naturally pass the tissue on its own, with bleeding similar to a heavy period. Doctors often recommend waiting several days to a week to see if this happens.
- Medication. Your practitioner may prescribe a medication to help the uterus expel its contents. "I took misoprostol around 9 weeks, and it passed quickly," says What to Expect Community member waterplove. "I got pregnant soon after with my now 1-year-old."
- Surgery. A brief surgical procedure called a dilation and curettage (D&C) can be performed to remove the tissue. "It's a very quick and easy procedure and faster emotionally than miscarrying naturally," says Community member Shelby312.
How will a blighted ovum affect my chances of getting pregnant again?
The odds are good that you'll go on to have a healthy pregnancy following a blighted ovum.
While any pregnancy loss can be heartbreaking, it may help to keep in mind that most women only have one miscarriage before going on to having a healthy baby. And the type of treatment following the loss doesn’t affect your odds of conceiving in the future.
"I had a blighted ovum and 6 months later a healthy pregnancy," says What to Expect Community mom lpease44.
Only about 1% of women have recurrent losses. If you have multiple blighted ovum pregnancies, your practitioner may recommend testing to check for underlying causes, such as a hormonal imbalance or genetic condition.
A blighted ovum can be an unexpected and emotional experience, especially if you were already adjusting to the idea of being pregnant. While it may not make the loss easier, understanding that it’s a common and unpreventable type of early miscarriage can offer some reassurance. Most importantly, it doesn’t define your fertility — your chances of having a healthy pregnancy in the future remain very strong.
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