What Is Blighted Ovum and Anembryonic Pregnancy?

Few pregnancy losses are as confusing and emotionally complicated as blighted ovum. You have all the signs of pregnancy: the positive test, the missed period, the nausea and breast tenderness. You’re pregnant, except that you’re not, or not in the way you thought. An ultrasound reveals a gestational sac where a baby should be growing, but the sac is empty. There’s no embryo developing inside.

The medical term is anembryonic pregnancy, meaning a pregnancy without an embryo. The older term, blighted ovum, sounds harsh and outdated but is still commonly used. Regardless of terminology, this condition represents one of the most common causes of first-trimester miscarriage, responsible for about half of all pregnancy losses before 12 weeks. That’s thousands of women every year experiencing this particular form of loss, grieving a pregnancy that never fully began.

Understanding what blighted ovum is, why it happens, how it’s diagnosed, and what comes next doesn’t make the experience less painful. But it does provide clarity about what went wrong, why, and what it means for future pregnancies. This article examines the medical reality of anembryonic pregnancy while acknowledging that behind every clinical explanation is someone processing loss and uncertainty.

What Happens in a Blighted Ovum?

Blighted ovum isn’t a complete failure of conception. Fertilization occurs normally, and initial steps of pregnancy proceed as they should. The breakdown happens during early development when the embryo should form.

The Normal Early Development Process

In a typical pregnancy, a sperm fertilizes an egg, creating a single cell with complete genetic instructions. This cell divides repeatedly as it travels down the fallopian tube toward the uterus. By the time it reaches the uterus about five to six days after fertilization, it’s become a blastocyst, a hollow ball of cells with an inner cell mass that will become the embryo and an outer layer that will become the placenta.

The blastocyst implants into the uterine lining, usually 6 to 10 days after ovulation. After implantation, the outer cells begin secreting human chorionic gonadotropin, or hCG, the hormone detected by pregnancy tests. The inner cell mass should develop into an embryo, with a yolk sac providing nutrition until the placenta takes over.

By five to six weeks of pregnancy, counting from the first day of the last menstrual period, a transvaginal ultrasound should show a gestational sac. By six weeks, a yolk sac should be visible. By six to seven weeks, an embryo with a detectable heartbeat should appear.

What Goes Wrong in Anembryonic Pregnancy

In blighted ovum, fertilization and implantation occur normally. The outer cells develop and begin forming the gestational sac and placenta. HCG is produced, causing positive pregnancy tests and pregnancy symptoms. But the inner cell mass that should become the embryo never develops or stops developing very early, leaving an empty gestational sac.

The pregnancy continues producing hCG for a time because the placental tissue keeps developing even without an embryo. This is why pregnancy tests remain positive and pregnancy symptoms persist initially. But eventually, without an embryo present, the pregnancy can’t continue and ends in miscarriage.

Why the Term “Blighted” Is Problematic

The word “blighted” suggests something diseased or spoiled, implying that something went wrong with an otherwise viable pregnancy. But anembryonic pregnancy isn’t about a healthy embryo being damaged. The embryo never formed correctly from the beginning due to fundamental genetic problems. The term “anembryonic pregnancy” is more accurate and less loaded with negative connotations, though “blighted ovum” remains widely used and recognized.

How Common Blighted Ovum Is and Who It Affects

Blighted ovum isn’t rare. It’s one of the most common reasons for early pregnancy loss, though many people have never heard of it until experiencing it themselves.

Prevalence Among First-Trimester Miscarriages

Research consistently shows that blighted ovum accounts for approximately 50% of first-trimester miscarriages. Given that early pregnancy loss occurs in about 10% of clinically recognized pregnancies, and most of those losses happen in the first trimester, blighted ovum affects a substantial number of pregnancies.

Overall, blighted ovum is responsible for roughly one-third of all miscarriages across all trimesters, though it occurs almost exclusively in the first trimester since the pregnancy cannot continue beyond that point without an embryo.

Why Many Women Don’t Know About It

Despite being common, blighted ovum isn’t widely discussed or understood for several reasons:

• Many early miscarriages occur before ultrasound confirmation, so the specific cause isn’t identified
• Some women miscarry naturally before having an ultrasound that would diagnose blighted ovum
• Miscarriage in general remains somewhat taboo, with less open discussion than other pregnancy topics
• Medical terminology is confusing and the condition isn’t explained in typical pregnancy education

This means many women experiencing blighted ovum feel isolated, unaware that it’s a common occurrence affecting thousands annually.

Risk Factors and Who Is More Affected

While blighted ovum can happen to anyone, certain factors increase risk:

Advanced maternal age, particularly over 35, correlates with higher rates of chromosomal abnormalities that cause blighted ovum. Obesity has been associated with increased risk of early pregnancy loss including anembryonic pregnancy. Previous miscarriage slightly increases the chance of subsequent losses, though most women go on to have successful pregnancies.

However, many women experiencing blighted ovum have no identifiable risk factors. It often occurs in healthy women with no prior pregnancy complications.

The Genetic Causes Behind Most Blighted Ova

Understanding why blighted ovum happens requires looking at what goes wrong at the chromosomal level.

Chromosomal Abnormalities as the Primary Cause

The overwhelming majority of blighted ova result from chromosomal abnormalities in the fertilized egg. These are errors in the number or structure of chromosomes present in the embryo.

Human cells normally contain 46 chromosomes arranged in 23 pairs. When sperm and egg form, they undergo a process called meiosis that should give each cell exactly 23 chromosomes. When sperm and egg unite, the resulting embryo should have the correct 46 chromosomes.

Errors during meiosis can result in eggs or sperm with too many or too few chromosomes. When these fertilize, the resulting embryo has an abnormal chromosome number, a condition called aneuploidy. Most aneuploidies are incompatible with development, preventing the embryo from forming even though the placental tissue develops initially.

Trisomy 16 and Other Specific Abnormalities

Trisomy 16, where there are three copies of chromosome 16 instead of two, is particularly common in blighted ovum cases. This abnormality is always lethal, preventing embryo development.

Other chromosomal abnormalities causing blighted ovum include:

• Monosomy X, where only one sex chromosome is present
• Various other trisomies
• Triploidy, where there are three complete sets of chromosomes instead of two
• Structural chromosomal abnormalities

These genetic errors are essentially nature’s quality control mechanism. Embryos with these severe abnormalities cannot develop into healthy babies, and pregnancy ends early rather than continuing with no possibility of success.

Why Chromosomal Errors Occur

Chromosomal abnormalities happen randomly during cell division and increase with maternal age. As eggs age, the cellular machinery that separates chromosomes during meiosis becomes less reliable, leading to higher rates of chromosomal errors.

This isn’t something that can be prevented through diet, supplements, or lifestyle changes. It’s a fundamental biological process that occurs more frequently as reproductive cells age.

Other Genetic and Developmental Factors

Beyond chromosomal abnormalities, other factors can contribute:

• Sperm DNA damage affecting embryo development
• Genetic mutations preventing normal embryo formation
• Problems with gene expression in early development

These are less common than chromosomal abnormalities but can prevent embryo development even when chromosome numbers are normal.

Non-Genetic Risk Factors for Anembryonic Pregnancy

While chromosomal abnormalities cause most blighted ova, other factors can contribute to risk or create conditions where early pregnancy loss is more likely.

Hormonal Imbalances Affecting Early Pregnancy

Adequate progesterone is essential for maintaining early pregnancy. Progesterone prepares the uterine lining for implantation and supports the pregnancy until the placenta develops sufficiently to sustain it.

Low progesterone levels, whether from inadequate ovarian production or luteal phase defects, can contribute to early pregnancy loss. However, progesterone deficiency more commonly causes early miscarriage with an embryo present rather than specifically causing blighted ovum.

Thyroid disorders, particularly hypothyroidism, can affect pregnancy maintenance. Uncontrolled thyroid disease increases miscarriage risk generally.

Uterine Abnormalities and Structural Issues

Certain uterine malformations can increase early pregnancy loss risk:

• Septate uterus, where a wall of tissue divides the uterine cavity
• Bicornuate uterus, where the uterus has two separate cavities
• Uterine fibroids, particularly those that distort the uterine cavity
• Asherman’s syndrome, where scar tissue forms inside the uterus

These structural problems may interfere with implantation or early pregnancy support, though they don’t specifically cause the failure of embryo development that defines blighted ovum.

Infections and Immune Factors

Certain infections can increase miscarriage risk:

• Untreated sexually transmitted infections
• Severe systemic infections
• Specific infections like toxoplasmosis or listeria

Immunological disorders where the immune system attacks the pregnancy can cause pregnancy loss, though these typically cause later losses rather than the very early developmental failure of blighted ovum.

Lifestyle Factors and Environmental Exposures

Research has identified several modifiable risk factors:

• Alcohol consumption, even in small amounts, increases miscarriage risk. No safe level of alcohol during pregnancy has been established.
• Smoking cigarettes damages eggs and affects implantation and early pregnancy development.
• Extreme obesity affects hormone levels and increases miscarriage risk through multiple mechanisms.
• Environmental toxins and certain medications can affect early pregnancy, though most blighted ova occur despite healthy lifestyle choices.

Signs and Symptoms of Blighted Ovum

The symptoms of blighted ovum can be confusing because they mimic normal early pregnancy initially before changing as the pregnancy fails.

Early Pregnancy Symptoms That Occur Initially

Women with blighted ovum typically experience normal early pregnancy symptoms because the placental tissue is producing hCG and pregnancy hormones:

• Missed menstrual period
• Positive pregnancy tests
• Nausea and morning sickness
• Breast tenderness and swelling
• Fatigue
• Frequent urination
• Mild cramping similar to early normal pregnancy

These symptoms feel exactly like any other pregnancy, which is why blighted ovum is often discovered unexpectedly during an ultrasound rather than because symptoms suggested a problem.

The Disappearance of Pregnancy Symptoms

As the pregnancy begins failing, usually between 7 and 12 weeks, pregnancy symptoms often fade:

• Nausea suddenly improves or disappears
• Breast tenderness decreases
• The feeling of “being pregnant” diminishes

Some women notice these changes and become concerned. Others don’t notice or attribute the changes to entering the second trimester when symptoms typically improve anyway. The fading symptoms result from declining hCG levels as the placental tissue stops developing.

Signs of Impending Miscarriage

Eventually, the body recognizes the pregnancy isn’t viable and begins the miscarriage process:

• Vaginal spotting or bleeding, often starting light and becoming heavier
• Cramping and pelvic pain as the uterus contracts
• Tissue or clots passing vaginally
• Sometimes flu-like symptoms

The timing varies. Some women begin miscarrying within days of diagnosis, while others continue carrying an anembryonic pregnancy for weeks before miscarriage occurs.

When There Are No Symptoms At All

A substantial number of blighted ova are discovered during routine first-trimester ultrasounds in women with no symptoms suggesting a problem. The pregnancy continues, symptoms persist, and there’s no bleeding or cramping. Only the ultrasound reveals the absence of an embryo.

This can be particularly shocking, making the loss feel more sudden despite having occurred weeks earlier when the embryo failed to develop.

How Blighted Ovum Is Diagnosed With Ultrasound

Diagnosis of blighted ovum requires ultrasound imaging showing specific findings that confirm no embryo has developed.

What Ultrasound Shows in Anembryonic Pregnancy

Transvaginal ultrasound, where a probe is inserted into the vagina for closer imaging, provides the clearest views of early pregnancy. In blighted ovum, ultrasound shows:

• A gestational sac, the fluid-filled structure that should contain the developing embryo
• An empty gestational sac with no embryo visible inside
• Sometimes a yolk sac, but no embryonic pole or fetal heartbeat
• A gestational sac measuring larger than expected for an empty sac

The critical finding is a gestational sac of sufficient size without any embryo present. Specific size criteria exist to ensure the sac is large enough that an embryo should definitely be visible if present.

Timing and Measurement Criteria

Diagnosis requires careful assessment because dating errors could mean the pregnancy is simply younger than thought:

Gestational sac measuring 25mm or larger without an embryo confirms blighted ovum. At this size, an embryo should definitely be visible. A mean sac diameter of 18-24mm without an embryo, combined with other findings, strongly suggests blighted ovum but may warrant repeat ultrasound to be certain.

Following embryo should be visible by six to seven weeks gestational age based on last menstrual period, assuming regular 28-day cycles.

Why Repeat Ultrasound Is Sometimes Needed

To avoid misdiagnosing a normal but younger-than-expected pregnancy as blighted ovum, providers sometimes recommend repeat ultrasound in one to two weeks if:

• Dating is uncertain and the sac is borderline size
• The measurement is close to diagnostic thresholds
• The woman isn’t ready to proceed with management
• There’s any possibility of dating error

A repeat scan showing no embryo development despite sac growth, or showing sac shrinkage, confirms the diagnosis.

Other Diagnostic Tests

Serial hCG measurements can provide supporting evidence. In normal pregnancy, hCG should double approximately every 48 hours in early pregnancy. In blighted ovum:

• HCG rises initially but eventually plateaus or falls
• HCG levels may be lower than expected for gestational age
• The pattern suggests pregnancy failure

However, ultrasound findings are definitive. HCG measurements alone can’t distinguish blighted ovum from other early pregnancy complications.

Treatment Options After Blighted Ovum Diagnosis

Once blighted ovum is confirmed, several management approaches are available. The choice depends on medical factors, patient preference, and individual circumstances.

Expectant Management and Waiting for Natural Miscarriage

Expectant management means waiting for the body to naturally miscarry the pregnancy tissue. This approach involves:

• No medical intervention
• Waiting days to weeks for bleeding and cramping to begin
• Passing tissue at home
• Follow-up to ensure complete miscarriage

Advantages include avoiding medical interventions, maintaining a sense of natural process, and no medication side effects or surgical risks.

Disadvantages include uncertainty about when miscarriage will occur, potentially heavy bleeding requiring emergency care, and extended emotional distress while waiting.

Not all women miscarry completely with expectant management. Some require subsequent medical or surgical intervention if tissue remains.

Medical Management With Medication

Medical management uses medications, typically misoprostol, to induce miscarriage:

• Misoprostol causes uterine contractions to expel pregnancy tissue
• It’s taken orally or vaginally, sometimes in multiple doses
• Cramping and bleeding begin within hours to days
• Most tissue passes within 24-48 hours

Advantages include avoiding surgery, more control over timing than expectant management, and ability to manage at home.

Disadvantages include cramping and bleeding that can be heavy, potential need for pain medication, and small chance of incomplete miscarriage requiring additional treatment.

Success rates are generally 80-90% for complete miscarriage with medical management in first-trimester losses.

Surgical Management With D&C

Dilation and curettage, or D&C, is a surgical procedure removing pregnancy tissue:

• The cervix is dilated
• Tissue is removed with suction and scraping
• The procedure takes 10-15 minutes
• It’s done under sedation or anesthesia
• Recovery is typically rapid

Advantages include immediate completion, ability to obtain tissue for genetic testing if desired, and knowing the process is finished.

Disadvantages include surgical risks like infection or uterine perforation, potential complications from anesthesia, and cost if not covered by insurance.

D&C provides certainty and closure for some women who don’t want to wait for natural miscarriage or take medication.

Factors Influencing Management Choice

The decision depends on multiple considerations:

• How far along the pregnancy is
• Patient preference and emotional needs
• Desire to avoid surgery versus desire for immediate resolution
• Bleeding risk and patient health factors
• Access to emergency care if needed
• Insurance coverage and financial factors
• Cultural or religious beliefs

No option is inherently better. The right choice is the one that feels most appropriate for the individual’s circumstances.

The Emotional Impact of Blighted Ovum

Beyond the medical facts, blighted ovum creates a unique emotional experience that deserves acknowledgment and validation.

The Confusion of a Pregnancy That Never Was

Blighted ovum occupies strange emotional territory. You were pregnant, with positive tests and symptoms confirming it. You began making mental adjustments and plans. Then you discover there was never an embryo developing, never a baby-to-be in any real sense.

This can create confusing grief. Some women question whether they should mourn what never existed. Others feel guilty about grieving a “pregnancy” rather than a baby. Some face dismissive responses suggesting this type of loss isn’t as significant as later losses.

These feelings are valid and the loss is real. The pregnancy and the hopes associated with it existed, even if the embryo didn’t.

Processing Medical Information While Grieving

Receiving a blighted ovum diagnosis means processing complex medical information about chromosomes, ultrasound findings, and management options while emotionally reeling from unexpected loss. Many women describe feeling overwhelmed, unable to fully understand or remember what providers told them.

It’s okay to ask for written information, bring a support person to appointments, request repeat explanations, or take time before making management decisions.

The Question of What Went Wrong

Many women fixate on what they might have done to cause blighted ovum, reviewing recent weeks for potential causes. Did that glass of wine before knowing about pregnancy cause this? The exercise class? The stress at work?

The answer is almost certainly no. Blighted ovum results from chromosomal abnormalities that occurred at fertilization or shortly after. These aren’t caused by anything the mother did or didn’t do. They’re random events reflecting the reality that many fertilized eggs have genetic errors incompatible with development.

Moving Forward After Loss

Recovery from blighted ovum includes both physical recovery from miscarriage and emotional healing from loss:

• Physical recovery typically takes a few weeks
• Emotional healing takes longer and varies greatly between individuals
• Some women want to try again immediately
• Others need time to process the loss before considering another pregnancy
• Counseling or support groups can help some women process grief

There’s no timeline for when someone “should” feel better or be ready to try again.

Future Pregnancy After Blighted Ovum

One of the first questions women ask after blighted ovum is what this means for future pregnancies.

Most Women Go On to Have Successful Pregnancies

The single most important fact about blighted ovum and future fertility is that most women who experience it go on to have successful pregnancies. A single blighted ovum doesn’t indicate an ongoing problem or predict future losses.

Chromosomal abnormalities that cause most blighted ova are random events. They don’t typically recur. Each new pregnancy is essentially starting fresh with new eggs and sperm, each with its own independent chance of chromosomal normality.

When to Try Again After Miscarriage

Physical recovery from miscarriage typically takes two to six weeks. Menstrual cycles usually resume within four to six weeks, sometimes sooner.

Medically, most providers advise waiting for one normal menstrual period before trying to conceive again. This timing allows:

• The uterine lining to fully recover
• Hormones to return to normal levels
• More accurate dating of subsequent pregnancy
• Emotional processing time

Some research suggests pregnancy immediately after miscarriage has similar or even slightly better outcomes than waiting longer, so the one-cycle wait is about practical timing rather than medical necessity.

The decision about when to try again should consider emotional readiness as much as physical recovery.

Risk of Recurrence and When Further Testing Is Warranted

After one blighted ovum, the chance of experiencing another is not significantly elevated. The vast majority of women have successful subsequent pregnancies.

After two or three consecutive pregnancy losses of any type, testing for recurrent pregnancy loss causes is typically recommended. This might include:

• Chromosomal analysis of both partners
• Testing for blood clotting disorders
• Evaluation of uterine anatomy
• Hormone level assessments
• Sometimes testing for autoimmune conditions

After a single blighted ovum, extensive testing isn’t indicated unless there are other specific concerns.

Genetic Counseling and Testing Options

For women concerned about recurrence or who’ve had multiple losses, genetic counseling can provide:

• Assessment of whether genetic factors might be involved
• Discussion of testing options for future pregnancies
• Information about prenatal testing and diagnosis
• Risk assessment based on personal and family history

Preimplantation genetic testing during IVF can screen embryos for chromosomal abnormalities before transfer, though this invasive and expensive approach isn’t typically recommended after single blighted ovum.

Questions to Ask Your Healthcare Provider

When facing a blighted ovum diagnosis, certain questions can help clarify the situation and guide decisions.

Questions About Diagnosis Confirmation

• How certain is the diagnosis based on ultrasound findings?
• Is repeat ultrasound recommended before proceeding with treatment?
• What measurements were used to confirm the absence of an embryo?
• Is there any possibility of dating error?

These questions ensure the diagnosis is definitive before making management decisions.

Questions About Management Options

• What are all the management options available?
• What are the success rates, risks, and benefits of each approach?
• What should I expect with each option in terms of pain, bleeding, and timeline?
• Are there medical factors that make one option preferable for me?
• What pain management is available for each approach?

Understanding options helps in making informed decisions aligned with preferences.

Questions About Recovery and Follow-Up

• What should I expect during physical recovery?
• When should I call with concerns?
• What symptoms would indicate a problem requiring immediate care?
• When will I have follow-up to ensure complete miscarriage?
• When can I try to conceive again if I want to?

These practical questions guide expectations for the coming weeks.

Questions About Future Pregnancies

• What does this mean for my ability to have children?
• Are there any tests I should have before trying again?
• Is there anything I can do to prevent this from happening again?
• When should I be concerned if I have another loss?

These questions address natural concerns about future fertility.

Moving Forward With Understanding and Hope

Blighted ovum represents one of the most common yet least discussed pregnancy complications, accounting for about half of first-trimester miscarriages. The medical explanation is straightforward: chromosomal abnormalities, particularly trisomy 16, prevent embryo development even though a gestational sac forms and pregnancy hormones are produced. The emotional reality is far more complex, involving grief for a pregnancy that existed but never fully began, confusion about what went wrong, and concern about what this means for future fertility.

The vast majority of women who experience blighted ovum go on to have successful pregnancies. A single anembryonic pregnancy doesn’t indicate an underlying fertility problem or predict future losses. The chromosomal errors causing most blighted ova are random events that don’t typically recur. Physical recovery takes weeks, emotional healing takes longer, and there’s no rush to try again until you’re ready.

What matters now is giving yourself time to process the loss, understanding that grief for a blighted ovum is legitimate and valid, making management decisions aligned with your preferences and circumstances, and knowing that this experience, while painful, is almost certainly not a barrier to future healthy pregnancies. The hope you held for this pregnancy wasn’t misplaced or foolish, even though the outcome wasn’t what you expected. Most women who experience this loss eventually hold the healthy baby they hoped for.