What Is a Blighted Ovum (Anembryonic Pregnancy)? Causes and Meaning in IVF

A positive pregnancy test is a moment of great joy for most couples. Yet sometimes, an ultrasound performed a few weeks later reveals an unexpected picture: a gestational sac is visible, but there is no embryo inside it. This is known as a blighted ovum, or in medical terms an anembryonic pregnancy. In this article we explain what a blighted ovum is, its causes, its signs, and its place in IVF treatment — with medical accuracy and empathy.

What Is a Blighted Ovum (Anembryonic Pregnancy)?

A blighted ovum is a situation in which fertilisation occurs, the embryo implants in the uterine wall and a gestational sac forms, but the embryo either fails to develop or stops developing at a very early stage. Because the pregnancy hormone (beta hCG) can keep rising for a while, the body and the pregnancy test respond as if a genuine pregnancy is present. On ultrasound, an embryo and heartbeat are usually expected from around weeks 7-8; in a blighted ovum, the sac may have grown but no embryo, yolk sac or heartbeat is seen at this stage.

A blighted ovum is one of the most common causes of early pregnancy loss (miscarriage) and usually occurs in the first trimester, often when a woman has only just learned she is pregnant.

Why Does a Blighted Ovum Happen? Whose Fault Is It?

This is the question couples ask most and worry about most: “What caused it, who is responsible?” There is a clear answer: a blighted ovum is not the “fault” of the woman or the man. It is a biological event that no one could have prevented.

The main known causes are:

• Chromosomal abnormalities: In the large majority of blighted ova, an irregularity arises in the number or structure of the embryo’s chromosomes when egg and sperm combine. This irregularity prevents the embryo from developing normally, and the body does not carry the pregnancy forward.
• Abnormalities during fertilisation: Unpredictable cellular problems arising at the moment of fertilisation, related to egg or sperm quality, can also prevent the embryo from developing.
• Maternal age: As a woman’s age increases, so does the rate of chromosomal abnormalities in the eggs. For this reason the risk of a blighted ovum rises statistically with advancing maternal age.

It must be stressed here: these causes do not stem from any behaviour, mistake or shortcoming that the woman or man could have controlled. It is not related to lifestyle, stress or “doing something wrong.” Chromosomal abnormalities are a natural and random part of reproductive biology.

What Are the Signs of a Blighted Ovum?

A blighted ovum has no unique, distinguishing symptom; it usually begins like a normal early pregnancy. Some signs that may be noticed include:

• The pregnancy test is positive and early-pregnancy symptoms (nausea, breast tenderness, fatigue) may be experienced for a time.
• These symptoms may gradually fade or disappear completely; for some women this is the first warning sign.
• In blood tests, the beta hCG level may rise at first but not increase at the expected rate, may stay low, or may plateau and then begin to fall.
• On ultrasound, a gestational sac is seen, but despite the expected week, no embryo, yolk sac or heartbeat is detected inside it.
• Some women also experience spotting or light bleeding; however, many blighted ova cause no physical symptoms at all and are only noticed on a routine ultrasound.

A definitive diagnosis is not made from a single ultrasound but usually through repeated ultrasound and beta hCG monitoring a few days or weeks apart. This is important to allow enough time for the embryo to develop and to avoid reaching a wrong conclusion.

Can a Blighted Ovum Occur in IVF?

Yes, a blighted ovum can occur in pregnancies achieved after IVF treatment, just as it can in naturally conceived pregnancies. Even after embryo transfer has succeeded and the pregnancy test is positive, development can stop for reasons related to the embryo’s chromosomal make-up, and a blighted ovum can result.

An important point must be clarified here: a blighted ovum does not mean the IVF treatment has failed. The treatment process achieved the transfer of the embryo, its implantation in the uterine wall and the start of the pregnancy. Development beyond this point depends on the embryo’s own biological potential — the same dynamics as in natural pregnancies. IVF does not change the embryo’s genetic make-up; it only supports the fertilisation and transfer process.

For this reason we always remind our patients who experience a blighted ovum: this is not a “failure” related to the body’s response to treatment or to the clinic’s protocol; it is a natural obstacle encountered in the embryo’s own developmental journey.

What Happens After a Blighted Ovum?

Once the diagnosis is confirmed, your doctor will determine the most appropriate approach together with you:

• Watch-and-wait approach: In some cases the body passes the pregnancy tissue on its own.
• Medication: Medication may be recommended to support the process.
• Dilation and curettage (D&C): If considered necessary, the pregnancy tissue is removed with a minor surgical procedure. This can also allow the tissue to be examined for chromosomal analysis.

After the procedure, it takes some time for hormone levels to return to normal, and this process is monitored by the doctor. When you can start trying to conceive again varies from person to person; your doctor will suggest a timing tailored to your body’s recovery.

The majority of couples who experience a blighted ovum go on to achieve a healthy pregnancy in due course. For couples with recurrent pregnancy loss, the doctor may raise the option of genetic testing (PGT) to assess the embryo’s chromosomal make-up before transfer. PGT is not a method applied automatically to every patient or every treatment cycle; whether it is suitable is determined in line with your history and medical assessment.

Do Not Overlook the Emotional Process

Although a blighted ovum is medically considered an “early” loss, emotionally it is a real and profound loss. For a couple who had built hope and made plans, this news can bring a heavy period of grief. There is no reason to blame yourself or ask “what did I do wrong”; as explained above, this is a biological process no one can control.

Giving yourself time, communicating openly with your spouse or partner, and seeking psychological support when needed all play an important part in your recovery. Do not hesitate to share your emotional concerns with your care team as well; you deserve answers to your questions with a human approach as much as a medical one.

If you have experienced a blighted ovum or have questions about it, the GynoLife IVF team is here to listen and to provide information specific to your situation. You can contact GynoLife to request a consultation and plan your next steps together.

If you are experiencing recurrent pregnancy loss or have questions about your IVF journey, contact us for a personalised assessment from GynoLife’s specialist medical team.