A blighted ovum might almost be described as a pregnancy that never was: it’s a type of miscarriage that occurs when a fertilized egg fails to develop into an embryo.
What is a blighted ovum?
In a normal pregnancy, your partner’s sperm fertilizes your egg after ovulation. This fertilized egg immediately starts dividing, splitting into two cells, then four, then eight, etc. In about 10 days, this growing cluster of cells becomes an embryo contained within a gestational sac and will implant into the uterine wall.
After the process of implantation is complete, the embryo begins to produce the hormone hCG (which is the hormone detected on a positive pregnancy test). The embryo keeps developing, growing enough to become visible on an ultrasound by six weeks of pregnancy (since pregnancy is counted from the date of your last period, six weeks pregnant is the same as about one month after ovulation, or two weeks after your missed period).
In the case of a blighted ovum, embryo development stops during these early weeks. This can happen for a couple of reasons:
- A fertilized egg never develops into an embryo but manages to implant into the uterus anyway.
- An embryo stops developing in the first few days after implantation.
How is a blighted ovum diagnosed?
Some blighted ovums are never diagnosed. You might get a positive pregnancy test followed a few days later by your period. This is a very early miscarriage (also called a chemical pregnancy).
Other women find out about a blighted ovum miscarriage at their first doctor’s appointment. A blighted ovum can be diagnosed on an ultrasound by week seven of pregnancy (about three weeks after your missed period). If there is only an empty gestational sac and no embryo or fetal pole, this is a blighted ovum.
What causes a blighted ovum?
Nothing that you or your partner did caused the blighted ovum, nor anything you could have done to prevent it. In most cases, a blighted ovum miscarriage occurs because of chromosomal abnormalities. In one study that analyzed the chromosomes from 88 blighted ovums, nearly two-thirds were found to have abnormalities such as extra chromosomes or missing chromosomes1.
This means that even though these eggs were fertilized, they never had the genetic material develop into babies. For the one-third of cases where chromosomal abnormalities were not present, it is thought that genetic mutations caused development to halt.
Symptoms of a blighted ovum
Even after the fertilized egg has stopped growing, in many cases your body will respond to a blighted ovum just like a normal pregnancy, continuing to produce the hormones that cause early pregnancy signs and symptoms.
There aren’t always signs that something isn’t right and many women continue to get positive pregnancy tests and experience nausea, bloating, and breast soreness during a blighted ovum. Sometimes, there are signs such as pregnancy spotting, heavy bleeding, or severe cramping.
Recovering from a blighted ovum
Much of the time, your body will recognize early on that a blighted ovum pregnancy is not developing, and you will miscarry naturally. This experience might feel similar to a heavy period, with possible increased cramping. In fact, some women probably experience blighted ovum miscarriages without ever realizing they were pregnant.
If your blighted ovum does not miscarry naturally after a few weeks, your doctor may recommend medication or surgery. You can take a pill called misoprostol, which causes your uterus to clear its contents, or have a brief surgical procedure called a dilation and curettage (D&C).
When can I get pregnant again?
For many women, what helps most with moving on from a miscarriage is getting pregnant again. Usually, there is no reason why you can’t try to get pregnant again right away after a miscarriage. Having a blighted ovum should not affect your chances of conceiving again in the future, and one study even found that for women who conceive within the first six months immediately after a miscarriage, there was a higher likelihood of a healthy, full-term pregnancy2.
And in another study of women with early miscarriages, including blighted ovums, around 80 percent of them gave birth to a healthy baby within five years3. If you have repeat early miscarriages, however, your doctor may recommend testing to make sure there isn’t an underlying issue contributing to the problem.
- “Cytogenetic testing of anembryonic pregnancies compared to embryonic missed abortions” ↩
- Effect of interpregnancy interval on outcomes of pregnancy after miscarriage: retrospective analysis of hospital episode statistics in Scotland ↩
- Incidence of pregnancy after expectant, medical, or surgical management of spontaneous first trimester miscarriage: long term follow-up of miscarriage treatment (MIST) randomised controlled trial ↩