Turner Syndrome (Monosomy X) and Pregnancy Loss

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Turner syndrome (Monosomy X) and pregnancy loss are often related. Turner syndrome is a chromosome disorder in which a girl or woman has only one complete X chromosome. (Because a Y chromosome is needed for a person to be male, all babies with Turner syndrome are girls.) Though girls born with Turner syndrome usually have good odds for a normal life, the majority of babies with the condition are lost to miscarriage or stillbirth.


About 1 in every 2,500 newborn babies have Turner syndrome. Yet according to research, monosomy X is present in 1–2% of all conceptions, but about 99% of affected babies are miscarried or stillborn. The condition is thought to be a factor in roughly 10% of all first trimester miscarriages.


The cause of Turner syndrome is an error in cell division that leaves the body's cells with only one fully functioning X chromosome. Usually, the abnormality is already present at fertilization, originating in the sperm or the egg.

In the condition called Mosaic Turner syndrome, meaning some of the body's cells have monosomy X while others have normal chromosomes, the cause is an error in cell division during very early embryonic development. No one knows exactly what causes these cell division errors.


Turner Syndrome may be revealed as the cause of a miscarriage or stillbirth when parents pursue chromosomal testing after the pregnancy loss. In a current pregnancy, an ultrasound may reveal markers for the condition, but diagnosis can only be confirmed with genetic testing such as amniocentesis or chorionic villus sampling (CVS). And there have been some reports of false positives for the condition, even with amniocentesis.

In newborn babies, the diagnosis can be confirmed with a blood test.

Even though the high risk of miscarriage probably sounds scary, researchers believe that the majority of miscarriages related to Turner syndrome occur in the first trimester. By the time the baby has reached the point of being eligible for an amniocentesis, the odds of pregnancy loss are not nearly as staggering. It can be unnerving to learn that your baby has a chromosome disorder, though, so it's a good idea to get in touch with support groups or a genetic counselor to prepare.


Despite the high risk of miscarriage and stillbirth, the overall prognosis for a baby with Turner syndrome is far from dismal after birth. There are some common health problems and physical characteristics, but girls with Turner syndrome usually have normal intelligence without life-threatening disabilities and can lead happy healthy lives. Many do not even find out that they have the disorder until adulthood.

Role of Genetics in Outcome

If you have lost a baby with Turner syndrome, it is no doubt confusing to hear all the stories of women living with Turner syndrome on one hand, and then, on the other hand, have your doctor tell you that Turner syndrome caused your miscarriage or stillbirth. The truth is that doctors aren't completely sure why so many babies with Turner syndrome are miscarried while others make it through pregnancy without major complications.

The most likely explanation is that there is a genetic factor in play. It could be that the majority of babies who are conceived with Turner syndrome are missing genes necessary for life, whereas those who survive have a complete set of genes, despite having only one X chromosome.

A Word From Verywell

Regardless of the explanation, if you have lost a baby with Turner syndrome to miscarriage or stillbirth, it is normal and OK to grieve. Give yourself the time and space to recovery emotionally. The odds are low of the condition recurring in a future pregnancy, but a genetic counselor should be able to give you more information about any concerns you may have if you are planning to try again.

3 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. National Center for Advancing and Translational Sciences. Turner syndrome.

  2. Bianchi DW. Turner syndrome: New insights from prenatal genomics and transcriptomics. Am J Med Genet C Semin Med Genet. 2019. doi:10.1002/ajmg.c.31675

  3. National Institutes of Health: National Library of Medicine. Turner syndrome.

By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage.