Understanding Stillbirth Through Genetic Testing
Stillbirths are uncommon, but when they occur, they take place before a pregnant woman goes into labour. A stillbirth occurs when a baby dies inside the womb at or after 20 weeks of pregnancy. It usually does not present any warning signs, making it difficult to identify that something is wrong.
What causes stillbirth?
Known causes of stillbirths include:
- Problems with placenta – Risk of stillbirth increases in a woman with preeclampsia, a condition that results in pregnancy-induced high blood pressure. This prevents nutrients and oxygen from reaching the unborn baby.
- Birth defect – A large percentage of stillbirths occur due to chromosomal disorders or other structural defects resulting from environmental or genetic disorders.
- Infection – Foetal death can occur due to bacterial infections that may go unnoticed till serious complications develop.
- Improper growth rate – Babies who do not grow at normal rates or are smaller for their gestational age are at risk of death from lack of oxygen at birth or prior to delivery.
- Other causes may include trauma, diabetes in mother, or accidents with the umbilical cord.
Testing for understanding the cause of stillbirth
For a couple that had stillbirth or a supporting caregiver helping someone through the emotional journey that follows stillbirth, there is a need to understand why it happened.
An autopsy can reveal the cause of stillbirth, but it may not be the standard protocol at all hospitals. Testing may be a personal decision and can be made after discussing with the doctor.
Upon gaining the required permission from the couple, the stillborn baby’s body is tested by a trained doctor (pathologist). Along with certain special tests, genetic testing is done to find answers to the baby’s death and also indicate the chances of a future healthy pregnancy.
Studies suggest that 15-25% of stillbirths have an underlying genetic cause, of which a majority of cases indicate malformations in the stillborn due to chromosomal abnormalities.
Chromosomal abnormality is determined by obtaining tissue sample before delivery for amniocentesis or chorionic villus sampling test.
Stillbirths due to single gene mutation can be difficult to identify morphologically, and are usually revealed through gene sequencing of foetal tissue. Gene sequencing and other molecular studies can also shed light on various polygenic factors that could have predisposed a pregnancy towards stillbirth, like an altered birth weight.
If the cause of stillbirth is found to be due to a genetic disorder, the couple may be referred to a genetic counsellor for further tests to evaluate their risks of stillbirth or genetic disorders in child in future pregnancies.
Couples commonly feel feeling guilty, angry and responsible for stillbirth. Genetic testing can help provide some answers as to why it happened. Speaking with a counsellor and/or joining a support group where parents can talk about coping with death of their baby can also prove helpful during this time.
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“Genetic factors in stillbirths,” The Lancet, Volume 378, Issue 9794, Page 878, 3 September 2011, Joe Leigh Simpson, Juan M Acuna, http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)61416-5/fulltext
“New test offers more information on genetic causes of stillbirth,” National Institutes of Health (NIH), http://www.nih.gov/news/health/dec2012/nichd-05.htm
“Stillbirth: Trying To Understand,” American Pregnancy Association, http://americanpregnancy.org/pregnancyloss/sbtryingtounderstand.html
“Understanding Stillbirth — Diagnosis and Treatment,” webMD.com, http://www.webmd.com/baby/understanding-stillbirth-treatment
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