Since October is Down syndrome Awareness Month, I thought I would dig into some critical statistics in this community to understand what’s behind the numbers. Much has been said and written in the popular American press about the 90% plus termination rate when a pregnancy receives a definitive pre-natal diagnosis of Down syndrome. Diverse sources from the New York Times to politicians Sarah Palin and Rick Santorum have used this statistic.
The 92% statistic actually comes from a systematic international study (Mansfield et. al.) of 10 individual studies conducted between 1980 and 1998.[i] Its sample of 5,035 patients only included 77 U.S. individuals drawn from three U.S. studies, all of which were conducted in the 1980s. So while technically correct globally, the U.S. sample is small and the study is not contemporary. Also this study showed great variation in termination rates not only amongst countries, but also across different regions of the U.S.
So while this 92% statistic is often referenced it may not be as applicable to the current U.S. population. A more recent review of 24 available U.S. studies conducted between 1995 and 2011, show this rate ranging from 50 – 90% depending upon the sample size and geographic location, again showing great variation across different regions in the U.S.[ii] However, even taking a simple average of the range, this means the majority of U.S. pregnancies that receive a definitive diagnosis of Down syndrome are terminated.
Note also that this statistic only applies to definitive tests for Down syndrome. Historically only 2-3% of pregnant women would chose chorionic villus sampling (CVS) or amniocentesis, the only definitive tests (99% accurate) for Down syndrome. These returned results generally only in the 2nd trimester and were expensive, invasive tests with risks of miscarriage. Thus, they were only recommended for pregnant women above the age 35, the threshold age where the likelihood of Down syndrome occurring is higher (1 in ~750 for all pregnancies; 1 in ~385 for pregnant women at 35 years of age). However in 2011 inexpensive, 1st trimester non-invasive pre-natal screening (NIPS) tests became available. Now the American Congress of Obstetricians & Gynecologists (ACOG) recommends screening for all pregnant women regardless of age. Sarah Cullen from the Massachusetts Down Syndrome Congress (MDSC) reports that since the introduction of NIPS, their First Call Program has seen a 33% rise in the number of pre-natal (vs. post-natal) referrals.[iii] An increasing number of diagnoses are being delivered on a pre-natal basis and herein lies the problem….
History shows that when pre-natal tests are introduced, termination rates of pregnancies identified with the targeted anomaly increase. Down syndrome is no exception. 25 years ago when amniocentesis was the only definitive test for Down syndrome, researchers calculated that there was about a 20% abortion rate (4,474 live births vs. 5,633 projected births based on maternal age in 1989).[iv] Over the last 20 years, however, the abortion rate for pregnancies with a diagnosis of Down syndrome has skyrocketed. In 2006, ~8,000 live births of babies with Down syndrome were projected in the U.S. Yet only 3,989, babies with Down syndrome were born, implying an abortion rate of over 50%.
Now we do not know how many of the 3,989 women that had babies with Down syndrome received a post-natal diagnosis (either because they were not offered the test and were unaware that testing for Down syndrome is available, or they rejected the tests), or a pre-natal diagnosis (they received a positive pre-natal test result and made a decision to have a baby with Down syndrome). However, history repeats itself, Given that there are now four companies offering NIPS tests and even more tests for Down syndrome in development, we can only expect an even greater increase in the abortion rate. Additionally, the recently passed Affordable Care Act is recommending universal screening for Down syndrome as “preventative care”. We see bias bleed into policy here since the only way to “prevent” Down syndrome is to terminate the pregnancy.
I live in Boston where the overwhelming majority of adults identify as “Pro Choice”. I would guess that some in this majority would be disconcerted by selective abortion of a planned baby. They might consider this an act of discrimination instead of an issue pertaining to reproductive rights. As we “advance” technologically with screening tests for more and more genetic conditions, aren’t we moving towards the elimination of certain sub-groups within our population?
Both my children are in the highest risk categories for being eliminated: a boy with Down syndrome and a girl of half-Chinese ancestry. In China and some Asian ethnic populations in the U.S., genetic testing is used to select for the sex of a child, leading to abortion when tests show positive for the undesirable XX chromosome. In most of the U.S., however 3×21 (3 copies of the 21st chromosome, or Down syndrome) is riskier for the child.
I find all of this troubling on many levels. While I myself am a Christian and believe in the value of all human life, I know many non-Christian parents of children with disabilities who espouse the view that no matter what the form or intellectual capacity, every individual has something of value to offer to the world. Though I was initially devastated with my son’s diagnosis of Down syndrome, I have learned to appreciate his many gifts. He has a joie de vie and a love for life that is unparalleled – an attitude towards life we could all learn from. He has taught me that “imperfection” is part of the human condition and this is what makes us human.
Which brings me to my last point: I wonder if our human genome is attempting to evolve to a better, higher more sophisticated form? Having three copies of our 21st chromosome is one of the most common spontaneous “alterations” in our attempts at reproduction. Dr. Dennis McGuire from the Adult Down Syndrome Center at Lutheran General Hospital in Park Ridge, Illinois posed the following provocative question: “What would happen if people with Down syndrome ruled the world?[v] Below is my Top 10 Summary, excerpted from his extensive list:
- Affection, hugging and caring for others would make a big comeback
- All people would be encouraged to develop and use their gifts to help others
- People would be refreshingly honest and genuine
- People who engage in self-talk would be considered thoughtful and creative
- “The Rat Race” would not survive
- Work would be revered, no matter what kind, from doing the dishes to rocket science
- “Here and Now” (i.e. living in the present) would command a great deal more respect than it currently does
- Speed would be far less important than doing the job right
- Stopping to smell the roses would not just be a cliché
- People would not hurt the feelings of others. They also would not lie or keep secrets. Therefore there would probably be no secret service agents, spies, or terrorists
Given this, whose genome is actually more evolved?
I’d like to conclude by circling back to NIPS and what this means for us as a community. Virtually every couple that finds themselves pregnant will be offered a test for Down syndrome. This is seldom presented as optional, but it is. Instead of agreeing to be tested as part of routine pre-natal care, I challenge you to think about the purpose of such a test (and other such tests that you will no doubt encounter). Social resistance to pre-natal genetic selection is emerging. Earlier this year, North Dakota became the first state in our nation to pass a law prohibiting abortion for sex selection or genetic abnormalities such as Down syndrome.[vi] Perhaps there is a future for both my kids after all. And for the rest of us who have no immediate plans to become pregnant, I encourage you to meet with a family living with Down syndrome. You might be surprised how a short time spent could change the course of your life for the better.
[i] Mansfield et. al., “Termination rates after prenatal diagnosis of Down syndrome, spina bifida, anencephaly, Turner and Klinefelter syndromes: a systematic literature review”, European Concerted Action: DADA (Decision-making After the Diagnosis of a fetal Abnormality). Prenatal Diagnosis, 19 (1999)
[ii] Natoli et. al., “Prenatal diagnosis of Down syndrome: a systematic review of termination rates from 1995 – 2011”, Prenatal Diagnosis, 32 (2012)
[iii]In an interview with the author on October 23, 2013, Sarah Cullen reported 32 pre-natal referrals for fiscal year 2013, compared to 18 for 2011.
[iv] Egan et. al., “Demographic differences in Down syndrome live births from 1989 to 2006”, Prenatal Diagnosis, 31 (2011)
[v] McGuire, D., “If People with Down Syndrome Ruled the World”
[vi] The Prenatal Non-Discrimination Act (PREDNA) was signed into law on March 26, 2013, online link accessed October 20, 2013, http://legiscan.com/ND/bill/1305/2013