The New York Times (Section A, Page 1)
February 19, 1983
DETROIT — Test results released yesterday by Sinai Hospital of Detroit and the University of Michigan Medical Center show that all of Michigan's 7-month-old septuplets are genetically identical.
Doctors first tested blood samples from each of the all-female septuplets at Sinai Hospital, where the children were born in July of last year. When all the samples matched, doctors thought the results may be in error and advised the test be repeated at a different facility.
"Though the test we use is generally accurate, we figured the odds of it being wrong are better than the odds of identical septuplets," said Dr. Paul Egriso, who oversaw the tests at Sinai Hospital. The test is based on blood type groupings.
Dr. Egriso referred the family to the University of Michigan Medical Center in Ann Arbor, where they were tested again with the same results.
"If I hadn't just seen these results, I would have told you that this was impossible," said Dr. Anna Wannamauer of the University of Michigan.
If correct, the results mean that the children are essentially seven identical twins. Identical multiple births are the product of a single fertilized egg that splits into multiple parts, while each child in a fraternal set comes from a separate fertilized egg. Fraternal twins are about twice as common, and as the number of babies in a pregnancy increases, the odds that they are all identical decrease rapidly. In extremely large multiple births, babies are generally expected to be fraternal, though there may be identical "twins" in the midst of a larger pregnancy.
This was what doctors expected in the Carlsons' case. During the delivery, doctors found two placentas. Identical babies usually share a single placenta. Fraternal babies do not, though their separate placentas may fuse and look like a single one. Because there were only two placentas for the seven babies, doctors initially assumed that there had been additional placentas that fused, though they also thought some might be identical "twins" or "triplets".
"This is obviously a very unique pregnancy," said Dr. Pilirez, who oversaw the delivery of the septuplets last year. "We don't know what could lead to the spontaenous conception of seven babies in a single pregnancy. Because there were two placentas, we thought the girls might be split into two sets of identicals. We didn't believe you could get as many as seven otherwise."
Dr. Pilirez explained that the original egg likely split very early in the pregnancy, resulting in identical twins with two separate placentas. The two resulting embryos continued splitting, resulting in three babies sharing one and four sharing the other.
According to Dr. Egriso, doctors and scientists hoped that analyzing the septuplets' blood tests might provide clues as to what caused such a large number of babies in one pregnancy. Both facilities offered the test free of charge to the family in return for the opportunity to study the results.
Fertility drugs often cause multiple pregnancies, but Robin Carlson, the septuplets' mother, was not taking any such drugs. Fertility treatments are linked only to fraternal multiple births and would not be responsible for the birth of genetically identical babies.
Prior to the Carlson septuplets, the largest number of identical babies in medical history was five, with the birth of the Dionne quintuplets in 1934.
Related: See page A14 for the reaction of the septuplets' parents
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The Carlson Septuplets, characters, and stories © 1994-2006 by Jessie Mannisto.