Multiple Births and Developmental Brain Damage, 5/1997 

In early 1997, the National Center for Health Statistics Public Health Service provided important information about multiple births:  

• The number of U.S. women having triplets and other multiple births has more than quadrupled in the past two decades.  

• In 1994 there were 4,594 multiple births, up from 1,034 in 1971. These data report on the occurrence of triplets or greater; similar data are not yet available on the occurrence of twins.  

• The main reason for this rise in multiple births was that more women in there thirties were having babies, and increasingly were having multiple births. Also, older mothers tend to use fertility enhancement measures which also increase the occurrence of multiple births.  

• The rate of multiple births was highest among married, college educated women, age 30 or older.  

• Babies born in multiple births tend to be smaller and premature; they are at greater risk for health problems. On average, they are half the weight of other babies at birth and arrive seven weeks earlier.

Comment:
We know that multiple births are associated with low birth weight and prematurity. Also, previous studies have told us that low birth weight and premature babies are at a substantially higher risk of having cerebral palsy. For example, there is a 400% increase in the probability of cerebral palsy in a twin birth than in a single birth. In addition, we know that irrespective of the number of babies, very young mothers and older mothers are at greater risk of having an infant with developmental brain damage.
 

Thus, the recent statistics help explain one important reason for the increased occurrence of cerebral palsy in the United States in recent years; multiple births in older women. However, we need to be careful not to over-interpret this information. Although the risk of having developmental brain damage is increased in premature and low birth weight babies, most premature babies and most multiple birth babies do not have developmental brain damage.
 

Research is now addressing the causes of developmental brain damage in this high risk population of twins, triplets, etc.: a shared placenta and its effects on fetal development; the potential for a poorly formed placenta in older women; the intra-uterine environment in multiple gestation; the effects on the premature brain of the trauma usually accompanying the process of being born.
 

There is another important factor we must remember in regard to the increased occurrence of cerebral palsy. In the past, very low birth weight babies (under 3.3 lbs) did not survive. Today, modern methods of neo-natal intensive care permit them to survive. It has been reported that the occurrence of developmental brain damage may be as high as 30% in very low birth weight babies.
 

In summary:
Most premature and most low birth weight babies do not have developmental brain damage. Most babies born as twins, triplets or more do not have developmental brain damage. Most babies born to older women do not have developmental brain damage.
 

However, all of the above babies are at a substantially greater risk of being born with developmental brain damage and account for a major proportion of new occurrences of cerebral palsy. Why? Can we take steps that would lower the occurrence of cerebral palsy in these high risk populations (Low birth weight babies? Premature babies? Twins, triplets, and greater?).
 

The research program of our Foundation is addressing these questions.
 

© UCP Research & Educational Foundation, May 1997

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