Cerebral Palsy Risk Linked To Pre And Post Due Date Births Compared To 40 Week Terms

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Main Category: Pediatrics / Children's Health
Also Included In: Pregnancy / Obstetrics;  Neurology / Neuroscience
Article Date: 01 Sep 2010 - 8:00 PDT

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An examination of data conducted by Dag Moster, M.D., Ph.D., of the University of Bergen, Norway found that infants entering the world at term or later are associated with an increased risk of cerebral palsy (CP). This JAMA (Journal of the American Medical Association) published study first appeared on September 1, 2010.

CP is the most common cause of physical disability children. Non-progressive disorders of movement and posture are the key symptoms of this prevalent ailment.

Using the Medical Birth Registry of Norway's 1,682,442 births between 1967 and 2001, Moster and colleagues examined the relation of CP risk with gestational age among term and post term births that possessed no congenital anomalies. The group was followed up through 2005 by linkage to other national registries that track Norwegian lifecycles.

1,938 were identified as having cerebral palsy.

The study's authors state:

One of the strongest predictors of CP is preterm birth, with the risk of CP increasing steadily with earlier delivery. Although risk is lower among term births, about three-fourths of all infants with CP are born after 36 weeks. Within this range of term births, there are few data on the possible association of CP with gestational age.

Risk for CP was higher with earlier or later delivery, but those born at the 40 week mark showed almost zero occurrence of CP. Those born at 37 weeks had a 90% increased risk of displaying symptoms of cerebral palsy. At 38 weeks, a 30% higher risk. Forty-two weeks and after deliveries had a 40% increased risk.

Clinicians typically regard term births (37-41 weeks) as low risk, with the possibility of increased risk with post term delivery. This standard definition of term does not correspond well with the period of lowest risk for CP in this study or with the weeks when most infants are born.

Weeks 37 and 38 seem more to resemble weeks 42 and 43, both in CP risk and in the general likelihood of delivery, leaving 39 to 41 weeks as the optimum time for delivery. If the time of delivery affects CP risk, then intervention at 40 weeks might reduce CP risk, while elective delivery at 37 or 38 weeks might increase it.

If infants prone to CP are disrupted in their delivery times, the prevalence of CP would be unchanged regardless of time of delivery.

The research authors finally concluded:

Until the biological mechanisms for these patterns of risk in term and post term births are better understood, it would be hasty to assume that interventions on gestational age at delivery could reduce the occurrence of CP.

What is cerebral palsy?

Cerebral palsy is a term which encompasses a set of neurological conditions that cause physical disability in human development - they affect the brain and nervous system. The word cerebral refers to the area in the brain that is affected, while palsy means complete or partial muscle paralysis, frequently accompanied by loss of sensation and uncontrollable body movements or tremors. Cerebral means related to the brain or cerebrum.

A person with cerebral palsy will generally show symptoms during the first three years of life. A child/baby with cerebral palsy may have some of the signs and symptoms below:

• Achieves developmental milestones, such as crawling, walking, or speaking, later than his/her peers.
• Can be easily startled.
• Crawls in an unusual way.
• Favors one side of the body over the other.
• Has abnormal muscle tone - the child will slouch while sitting. Muscle tone refers to a person's automatic ability to tighten and relax muscle when required.
• Has bad coordination and balance (ataxia).
• Has bladder control problems.
• Has bowel movement control problems.
• Has difficulty feeding and sucking.
• Has hearing problems.
• Has involuntary, slow writing movements (athetosis).
• Has overdeveloped or underdeveloped muscles (has floppy or stiff movements).
• Has problems swallowing.
• Has problems with eyesight.
• Has seizures.
• Lies down in awkward positions.
• Muscles are stiff and contract abnormally (spastic paralysis).
• Range of movements are limited.

"Cerebral Palsy Among Term and Postterm Births"
Dag Moster, MD, PhD; Allen J. Wilcox, MD, PhD; Stein Emil Vollset, MD, DrPH; Trond Markestad, MD, PhD; Rolv Terje Lie, PhD
JAMA. 2010;304(9):976-982. doi:10.1001/jama.2010.1271

Written by Sy Kraft (B.A. Bachelor of Arts - Journalism - University of California, Santa Barbara or California State University, Northridge)
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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