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Children
conceived through in vitro fertilization have an increased
incidence of neurologic problems that include a nearly quadrupled
risk of cerebral palsy, Swedish researchers reported in
the February 9 issue of the Lancet. Bo Strömberg,
MD, who led the investigation, told Neurology Reviews
that although most in vitro fertilization children are born
healthy, such children are at higher risk for a number of
neurologic abnormalities.
“Cerebral palsy was significantly increased in all [groups of] in vitro fertilization children compared to matched controls,” observed Dr. Strömberg. According to the study, children born after in vitro fertilization had a 3.7-times increased risk for cerebral palsy over non–in vitro fertilization controls. Risk was elevated in singleton in vitro fertilization children, who were 2.8 times as likely to develop cerebral palsy as were non–in vitro fertilization singletons. The most common types of cerebral palsy were spastic diplegia (44%), spastic hemiplegia (40%), and spastic tetraplegia (10%). Dr. Strömberg is a pediatric neurologist in the Department of Women and Child Health at University Children’s Hospital in Uppsala, Sweden.
MANY NEUROLOGIC RISKS
The Swedish population–based, retrospective, cohort study compared neurologic problems in 5,680 children born after in vitro fertilization to those in 11,360 matched controls. In addition, 2,060 twins born after in vitro fertilization were matched to a corresponding control set of 4,120 twins not conceived through in vitro fertilization. The study enrolled children who were at least 18 months old and included children up to 14 years old.
Each in vitro fertilization child was matched to two population-based controls stratified for sex, year of birth, and birth hospital. The children were assessed for mental retardation, infantile autism, behavioral and/or speech disorders, suspected developmental delay, cerebral palsy, congenital malformations, chromosomal aberrations, neuromuscular disorders, torticollis, brachial plexus injury, disorders of the joints, disorders of the eye, hearing loss, hydrocephalus, habitual tiptoeing, accidents, seizures, other neurologic disorders, severe visual impairment, and other disorders.
The most common neurologic diagnoses in children born after in vitro fertilization were cerebral palsy, suspected developmental delay, congenital malformation, mental retardation, chromosomal aberrations, and behavioral disorders.
A SIGNIFICANT INCREASE IN CEREBRAL PALSY RISK
Children conceived through in vitro fertilization, compared with matched controls, had an almost fourfold increase in risk for cerebral palsy. In singletons, this risk was almost tripled. Even after stratification by gestational age and birth weight, children born after in vitro fertilization still had a significant increase in risk of cerebral palsy; this risk increase was applicable as well to children with a gestational period of more than 37 weeks and a birth weight of 2,500 g or more, the researchers wrote.
Indeed, Dr. Strömberg reported, “When singletons were studied separately and compared to singletons in the control group, the risk was still significantly increased by almost three times. When in vitro fertilization twins were compared to normally conceived twins, no difference in risk of cerebral palsy was seen, indicating that twin pregnancy—and probably all multiple pregnancies—are strong risk factors for cerebral palsy.”
A NUMBER OF FACTORS
“The increased risk of cerebral palsy for singletons was strongly significant, and when we studied the effect of suspected risk factors in the regression analysis, we found that low birth weight, short gestational age, and male sex were risk factors for development of cerebral palsy. However, in vitro fertilization as such did not seem to have a significant impact. Although this is one of the largest studies done, this might be due to sample size,” Dr. Strömberg said.
The risk of suspected developmental delay was fourfold higher in children born after in vitro fertilization, Dr. Strömberg reported. The risk for in vitro fertilization singletons was lower but still double that for control singletons, although this was not statistically significant in this sample size.
Children born after in vitro fertilization also saw an increased but statistically nonsignificant risk of severe visual problems, though this, too, may be a reflection of small sample size.
NR
—Janis Kelly
Suggested Reading
Strömberg B, Dahlquist G, Ericson A, et al. Neurological sequelae in children born after in-vitro fertilisation: a population-based study. Lancet. 2002;359:461-465.
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