(Press-News.org) Doctors have known for some time that children born after fertility treatments such as in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) are at increased risk of cerebral palsy. However, it was not known whether this risk was due to the treatment itself, the higher frequency of preterm or multiple births, or a mechanism associated with couples' underlying infertility.
Now, new research published online in Europe's leading reproductive medicine journal Human Reproduction [1] today (Wednesday 3 November) indicates that underlying infertility is not the main reason for the increased risk seen in IVF/ICSI children.
The study led by Dr. Jin Liang Zhu, an epidemiologist at the Danish Epidemiology Science Centre at the University of Aarhus, Denmark, is the first to examine the association between the time it takes a couple to achieve a pregnancy and the risk of cerebral palsy. The researchers used the Danish National Birth Cohort to compare children born after 0-2 months of waiting time to pregnancy with those born after a time to pregnancy of 3-5 months, 6-12 months, and longer than 12 months, as well as those born after IVF/ICSI, ovulation induction with or without intrauterine insemination, and unplanned pregnancies. Parents who conceive quickly are likely to be normally fertile, while a waiting time of a year or more is likely to indicate some degree of subfertility.
After adjusting for factors that could influence the health of the baby, such as the mother's age, parity, whether or not she smoked, her education, the sex of the child, whether the birth was preterm, and whether it was a multiple birth (e.g. twins or triplets), the researchers found there was no significant association between the time to pregnancy and the risk of cerebral palsy in children born as a result of a spontaneous pregnancy, even after a waiting time to pregnancy of a year or more.
Dr. Zhu said: "Our research enabled us to examine whether untreated subfertility, measured by time to pregnancy, might be the reason for the higher risk of cerebral palsy after IVF/ICSI. Our results showed that this was not the case because, even for couples who took a year or longer to conceive, there was no statistically significant increased risk if they conceived spontaneously."
The researchers did find that, even after adjusting for the risks associated with preterm births and multiple pregnancies (both of which are more common during fertility treatment), children born after IVF/ICSI treatment had double the risk of cerebral palsy compared with children born after spontaneous conception. However, this was only when they were compared with children conceived spontaneously within two months – a group in which fertility treatments would never be used. When the IVF/ICSI children were compared with children conceived spontaneously after a waiting time to pregnancy of more than a year, the risk decreased.
Dr. Zhu said: "It is important to stress that the risks of cerebral palsy after IVF/ICSI are low. Out of more than 90,000 children in the Danish National Birth Cohort, born between 1997 and 2003, only 165 (0.18%) were diagnosed with cerebral palsy. Of the 3,000 children in this cohort born after IVF/ICSI, only 17 (0.57%) had cerebral palsy. This means that the absolute risk of having a child with cerebral palsy after IVF/ICSI treatment is still low – approximately one in 176 babies – and this risk is even lower if the children are born as a result of a single embryo being transferred to the mother's womb, thus avoiding the risks of a multiple pregnancy. Further analysis of the data showed that, when children born after IVF/ICSI were compared with children conceived spontaneously after a waiting time of more than 12 months, the elevated risk of cerebral palsy reduced and was no longer statistically significant."
Dr. Zhu concluded: "More research is needed into why there might be an increased risk of cerebral palsy associated with IVF/ICSI, besides the pathway of multiple pregnancies and preterm births. It is also important to remember that IVF/ICSI techniques have developed and improved considerably since 2003 when the youngest children in our study were born."
Another study [3] of a much larger group of children in Sweden (2,623,517 babies born between 1982-2007, of which 31,587 babies were born after IVF) has found no statistically significant increase in cerebral palsy in children born after IVF/ICSI, after adjusting for confounding factors. For the period 2004-2007 when the rate of multiple births fell to less than 10% in Sweden, the risk of cerebral palsy after IVF was the same as for babies conceived spontaneously. The authors concluded that any slight increase in cerebral palsy was "most likely a consequence of an increased risk of neonatal morbidity, notably associated with multiple births".
Professor Karl Nygren, one of the authors of the Swedish study and deputy co-ordinator of the European Society of Human Reproduction and Embryology's special interest group on safety and quality in ART (assisted reproduction technology) said: "It seems to us that the previously noted increased risk of cerebral palsy after IVF is certainly decreasing and may actually have disappeared in recent years in countries that only transfer a single embryo at one time. This is good news."
(###
[1] Parental infertility and cerebral palsy in children. Human Reproduction journal. doi:10.1093/humrep/deq206
[2] The work was supported by grants from the Danish Medical Research Council and the Intramural program of the National Institute of Environmental Health Sciences, National Institutes of Health in the USA.
[3] "Cerebral palsy in children born after in vitro fertilization. Is the risk decreasing?" European Journal of Paediatric Neurology, published online on May 5, 2010.
At a global scale, the sickle cell gene is most commonly found in areas with historically high levels of malaria, adding geographical support to the hypothesis that the gene, whilst potentially deadly, avoids disappearing through natural selection by providing protection against malaria.
In a study funded by the Wellcome Trust, geographers, biologists and statisticians at the University of Oxford, together with colleagues from the KEMRI-Wellcome Trust Programme in Kenya, have produced the first detailed global map showing the distribution of the sickle cell gene. The ...
INDIANAPOLIS – A model program developed at Indiana University to provide care to low-income older adults in their homes has earned recognition for its effective approach and cost-saving benefits in a leading national medical journal.
A paper published in the Nov. 3 issue of the Journal of the American Medical Association praises a team approach developed by researchers from Indiana University and the Regenstrief Institute as one of three models with the greatest potential to improve the effectiveness and efficiency of the complex primary health care of older adults.
"Health-care ...
Black raspberries are highly effective in preventing colorectal tumors in two mouse models of the disease, according to a University of Illinois at Chicago study.
The findings are published in the November issue of Cancer Prevention Research.
Colorectal cancer is the third most common cancer and the second leading cause of cancer-related death in both men and women in the U.S., according to the National Cancer Institute.
Building on previous research that found black raspberries have antioxidant, anti-cancer, anti-neurodegenerative and anti-inflammatory properties, ...
A new study analysing how complex, highly-evolved societies are organised in nature has found that it is workers that play a pivotal role in creating well-ordered societies where conflict is minimised.
For when it comes to determining who reproduces in ants, University of Leicester biologists have found the humble worker is queenmaker – it is they who choose their queen.
This information is key to understanding the evolution of complex interdependent societies - over 100 millions years old - that have evolved mechanisms ensuring stable cohabitation and conflict resolution.
What ...
A study by Yale School of Medicine researchers reveals that the illnesses and injuries that can restrict the activity of older adults or land them in the hospital are linked to worsening functional ability, especially among those who are physically frail. The report appears in JAMA's November 3 theme issue on aging.
Thomas M. Gill, M.D., the Humana Foundation Professor of internal medicine (geriatrics), investigative medicine and epidemiology and public health at Yale, will present the findings at a JAMA media briefing at the National Press Club November 2 at 10 a.m. ...
Researchers at the University of California, San Diego School of Medicine have discovered that a multi-tasking protein called FoxO1 has another important but previously unknown function: It directly interacts with macrophages, promoting an inflammatory response that can lead to insulin resistance and diabetes. Contrarily, it also generates a negative feedback loop that can limit damage from excessive inflammation.
The findings by Jerrold M. Olefsky, MD, Associate Dean for Scientific Affairs and professor of Medicine, and colleagues are published in the November 2 issue ...
Brain damage continues to develop and evolve for months after a traumatic brain injury (TBI), revealing a potential target for treatments to improve brain trauma, new research led by the University of Melbourne, Australia has found.
The study funded by the Victorian Neurotrauma Initiative is published in the latest issue of The Journal of Nuclear Medicine (JNM).
Around 400,000 Australians have a disability related to traumatic brain injury with cognitive, psychiatric and epileptic problems the most common symptoms. The major cause of TBI is motor vehicle accidents. ...
While the risk remains low the authors are surprised at the results and say "a critical evaluation of the obstetrical care system in the Netherlands is urgently required."
Despite the high level of medical care in the Netherlands, the perinatal mortality rate (death of fetus or new born baby) is one of the highest in Europe, says the study.
The management of childbirth delivery in the Netherlands is divided into two independent systems – midwife-led care for low risk pregnancies and obstetrician-led care for high-risk pregnancies. This differs to all other obstetric ...
The mysterious origins of Australia's bizarre and secretive marsupial moles have been cast in a whole new and unexpected light with the first discovery in the fossil record of one of their ancestors.
The find reveals a remarkable journey through time, place and lifestyle: living marsupial moles are blind, earless and live underground in the deserts of the Northern Territory, Western Australia and South Australia, yet their ancestors lived in lush rainforest far away in north Queensland.
In the journal Proceedings of the Royal Society B, a team led by Professor Mike ...
Researchers at the Swedish medical university Karolinska Institutet have shown that they may be able to monitor the aging process in the brain, by using MRI technique to measure the brain lactic acid levels. Their findings suggest that the lactate levels increase in advance of other aging symptoms, and therefore could be used as an indicator of aging and age-related diseases of the CNS.
"It's exciting to think that we are one step closer to understanding what happens as the brain ages, and how a change of brain metabolism may be important during the onset of age-related ...