IVF does not increase risk of developmental disorders in children, but sub-fertility itself may influence neurodevelopment

Dr. Karin Middelburg, from the University Medical Center Groningen, Groningen, The Netherlands, said that the study, which looked at the quality of general movements in infants at the age of three months, showed that singleton children born after IVF were not at increased risk for abnormal general movements.

This suggests that they are not at increased risk of cerebral palsy (CP) or other neurodevelopmental disorders compared with their peers born from natural conception in sub-fertile couples who were referred to the fertility clinic for fertility evaluation or treatment, she said.

In the past, there has been concern that babies born after IVF were at risk of such disorders because of the association with preterm birth and low birth weight, so this was an important question to answer, said Dr. Middelburg. The research team investigated 68 singleton babies born after IVF/ICSI with controlled ovarian hyperstimulation (the conventional method, where the ovaries are stimulated with hormones to produce multiple oocytes (egg cells)) and 57 singletons born following IVF/ICSI in a modified natural cycle of oocyte production, where the one egg cell which develops naturally is utilised.

In this latter method, the need for hormonal medication is much reduced, although minimal hormonal support is still necessary in order to prevent spontaneous ovulation. Ninety singleton babies born to sub-fertile parents who conceived naturally during fertility evaluation or while on the waiting list for treatment were used as a control group.

The researchers studied the babies’ neurodevelopment by assessing their spontaneous movements, known as general movements, early in infancy. “The quality of these movements reflects the integrity of the young brain and is related to developmental disorders such as CP, minor neurological dysfunction, and behavioural problems when children reach school age,” said Dr. Middelburg.

Data on quality of movements in the general population was also available by assessing 450 singleton children at child welfare clinics. The researchers found that the quality of general movements of singletons born following conventional IVF and IVF using the modified natural cycle were similar to that of the singletons born to sub-fertile couples.

“However, we were intrigued to find that sub-fertility appeared to relate to less-than-optimal neurological condition in early infancy,” said Dr. Middelburg. “Mildly abnormal general movements occurred more frequently in the children born to sub-fertile parents than in the general population, and this suggests that factors relating to sub-fertility rather than to IVF procedures come into play.”

The children in the study are currently being assessed a number of times until their second birthday. The team intends to follow up the work by recalling them for further assessment around their fourth birthday. “Some developmental disorders, such as cognitive and behavioural problems are only fully detectable when children grow older,” said Dr. Middelburg. “This study is important, not only because it informs us about the effect of hormonal stimulation on brain development, but also because we believe that many factors associated with sub-fertility may be implicated in the neurological condition of the resulting children. This is an intriguing finding that deserves further investigation.”