Current scientific evidence suggests that while children conceived through Assisted Reproductive Technology (ART), such as In Vitro Fertilization (IVF), may show a slightly elevated risk of Autism Spectrum Disorder (ASD) in initial population studies, the procedure itself is not the primary cause. The association observed in large datasets is largely explained by underlying factors related to the parents’ health, the reasons for infertility, and complications that can occur during pregnancy and delivery.
Understanding the Observed Correlation
Large-scale population studies consistently show a statistical association between conception via ART, including IVF, and a minor increase in the rate of ASD diagnosis compared to those conceived naturally. Some meta-analyses suggest a 10% to 20% relative increase in the likelihood of an ASD diagnosis. However, the absolute risk remains very low.
While the rate of ASD in the general population is estimated to be between 0.6% and 1.6%, the rate for IVF-conceived children is only slightly higher, typically falling between 1.3% and 2.0%. This minimal difference points toward a correlation rather than a direct cause from the IVF process itself. For example, a large 2023 study of 1.3 million children in Canada found the incidence rate of ASD was 1.9 per 1,000 person-years in the unassisted conception group, compared to 2.7 per 1,000 person-years after fertility treatment.
When researchers adjust for known confounding factors, the association between IVF and ASD often becomes statistically insignificant or disappears entirely. This suggests that the slight elevation in risk is likely driven by characteristics shared by couples who use IVF, rather than the laboratory procedures.
Separating Patient Factors From Procedure Risk
A significant part of the observed correlation is attributed to confounding variables inherent to the patients seeking IVF, independent of the fertility treatment. The primary confounding factor is advanced parental age, as couples using ART are generally older than those conceiving spontaneously. Advanced maternal and paternal age are both independently linked to an increased risk of ASD in offspring.
For every ten-year increase in either parent’s age, the risk of ASD in the child is estimated to increase by about 20%. Paternal age is particularly relevant, as the accumulation of new genetic mutations in sperm cells over time is thought to contribute to the heightened risk. Since IVF patients are older, a portion of the observed ASD risk is simply a reflection of this age demographic, not the procedure itself.
The underlying condition of infertility, or “subfertility,” is another major factor that appears to drive the risk. Studies show that children born to parents with documented infertility who did not receive fertility treatment also have a slightly higher risk of ASD. This suggests that biological or genetic factors contributing to the difficulty in conceiving may also slightly influence neurodevelopmental outcomes. When the analysis is restricted to only infertile individuals, there is no significant difference in ASD risk between those who received IVF and those who did not.
Analyzing Specific IVF Techniques and ASD Risk
Once parental and infertility factors are accounted for, the focus shifts to whether specific components of the IVF laboratory process contribute to ASD risk. The most scrutinized technique is Intracytoplasmic Sperm Injection (ICSI), where a single sperm is injected directly into the egg, typically used for male factor infertility.
Some earlier studies found a slightly higher risk of ASD with ICSI compared to conventional IVF, potentially linked to the underlying male infertility. However, recent comprehensive studies, including a large 2023 cohort study, found no statistically significant difference in ASD risk when comparing ICSI to conventional IVF. This suggests that the increased risk previously associated with ICSI was primarily due to underlying male infertility issues, not the procedural effect itself.
Other techniques, such as extended embryo culture and cryopreservation (freezing and thawing of embryos), have also been investigated. The current consensus is that using frozen embryos does not appear to increase the risk of ASD compared to fresh embryo transfer. Robust evidence does not support a causal link between these specific steps in the ART process and a higher incidence of ASD.
Placing the Risk in Context
The most significant factors mediating the link between IVF and ASD are often related to adverse pregnancy and birth outcomes that are more common in ART pregnancies. Multiple pregnancies, which are more frequent with fertility treatments, are independently associated with an increased risk of complications like preterm birth and low birth weight. These complications, in turn, are known risk factors for neurodevelopmental disorders, including ASD.
The overall absolute increase in ASD risk for IVF-conceived children is very small. The majority of the small relative increase observed is explained by parental characteristics and pregnancy complications like multiple births and prematurity. When these factors are controlled for, the IVF procedure itself is not found to be an independent risk factor for ASD.