Is autism risk from advanced parental age independent of birth order and autism risk? 

The question of whether autism risk from advanced parental age is influenced by birth order and autism risk has been a subject of growing interest in research. While advanced parental age is known to increase the risk of autism, the role of birth order in autism risk is less clear, sparking debates about how these factors interact. 

Some studies suggest that sibling factors, such as whether a child is a firstborn or later-born, could influence the likelihood of autism, with firstborn children having a slightly higher risk. However, whether this is tied to the age of the parents or birth order itself remains uncertain. It is possible that birth order and autism risk work independently of age, or that both factors contribute in tandem, especially in families where parents are older. 

How birth order and autism risk may relate 

Here’s what current research says about birth order and autism risk in relation to advanced parental age: 

Firstborn children may face higher risk 

Some studies suggest that firstborns might have a slightly higher risk of autism, which could be related to both sibling factors and other unknown birth-related variables. 

Advanced age and birth order might interact 

Advanced parental age may amplify risks for both firstborn and later-born children, although the degree of this interaction is still under study. Parents who have children later in life might face a compounded risk due to age-related factors, regardless of birth order. 

Visit providers like Autism Detect for personal consultations to understand how birth order and autism risk interact with advanced parental age in your family planning considerations. 

For a deeper dive into the science, diagnostic nuances, and full developmental outlook, read our complete guide to Advanced Parental Age.

Hannah Smith, MSc

Author

Hannah Smith is a clinical psychologist with a Master’s in Clinical Psychology and over three years of experience in behaviour therapy, special education, and inclusive practices. She specialises in Applied Behavior Analysis (ABA), Cognitive Behavioural Therapy (CBT), and inclusive education strategies. Hannah has worked extensively with children and adults with Autism Spectrum Disorder (ASD), ADHD, Down syndrome, and intellectual disabilities, delivering evidence-based interventions to support development, mental health, and well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy. 

Dr. Rebecca Fernandez, MBBS

Reviewer

Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewer's privacy.