Interpregnancy Interval and Risk of Autism Spectrum Disorders
Ousseny Zerbo1, Cathleen Yoshida2, Erica P Gunderson2
1Division of Research, Kaiser Permanente Northern California, Oakland, California; and ousseny.x.zerbo@kp.org.
Insights
Short or long interpregnancy intervals (IPIs) increase autism spectrum disorder (ASD) risk. Children born less than two years or more than six years apart face a higher risk of ASD development.
Area of Science:
- Reproductive health
- Pediatric neurology
- Epidemiology
Background:
- Interpregnancy intervals (IPIs) are crucial factors in maternal and child health outcomes.
- Previous research suggests potential links between IPIs and various adverse pregnancy and birth outcomes.
- The association between IPIs and the risk of autism spectrum disorder (ASD) requires further investigation.
Purpose of the Study:
- To investigate the association between short (<12 months) and long (≥72 months) interpregnancy intervals (IPIs) and the risk of autism spectrum disorder (ASD) in subsequent births.
- To quantify the risk of ASD associated with different IPI lengths.
Main Methods:
- A cohort study of 45,261 children born between 2000 and 2009 at Kaiser Permanente Northern California (KPNC) was conducted.
- Children with ASD were identified using International Classification of Diseases, Revision 9 diagnostic codes.
- Survival analysis and logistic regression models were employed to assess the association between IPI and ASD risk, adjusting for potential confounders.
Main Results:
- Children born after an IPI of <12 months or ≥72 months demonstrated a 2- to 3-fold increased risk of ASD compared to those with an IPI of 36 to 47 months.
- Specific adjusted hazard ratios indicated elevated risks for intervals <6 months (3.0), 6-8 months (2.1), 9-11 months (1.9), 12-23 months (1.5), and ≥72 months (2.4).
- These associations remained significant after accounting for maternal BMI, parental age, and medication use.
Conclusions:
- Interpregnancy intervals of less than 2 years or greater than 6 years may be associated with an increased risk of autism spectrum disorder (ASD) in children.
- The underlying biological or environmental mechanisms driving this association are currently unknown and warrant further research.
- These findings highlight the importance of considering IPI in the context of neurodevelopmental outcomes.
Objective:
To determine whether subsequent births after short and long interpregnancy intervals (IPIs) are associated with risk of autism spectrum disorder (ASD).
Method:
We assessed the association between IPI and ASD risk in a cohort of 45 261 children born at Kaiser Permanente Northern California (KPNC) between 2000 and 2009. Children with ASD were identified from International Classification of Diseases, Revision 9 diagnostic codes 299.0, 299.8, and 299.9 recorded in KPNC electronic medical records. IPI was defined as the time from the birth of the first child to the conception of the second child. Survival analysis and logistic regression models were used to evaluate the association between IPI and risk of ASD in second-born children.
Results:
Children born after an IPI of <12 months or ≥72 months had a 2- to 3-fold increased ASD risk compared with children born after an interval of 36 to 47 months. Respective adjusted hazard ratios (95% confidence intervals) were as follows: <6 months, 3.0 (1.9-4.7); 6 to 8 months, 2.1 (1.4-3.3); 9 to 11 months, 1.9 (1.3-2.1); 12 to 23 months, 1.5 (1.1-2.1); and ≥72 months, 2.4 (1.5-3.7). The results are not explained by maternal BMI or change in BMI between pregnancies or by parental age, maternal antidepressant medication use, or unfavorable events occurring during the first or second pregnancy.
Conclusions:
Children born after interpregnancy intervals <2 years or >6 years may be at increased risk of ASD. The mechanism explaining this association is unknown, and more research is needed.
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