In Reply Carbillon et al suggested that antiphospholipid antibodies (aPLs) in the mother and/or child might confound our findings from the CHARGE (Childhood Autism Risks from Genetics and Environment) case-control study published in JAMA Pediatrics that preeclampsia, particularly severe disease with placental insufficiency, was associated with autism spectrum disorder and developmental delay.1 We hypothesized a role for suboptimal placentation to explain our findings. Poor placentation resulting from defective endovascular decidual trophoblastic invasion is a central mechanism in mothers with antiphospholipid syndrome (APS).