I am44wf my husband is55wm. accidentally got pregnant. how likely are we to have an autistic child? both healthy and fit. older child is not autistic?

Autism frequency: At age 44, it is possible to have some genetic abnormalities occur, but autism is not generally something that correlates with a pregnancy after 40. Consult your OB provider about an amniocentesis for what is called karyotyping of the pregnancy. This and other tests for Down's syndrome are highly recommended .

1-2% risk: The current incidence of ASD is thought to be about 1/100 births, and an increased risk with agehas been reported, but the percentages are less than 100% so the stats are still less than 2/100 or 98% of not having autism. A bigger risk is trisomy 21, and this is routinely screened for by your OB. Best wishes.