Actually many pregnant women receive multiple mercury-laden shots even to this day. That 25-50mcg of mercury, plus formaldehyde and other toxic ingredients do reach the baby in the mother's womb as well. Autism may not always show up right away but this is a factor to consider.
Also consider this: nobody has absolute proof that vaccines DON'T cause autism. Many studies favor institutional or political bias, especially as the majority of studies are funded by institutions who financially benefit from vaccines. Also, the U.S. government has settled hundreds of lawsuits over the past few decades with parents whose child became autistic or died immediately following a shot.
Another question is what causes SIDS? Again, mothers are injected with mercury-laden shots while pregnant, up to 50 mcg per shot, even though pregnant women are warned to stay away from any type of mercury including trace amounts in tuna fish.