Is there a way to test during pregnancy to see if my child will have schizophrenia?

No. There are currently no tests known that can identify someone at risk for schizophrenia even out of the womb. However a lot of work is being done on early signs and genetic testing.
No. This suggests that it is worth paying close attention to this child's diet and GI function, we know that one of the things inhereted in mental illnes are snp's -that result in enzymes that do not efficiently digest common foods, so watch for reflux, of constipation which would be early markers of poor digestion-optimizing nutrition and GI function is essential.