>You get error because the transaction is not committed yet and the new field is not in the table. Try this:
>

>IF NOT EXISTS(SELECT column_name
>                                     FROM information_schema.columns
>                                     WHERE table_name = N'AdultInfo' and column_name = N'MaritalStatus')
>   BEGIN
>        sp_executesql N'alter table AdultInfo add MaritalStatus char(1) null' -- Only to be in other batch
>        ALTER TABLE [dbo].[AdultInfo]  WITH CHECK ADD  CONSTRAINT [CK_AdultInfo] CHECK  (([MaritalStatus] IS NULL OR ([MaritalStatus] IN ('W','S','D','M'))))
>   END
>

Looks like I need to add EXECUTE in front of the statement.