Final answer:
Methyldopa (Aldomet) is the antihypertensive medication among the given options that can lead to a positive Coombs test result in a pregnant woman due to its potential to induce autoantibody formation.
Step-by-step explanation:
The antihypertensive medication that would cause a pregnant woman to have a positive Coombs test result is Methyldopa (Aldomet). The Coombs test is used to detect antibodies that may cause hemolytic disease of the newborn (HDN). Methyldopa is known to induce autoantibody formation in some individuals which can lead to a positive direct Coombs test, potentially resulting in hemolysis. Other antihypertensive drugs listed, such as Nifedipine, Labetalol hydrochloride, and Hydralazine, are not typically associated with a positive Coombs test.