A drug delivery system provides for controlled mixing of drugs, using at least one mixing chamber. Flow controllers guide drugs into single or multiple catheters, enabling a single lumen catheter to dispense multiple drugs, diluting a concentrated drug to provide varying drug concentration. A buffer fluid can deliver precise drug amounts or can separate drugs within a catheter. A patient's bodily fluid can serve as a diluent or buffer fluid. A drug testing/filler apparatus may be used to facilitate filling of multiple reservoirs. Bolus or continuous delivery of drug to selected distal locations can occur at independent rates. New catheter systems, hub assemblies, and uses therefore are also described. New methods for promotion of healthy pregnancy and treatment of a developing fetus are disclosed.