A composition including an elastin-like polypeptide (ELP) coupled to a therapeutic agent is provided. The ELP comprises at least about 5 repeats of the amino acid sequence VPGXG. Further provided is a method of using the composition for therapeutic agent delivery during pregnancy to reduce the amount of the therapeutic agent crossing a placenta in a pregnant subject. The method includes administering to the pregnant subject an effective amount of the composition comprising the ELP coupled to the therapeutic agent.
