Hi, welcome to the forum, Epipen delivers a measured dose of epinephrine (also known as adrenaline) using autoinjector technology, most frequently for the treatment of acute allergic reactions to avoid or treat the onset of anaphylactic shock. In certain cases it can be used to stop local bleeding.
Epinephrine is known to act on the uterus through beta 2 receptors and can cause relaxation of the uterus. At term, it can prevent the contraction and delay the labor. I suggest you to consult gynecologist for further information. Take care and regards.
I think it prolongs labour but it as cause other problems talk to you dr if you have concerns and talk about the benefits outweighing the risks