These are some of the costume suggestions Planned Parenthood of New York City has to offer:

Dress normally. Since STDs often can’t be distinguished with the naked eye, it’ll be up to you to tell people what you are. . . .
Dress all in copper and put copper pipe cleaners on your head: you’re an IUD! . . .
Draw a calendar on your shirt and carry a bongo drum: You’re the Rhythm Method! . . .
Walk around with a bunch of babies: You’re “abstinence only” sex education

Some are particularly brilliant:

Wear all black, but then spell out the word “Damn” on your chest with bright green dental floss: You’re a Dental Dam!

and

Drape ivy over your shoulders and paint a big “F” on your shirt: You’re IVF

And classy:

Wear galoshes and carry an oar: You’re roe v wade

Others just give me the chills:

Wear all your winter gear and curl into the fetal position whenever possible: You’re a frozen embryo.