Background
Although studies have shown that several different antibiotic regimens are effective in preventing peri-abortal infection, no research has compared the side effects and patient tolerability of these regimens. Insufficient evidence exists to recommend any one medication over another.  Azithromycin 500 mg, doxycycline 200 mg, and metronidazole 500 mg are recommended for use before abortion by Planned Parenthood and the National Abortion Federation.
Primary Objective: To compare side-effect profiles of different antibiotic regimens versus placebo for first-trimester surgical abortion.
Secondary Objective: The pilot substudy investigates bacterial colonization within the endometrial cavity and drug serum levels immediately after abortion. 
Methods
We are recruiting 180 women for the main study, randomizing to one of four groups: doxycycline 200 mg, azithromycin 500 mg, metronidazole 500 mg, or placebo. At 30-60 minutes before uterine aspiration, study medications are given within dark gelatin capsules to maintain blinding. Women receiving placebo are unblinded and given azithromycin or doxycycline after all study data has been collected. Participants are surveyed at baseline, immediately before and after the abortion, and in the recovery area.  Nausea and vomiting are assessed via Likert scale at each time point.