The nurses' health study.
D001294:Attitude to Health; D004396:Coloring Agents; D003267:Contraception / Q000379:methods; D003270:Contraceptive Agents; D003273:Contraceptive Devices; D005069:Evaluation Studies as Topic; D005260:Female; D005500:Follow-Up Studies; D006197:Hair; D006801:Humans; D009726:Nurses; D012907:Smoking; D014481:United States
D004396:Coloring Agents; D003270:Contraceptive Agents