This study was conducted at the Women’s Health Clinic in Southcentral Foundation’s Anchorage Primary Care Center (SCF-ANPCC) from 2006 to 2010. SCF-ANPCC provides pre-paid primary healthcare to approximately 60,000 AN/ AI people living in Anchorage, Alaska and surrounding rural areas. Women eligible for care at SCF-ANPCC could enroll in the study during pregnancy, and those women who enrolled in the first or second trimester were contacted for follow-up visits in each remaining trimester of pregnancy. Advertisements were run on radio stations and in newspapers, and a recruitment table was placed in the SCFANPCC Women’s Health Clinic. All interested individuals presented at this clinic and enrolled with a research associate or administrative assistant from the study team who was trained in survey administration and confidentiality procedures. All participants signed an informed consent or assent (signed by a parent or guardian for those participants aged sixteen to eighteen), and the Alaska Area Institutional Review Board and two tribal health boards approved this study. At enrollment and each follow-up visit, women provided a saliva sample by chewing on a sterile cotton wool Salivette(Sarstedt, Newton, NC) and answered a questionnaire in English about past and active tobacco use and SHS exposure. Instructions were read to participants with an offer to read the questions aloud, though most participants chose to read questions silently themselves. All participants wrote their own responses. Women received a $20 gift card for their time.