Mother-to-child transmission of HIV is an important but preventable mode of infection. Prevention depends on identifying pregnant women infected with HIV and offering medications during pregnancy which can dramatically decrease the chances of transmission. Currently universal screening of all pregnant women for HIV is recommended in the province of Ontario. Unfortunately the rates of screening are still low: estimates place the average rate at 50% -60%. We believe that rates in our clinic at the Women's Health Care Centre are significantly higher in part because all our patients have a first obstetrical visit. This is an unhurried visit with a trained obstetrical nurse who offers pre-test counselling and explores reasons why patients refuse testing. We hypothesize that with this system, acceptance rates for HIV screening are significantly higher than the provincial average.

We hypothesize that by having a dedicated and unhurried intake visit with a trained obstetrical nurse, pregnant women will be more likely to accept antenatal HIV testing. We further hypothesize that in our obstetrical clinic at the Women's Health Care Centre, the application of a universal opt-out screening policy will result in a testing rate that is higher than the provincial average.

This is a two part study. The first part will be a retrospective chart review while the second part will be a prospective cohort study. All antenatal patients with first visits at our clinic will be included. For the retrospective portion, 537 charts will be reviewed. For the prospective portion, 537 patients will be enrolled prospectively using a data sheet which will be included in all charts starting when the study begins. For both portions, the following information will be obtained:

• presence of HIV test
• result of test
• if test not performed, the reason documented, in any
• if testing refused, the reason for refusal

Additional information that will be obtained includes:

• number of HIV positive pregnant women cared for in our clinic during the study period
• percentage of positive cases
• difference in testing (acceptance) rates between the retrospective and prospective (when data sheet in use) portions of the study.

Inclusion Criteria:

• All pregnant women attending antenatal intake appointments at the Women's Health Care Centre at St. Michael's Hospital in Toronto, Canada between September 2003 and February 2005.

Exclusion Criteria:

• Any pregnant women obtaining antenatal care at other health care facilities.

All pregnant women attending antenatal intake appointments at the Women's Health Care Centre at St. Michael's Hospital in Toronto, Canada between September 2003 and February 2006.