High Rates of HIV Testing Among Pregnant Women in Ontario, Canada
December 14, 2012
The widespread availability of potent combination anti-HIV therapy (commonly called ART or HAART) has greatly reduced deaths from AIDS-related infections in Canada and other high-income countries. ART improves the health of HIV-positive people by reducing the production of HIV and allowing the immune system to begin to repair itself. The power of ART is such that researchers and doctors increasingly expect that a young adult diagnosed today who begins ART and has minimal pre-existing health conditions will have a near-normal life span. Faced with this good news, more HIV-positive women are considering having children.
An essential part of preventing mother-to-child transmission is HIV testing for women who are thinking of having a baby or who are pregnant.
Although HIV can be transmitted from mother to child (this is called vertical transmission), the risk of transmission can be reduced to less than 1% with the following steps:
- prenatal counselling and care
- taking ART during pregnancy so that viral load is as low as possible
- having intravenous AZT (zidovudine, Retrovir) during delivery of the baby
- Caesarian section for delivery (when medically necessary)
- a short course of anti-HIV medicines for the baby after birth
- use of formula rather than breastfeeding (HIV can be transmitted via breastfeeding)
- not pre-chewing food for the baby when solids are introduced. Adults who have both HIV and oral infections can inadvertently cause a small amount of blood to leak and be present in the food that they chew. This blood can contain HIV and if the pre-chewed food is fed to the infant, it could possibly transmit HIV.
Without ART, the risk of vertical transmission can be at least 26%.
In 1997, researchers in Ontario estimated that rates of HIV among pregnant women were greater than they were in the late 1980s. After consulting with stakeholders about this situation, the Ontario Ministry of Health recommended that beginning in January 1999 counselling and HIV testing be offered to pregnant women. The recommended approach to this testing was called "opt-in," which meant that HIV testing was only done if requested by a physician and where counselling and informed consent for such testing were first obtained.
Promoting the Policy
To help educate health care providers about the new testing policy, the Ontario Ministry of Health supported the following interventions that were carried out over several years:
- physicians received pamphlets, posters and new lab testing forms
- physicians who ordered lab testing for hepatitis B virus, syphilis or rubella but not HIV were sent a memo with the test results reminding them that they could also order tests for HIV
- public health units regularly received letters about the importance of prenatal HIV testing
- physician bulletins published articles encouraging doctors to offer prenatal HIV testing
- the Toronto Department of Public Health trained health care workers about HIV testing
- posters and pamphlets about HIV testing aimed at women of childbearing age were sent to doctors' offices
- a media campaign to increase awareness of HIV in pregnancy targeted to different ethno-cultural groups
Researchers at the University of Toronto, the Hospital for Sick Children in Toronto and Public Health Ontario recently collaborated to assess trends in HIV testing among pregnant women in Ontario, reviewing data collected between January 1999 and December 2010.
Overall, HIV testing among pregnant women significantly increased over the 11 years of the study, as follows:
- 1999: 40% of pregnant women were tested for HIV
- 2010: 98% of pregnant women were tested for HIV
When researchers assessed testing rates shortly after specific periods of time when certain strategies -- such as encouraging physicians to offer HIV testing to pregnant women -- were implemented, they found that such strategies subsequently resulted in greater rates of testing.
In general, HIV testing rates were lower among older women compared to younger women.
Rates of HIV testing among pregnant women in Ontario varied, with some public health units reporting rates of 92% and others 99%.
During the study period, 455 pregnant women tested positive for HIV. Of these, nearly 60% were diagnosed with HIV for the first time because of prenatal testing.
Pregnant women aged 30 to 34 years were more likely to be HIV positive than women in other age groups.
Bear in Mind
As Ontario has a universal medical insurance program, the findings from this study may be useful for other places that have a similar health insurance system, such as Australia and Western Europe.
The Ontario prenatal HIV testing program has helped to prevent many cases of vertical transmission.
The study group noted that further research is needed in Ontario (and likely the rest of Canada) to understand why some pregnant women at high risk for HIV are not tested. The group stated that it is possible that some of these women may not have received prenatal care because "they arrived in Canada shortly before delivery or for other reasons," and so they did not receive screening for HIV. Whatever the reason(s) for not being tested, such research will be important if Ontario is to keep the number of HIV-positive babies born in this province as low as possible.
We thank Robert Remis, M.D., for his research assistance, helpful discussion and expert review.
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