In Ontario, 1 in 5 pregnancies do not receive timely first-trimester screening for syphilis, according to new research.

In a population-based retrospective cohort study of more than 550,000 pregnancies that occurred from 2018 to 2023, 8% of pregnant women were not screened at all. Among pregnancies that were screened for syphilis, 86% were screened in the first trimester, and approximately 3% were screened in the third trimester or at delivery.

Risk factors associated with being screened late included a history of injection or general illicit drug use, living in lower income neighborhoods, and living in rural areas.

The findings were published online on May 19 in CMAJ.

Gaps in Prenatal Care

Between 2014 and 2023, rates of infectious syphilis in Canada increased from 2.3 to 53.8 cases per 100,000 women aged 15-39 years. Rates of congenital syphilis increased from 0.3 to 14.5 cases per 100,000 live births.

“Since rates of infections among women and congenital cases were increasing, we wanted to understand whether people are being screened appropriately and equitably during pregnancy,” senior author Sahar Saeed, PhD, assistant professor of public health sciences at Queen’s University in Kingston, Ontario, told Medscape News Canada.

“The best time to be screened is in the first trimester of pregnancy because the rate of vertical transmission from mother to child can be minimized with adequate treatment. Repeat testing mid-gestation, at delivery, or both is also recommended for people at increased risk of syphilis infection or reinfection,” Saeed said.

The researchers used linked administrative health data from Ontario and included 551,706 pregnancies in their analysis.

Overall, 91.9% of pregnancies (n = 507,169) underwent prenatal syphilis screening. Among these pregnancies, 85.8% (n = 435,162) were screened in the first trimester, 11.5% (n = 58,154) in the second trimester, 2.1% (n = 10,724) in the third trimester, and 0.6% (n = 3129) at delivery. The researchers noted that patterns of prenatal screening varied over time.

The proportion of pregnancies without any prenatal syphilis screening declined from 10.9% (n = 11,803) in 2018 to 5.9% (n = 5913) in 2022 and to 5.5% (n = 1376) in 2023. Conversely, the proportion of first-trimester screening increased from 77% (n = 83,471) in 2018 to 80.4% (n = 80,558) in 2022 and to 81% (n = 20,427) in 2023.

Northern Ontario had the lowest uptake of first-trimester screening in the province (71.4%). “This lower rate highlights potential gaps in prenatal care in rural areas,” Saeed noted.

Being screened in the third trimester and at delivery was associated with younger age at conception (15-19 years vs 30-39 years), drug use within 3 years before conception, recent harmful alcohol use, and living in low-income neighborhoods.

Among the population with no screening were women who had been screened for syphilis 1 year before they became pregnant.

“The guidelines recommend that, even if you were screened within a year of conception, you should be getting screened again when you are pregnant because you can acquire an infection at any point, including during pregnancy. These women did not have the same risk factor profile as the women who were screened late in their pregnancy or at delivery,” said Saeed.

“The people who are not being screened in a timely manner may have limited access to healthcare. This could be for several different reasons,” she added. “It could be limited access because they are living in rural areas. It could be because they experience stigma or discrimination when they do access the healthcare system. Despite being pregnant, they are still not accessing the appropriate preventive care.”

The researchers hope that their findings will increase awareness of the importance of screening for syphilis in pregnancy in a timely manner. They also call for different approaches to catch people who may have missed routine screening.

“One of the suggestions we make in our conclusion is to use more community-based models of care so that we can go to where populations at risk may be and test people where they are. I know of one study currently underway evaluating this approach among pregnant women. We can also think about screening pregnant people when they do have access to healthcare. That could be at an emergency department visit, which may not necessarily be associated with their prenatal care. We are currently evaluating this approach,” said Saeed.

Spreading Awareness

Educating at-risk populations about the importance of screening, not only for syphilis but also for all sexually transmitted diseases in pregnancy, is key, Nitika Pant Pai, MD, PhD, professor of clinical epidemiology and infectious diseases at McGill University in Montreal, told Medscape News Canada.

“We have to do a better job of screening pregnant women, especially those from underrepresented groups, because the bigger issue here is not the test, technologies, or the treatment, because all of this is available. The bigger issue is the fact that the women are not aware they need to be screened in a timely manner when there is still a window of opportunity to treat. We need to focus on educating these populations,” Pai said.

Testing can be done in many settings, including outreach community settings, she said. Pai and her colleagues studied the use of multiplexed testing to detect multiple sexually transmitted bloodborne infections (STBBIs) in at-risk populations using an app called AideSmart!

“The app is designed for health aides or healthcare workers to use at the point of care. We were able to get good results. The app facilitated STBBI testing, arranged for pre- or post-test counseling, facilitated linkages to care, and enhanced communication between healthcare providers and patients. It was a small study in injection drug users in New Brunswick and Montreal, but the point of the screening was to sensitize people to the importance of testing, whether results are positive or negative, and to educate them,” said Pai.

The study was funded by a Canadian Institutes of Health Research Catalyst Grant (STBBI Research in Canada: Beyond HIV/AIDS and Hepatitis C). Saeed and Pai reported having no relevant financial relationships.