Tackling sexually transmitted infections in pregnant women

New research aims to minimize transmission to neonates during delivery

Carmen Charlton

Sexually transmitted infections in pregnant women are completely preventable if diagnosed and treated before the woman gives birth, says a University of Alberta clinical microbiologist who is collecting data to see if universal screening for gonorrhea and chlamydia helps catch infection in neonates.

“If a pregnant woman has no symptoms of chlamydia or gonorrhea, she can unknowingly pass the infection to her baby during delivery,” said Carmen Charlton, an assistant professor with the Department of Laboratory Medicine & Pathology. “This can have serious consequences for infants and cause blindness, breathing difficulties like pneumonia, or bacteremia—where bacteria is in the neonate’s bloodstream.”

Alberta’s prenatal screening program has a 97 per cent capture rate for five different infectious disease markers, which require a blood sample: HIV, syphilis, Hepatitis B, varicella and rubella. In 2018, the Alberta Prenatal Screening Guidelines for Select Communicable Diseases was updated to include screening for chlamydia and gonorrhea—requiring a urine sample—in the first trimester for all prenatal women, with third trimester rescreening recommended for high-risk patient populations.

However, it’s not known if all women are being screened for chlamydia and gonorrhea in their first trimester, or if at-risk women are being screened in their third trimester.

“We also don’t know whether universal screening is both economically viable and effective at increasing the number of quality life years in Alberta,” noted Charlton.

Charlton explained that it’s problematic to determine who is actually high-risk.

“A woman might not disclose her sexual history to her physician, and the physician often doesn’t know the sexual history of the woman’s partner, which can cause a biased interpretation of who is at higher risk and who might be infected,” she said

By screening all women during delivery for chlamydia and gonorrhea, Charlton said she will be able to determine if a universal screening approach will improve chlamydia and gonorrhea detection rates and subsequently reduce infant transmission.

She is also looking at provincial data to determine if there are specific hospitals, doctors’ offices or areas that are not following the new guideline and screening for chlamydia and gonorrhea.

“In a big province like Alberta, it’s hard to reach everyone when new guidelines are put out,” she explains. “There will always be some areas that miss the communication, but it’s our job to find them and make sure that they’re aware.”

Educational interventions at targeted sites are something that Charlton said has previous experience in—a similar research project, aimed at increasing syphilis screening in the third trimester, was incredibly successful.

“We identified a number of sites that weren’t screening for syphilis, and by just having some conversations with key physicians, and doing some education in those areas, it resulted in increased screening rates from a baseline of 11 per cent to over 50 per cent, which is significant,” she said.

This research is particularly timely as the province’s sexually transmitted infections continue to skyrocket. Between 2017 and 2018, the province saw a 4.8 per cent increase of chlamydia—to 17,384 cases—and a 5.3 per cent increase of gonorrhea—to 5,009 cases. Upwards of 80 per cent of women infected with either gonorrhea or chlamydia may be unaware due to being asymptomatic.

“I’m very hopeful that we can similarly improve prenatal screening rates for chlamydia and gonorrhea with this project.”

Carmen Charlton, along with co-applicants Joan Robinson and Cameron Sklar, received funding for this Innovation project from supporters of the Lois Hole Hospital for Women through the Women and Children's Health Research Institute.

Lois Hole Hospital for Women