Many Pregnant Women Not Screened for Chlamydia and Gonorrhea, Study Finds


Many women are not screened for chlamydia and gonorrhea infection during their pregnancy, and follow-up testing is not always performed as medically recommended for those who test positive for chlamydia, according to a study published online in the American Journal of Obstetrics and Gynecology (AJOG).

The findings, based on an analysis of laboratory tests of 1.3 million pregnant women, highlight gaps between medical guidelines and clinical practice in screening for two sexually transmitted infections that pose health risks for pregnant women and their newborn babies.
Conducted by scientists at Quest Diagnostics and Rutgers University, the study is believed to be the largest nationally representative retrospective study of chlamydia and gonorrhea testing. It examined de-identified results of 1,293,423 pregnant women between 16 to 40 years of age in the United States who were tested by the company between 2005 and 2008.

Chlamydia and gonorrhea are the two most commonly reported sexually transmitted infections in the United States and infect up to 100,000 and 13,200 pregnant women, respectively, each year. Left untreated, the infections can raise health risks for pregnant women, such as early onset of labor, and for newborns, such as potentially serious eye infections and pneumonia. Once identified, the infections are easily treated with antibiotics.

During the study period, the Centers for Disease Control and Prevention (CDC) recommended chlamydia screening for all pregnant women and gonorrhea screening for all high-risk pregnant women, which includes women 24 years of age or younger. The American Congress of Obstetrics and Gynecology (ACOG) adopted similar guidelines in 2007.

Despite these national recommendations, the study found that only 59 percent and 57 percent of pregnant women were tested at least once for chlamydia and gonorrhea, respectively. Among women in the high-risk 16 to 24 year age group, only 69 percent were tested for gonorrhea.

According to CDC guidelines, women who test positive for chlamydia should be re-tested three weeks after therapy to monitor treatment effectiveness. Because of their heightened risk, the CDC recommends that women 25 years of age and younger be re-tested for chlamydia during the third trimester, even if an initial screen was negative.

Yet, only 33 percent of women who tested positive for chlamydia on an initial screen were re-tested within six weeks of being diagnosed, and 22 percent had no follow-up testing. Among women 25 years of age or younger, only one in five (19 percent) were re-tested after a negative chlamydia screen.

The study also found that among women who tested positive on an initial screen, 6 percent and 3.8 percent were positive on their last prenatal test for chlamydia and gonorrhea infection, respectively. In addition, some women had a positive result after a negative result when tested at different times during their pregnancy, a pattern suggesting they were re-infected by their partners. Prior research suggests that re-infection is associated with significant adverse health outcomes, such as pelvic inflammatory disease. 

In addition, the study found that age was strongly associated with infection risk. Sixteen percent of 16 year olds tested positive for chlamydia, the highest of any age group. The risk of infection steadily declined with age, reaching 3 percent of 26 year olds and less than 1 percent of 40 year olds.

We were alarmed to find that so many pregnant women in our very large, nationally representative study were not screened for chlamydia and gonorrhea, given the prevalence of these infections and the significant risks they pose for maternal and neonatal health if untreated, says Jay M. Lieberman, MD, medical director of infectious diseases for Quest Diagnostics. Testing for chlamydia and gonorrhea is simple and treatment is easy and highly effective, but if you do not screen these women, the infections can go undiagnosed and untreated.

Our findings provide evidence that supports current recommendations, and we hope our study encourages the medical community to examine the reasons behind the divergence of clinical practice and clinical guidelines, says Lieberman.

Titled Chlamydial and gonococcal testing during pregnancy in the United States, the study is now available online as an article in press at The study is expected to be published in the July issue of AJOG.

The primary strengths of the study were the large, ethnically diverse and nationally representative size aligned with the overall U.S. population of pregnant women and ability to track results of women re-tested during pregnancy. The study's limitations included selection bias toward patients who sought medical care and received testing, and a lack of access to clinical data to assess follow-up care, including success of treatment.

The study is the third by scientists at Quest Diagnostics on pregnant women to be peer reviewed.  Obstetrics & Gynecology published a study on gestational diabetes screening in 2011, and The Journal of Clinical Endocrinology and Metabolism published a study on hypothyroidism during pregnancy testing earlier this year. The studies are part of Quest Diagnostics Health Trends, a series of reports provided as a public service on health conditions based on the company's uniquely large repository of laboratory testing data. Visit

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