Chlamydia, Gonorrhea Linked to Stillbirth or Preterm Birth

Jennifer Garcia

September 06, 2013

Sexually transmitted infections such as chlamydia and gonorrhea may be associated with stillbirth and preterm birth, according to a new retrospective cohort study published online September 4 in Sexually Transmitted Infections.

Researchers analyzed data from the New South Wales (NSW) Perinatal Data Collection, which collects information on all births in NSW, and the NSW Notifiable Conditions Information Management System, which records all diagnoses of notifiable conditions, including gonorrhea and chlamydia.

Bette Liu, MD, MPH, from the University of New South Wales, Sydney, Australia, and colleagues identified women who had a first singleton birth between 1999 and 2008 with 3 outcomes evaluated separately: spontaneous preterm birth (SPTB; delivery at <37 weeks gestation), small gestational age (SGA; less than tenth centile birth weight for gestational age by infant sex), or stillbirth. Outcomes were not mutually exclusive. Women were classified as having gonorrhea or chlamydia if they had received notification of an infection more than 1 year before the estimated date of conception, within 1 year of estimated conception date, or during the pregnancy.

Among the 354,217 women identified, the researchers found that 3658 (1.0%) had been notified of a chlamydia infection before the birth, and the majority of these women (81.3%) were diagnosed before the estimated date of conception. Gonorrhea was diagnosed in 196 (0.06%) of women, with 84.7% of them diagnosed before the estimated conception date. The overall rate of SPTB was 4.1%, SGA was 12.1%, and 0.6% were stillborn.

Chlamydia was associated with a 17% increased risk for SPTB (adjusted odds ratio [aOR], 1.17; 95% confidence interval [CI], 1.01 - 1.37), and a 40% increased risk for stillbirth (aOR, 1.40; 95% CI, 1.00 - 1.96). The researchers adjusted for multiple factors, including age, socioeconomic status, Aboriginality, region of residence, country of birth, smoking, hypertension, diabetes, and late antenatal booking.

Women with gonorrhea were twice as likely to experience a SPTB (aOR, 2.50; 95% CI, 1.39 - 4.50).

In the analysis of women more likely to have been tested for chlamydia (aged < 25 years and who gave birth between 2005 and 2008), 4.6% (n = 1784) had a prior chlamydia notification. Compared with women with no notifiable infections in this group, the risk for SPTB was significantly increased (aOR, 1.46; 95% CI, 1.19 - 1.79). The timing of the chlamydia notification had no effect on outcome.

"In this study of first-time mothers having singleton births we found that a prior history of infection with either chlamydia or gonorrhea was associated with an increased risk of SPTB, a history of chlamydia was associated with stillbirth, but neither infections were associated with a SGA birth," write Dr. Liu and colleagues.

The authors acknowledge that the low incidence of gonorrhea diagnosis underpowered the associations between this infection and pregnancy outcomes. The researchers also note that despite the recommendation in 2005 for chlamydia testing in women younger than 25 years, testing in this population was still low, at less than 15%. In addition, there were no data available on the incidence of non-notifiable infections (ie, bacterial vaginosis and trichomonas vaginalis), which may also be associated with SPTB.

Funding for this study was provided by the National Health and Medical Research Council. The authors have disclosed no relevant financial relationships.

Sex Transm Infect. Published online September 4, 2013. Abstract


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