According to researchers in New South Wales, STI (sexually transmitted infection) status may be helpful in predicting pregnancy outcomes. The study, published in the journal Sexually Transmitted Infections, claims pregnant patients with a current or past diagnosis of an STI, may be at increased risk of pregnancy complications, including having a small for gestational age (SGA) infant, spontaneous preterm birth (SPTB) or stillbirth

Birth records were pulled for about 350,000 births. Past medical history for the women named in the birth records were then pulled from state records. All births took place from 1999-2008. About 1% of the women were diagnosed with chlamydia – at least once. Of these women, more than 80% received the diagnosis prior to pregnancy. Fewer women suffered gonorrhea – 0.6%. Slightly less than 85% of the gonorrhea diagnoses occurred prior to pregnancy. Researchers also noted that about 50% of women diagnosed with gonorrhea had been diagnosed with chlamydia at least once in the past. 

Pregnancy outcomes were reported as 4% SPTB, 12% SGA and 0.6% stillbirths. After contributing factors like maternal age, lifestyle habits and health conditions were taken into account researchers found a connection between some STIs and pregnancy outcomes. 

Chlamydia was associated with increased risk of stillbirth (40%) and SPTB (17%). Women with gonorrhea were two times as likely to suffer SPTB, but there was no increase in risk of SGA. There did not appear to be a connection with timing of diagnosis and increased risk of negative pregnancy outcomes. 

Unfortunately, the researchers were unable to establish a clear cause/effect relationship between STIs and negative pregnancy outcomes, but they believe medical history of STIs or current diagnosis with an infection may be a warning sign for potential problems. If risk factors are increased, doctors can monitor patients more closely, but in many cases previous medical history is established based on personal interview – not medical record. It is extremely important for all patients to give the obstetrician, and all other medical professionals, an accurate medical history, including STIs. As noted by one study author – despite the lack of cause/effect relationship, “Our results suggest that sexually transmissible infections in pregnancy and the preconception period may be important in predicting adverse obstetric outcomes.”

Source: Bette Liu, Christine L Roberts, Marilyn Clarke, Louisa Jorm, Jennifer Hunt6 James Ward. Chlamydia and gonorrhoea infections and the risk of adverse obstetric outcomes: a retrospective cohort study. Sex Transm Infect doi:10.1136/sextrans-2013-051118.