Prevalence of genital Mycoplasma in pregnancies with shortened cervix

To determine whether colonisation with genital Mycoplasma species (spp.) in patients presenting with a shortened cervix before 34th week of pregnancy is associated with preterm birth.

The collection of this retrospective study consisted of 100 pregnant women who presented to a German Tertiary Perinatal Center between 2017 and 2020 due to a shortened cervix defined as a cervical length of 25 mm or shorter measured by transvaginal ultrasound before 34 weeks of gestation. At the time of admission, gestational age ranged from 18 + 4 to 33 + 3 weeks (+ days) of pregnancy. All patients underwent urine polymerase chain reaction (PCR) for genital Mycoplasma [Ureaplasma (U.) urealyticum, U. parvum, M. hominis or M. genitalium]. Patients who were tested positive underwent a therapy with macrolides (azithromycin or clarithromycin).

37% of the patients were positive for Ureaplasma spp., whereas 5% (5 patients) were Mycoplasma spp.-positive. All the latter were simultaneously colonised with Ureaplasma spp. Ureaplasma-positive patients were significantly younger than those who were tested negative. Median maternal age at examination was 30 years (a) versus 31a (p = 0.04). There was no difference between Ureaplasma-positive and -negative patients regarding median maternal body mass index (BMI) (kg/m²) (23.4 versus 22.3, p = 0.41), cervical length at admission (mm) (15 versus 17, p = 0.17), gestational age at examination (days, d) (198 versus 197, p = 0.97) or gestational age at birth (d) (250 versus 257, p = 0.33), respectively. Comparing U. parvum-positive and U. urealyticum-positive patients, there was some weak indication that U. parvum-positive patients may get a shortening of the cervix earlier in pregnancy, as the median gestational age at examination was 196d versus 215d (p = 0.06). Regarding Mycoplasma-positive and -negative patients, there was no difference in all examined parameters.

Overall, one-third of all women in our study with a shortened cervix before 34th week of pregnancy were colonised with genital Mycoplasma spp. We were able to show that pregnant women, who were treated with antibiotics when tested positive for genital Mycoplasma, gave birth at the same gestational age as patients with a shortened cervix without detected Mycoplasma. This raises the question of whether routine testing and early antibiotic treatment should be established in prenatal care.