Background Genital mycoplasmas (Ureaplasma urealyticum-Uu or Mycoplasma hominis – Mh) are low grade pathogens associated with complications of pregnancy (chorioamnionitis and preterm labour); but their role as neonatal pathogens is controversial.

Aim To identify haematological markers of vertical transmission of genital mycoplasma in premature newborn infants.

Methods A retrospective cohort study done at University of Connecticut Health Centre NICU with admissions from 2003–2010. Intubated infants in the NICU had tracheal cultures sent for genital mycoplasmas (GM) and complete blood counts within 24 hrs. of birth. Infants with GM+ve were compared with GM-ve for perinatal and neonatal variables.

Results Of the 361 infants with tracheal aspirate cultures sent for GM, 50 positive were GM+ve (See Table). Infants GM+ve had significantly higher platelet counts compared to those GM-ve (285 ± 177 vs. 196 ± 83; p = 0.007). After controlling for perinatal variables (GA ≤32 wk., premature rupture of membranes, delivery mode, prenatal antibiotics and prenatal steroid) in GM+ve the adjusted odds ratio for an initial platelet count of > 250,000 was 3.83 (95% CI 1.5–9.8) with p value of 0.0049. However, GM+ve infants had no significant changes in other haematological parameters such as total WBC counts, neutrophil, monocyte, lymphocyte or eosinophil counts.

Conclusions Vertical transmission of GM to the infant is manifested subtly at birth without significant changes in haematological parameters except an increase in platelet count > 250 K.

Significance Increase in platelet counts at birth may be an important marker for the effects of GM on premature newborn infants.