Transmission of genital mycoplasmas from mother to neonate in women with prolonged membrane rupture.

Colonization of the neonate with genital mycoplasmas occurs during passage through a colonized birth canal or in utero via contamination of the amniotic fluid. To define further the route of transmission we obtained cultures from the maternal vagina, the amniotic fluid and the neonatal pharynx in 131 mother-baby pairs. Sixty-six percent (33 of 50) of the corresponding amniotic fluids were colonized when the vagina was colonized with Mycoplasma hominis. When the amniotic fluid contained M. hominis, 26% (9 of 34) of the neonates were colonized. Sixty percent (66 of 110) of the corresponding amniotic fluids were colonized when the vagina was colonized with Ureaplasma urealyticum. When the amniotic fluid contained U. urealyticum, 32% (22 of 69) of the neonates were colonized. No neonates were colonized with M. hominis without prior colonization of both the vagina and the amniotic fluid. We conclude that colonization of the amniotic fluid is an important intermediate step in colonization of the neonate with genital mycoplasmas.