Plasma hormone levels, cervical mucus, and vaginal cytology in normal pregnancy.

Plasma oestradiol (E2), oestriol (E3), progesterone (P), human chorionic gonadotrophin (HCG) and human placental lactogen (HPL) levels, karyopyknotic index (KPI) and cervical mucus pattern were studied serially throughout pregnancy in 17 normal women. Hormonal patterns were similar to those reported by previous investigators. The P/E2 and P/E3 ratios were high in the first trimester but remained constant thereafter until term. There was no consistent change in E2, E3, and P levels and in P/E2 and P/E3 ratios in relation to onset of labour. With 2 exceptions, the cervical mucus and vaginal cytology were normal for pregnancy. The study provides a basis for a subsequent investigation into hormonal changes in threatened and recurrent abortions and the effect of treatment with HCG.