THE CONCENTRATION OF OESTROGENS IN THE PERIPHERAL BLOOD OF WOMEN DURING THE NORMAL MENSTRUAL CYCLE AND IN THE FIRST TRIMESTER OF PREGNANCY

Abstract

The concentration of oestrogens in maternal peripheral blood during the second and third trimesters of pregnancy has been studied by Ittrich, Jacobovitz & Igel (1960), Preedy & Aitken (1961), Roy & Mackay (1962) and Roy (1962a). The development of a more sensitive method for determining oestrogens in blood (Roy, 1962b) has made it possible to measure oestrogens in peripheral blood during the first trimester of pregnancy. Twenty millilitres of peripheral venous blood were taken from five subjects on the 5th day of the menstrual cycle and at about the time of ovulation; similar samples were taken from a group of women 6–12 weeks pregnant. Patients who later aborted were excluded. The assays were performed by the method of Roy (1962b). A Farrand fluorimeter was used for the samples from pregnant women and the more sensitive Aminco-Bowman spectrofluorimeter for samples taken during the menstrual cycle. The mean concentrations