Screening for fetal risk with urinary oestrogen: creatinine ratio at 34 weeks.

The urinary oestrogen:creatinine (O/C) ratio was measured in first morning specimens of 261 women at 34 weeks gestation to assess prospectively its potential in predicting fetal complications. Forty-two patients (16.1 per cent) had low O/C ratios. All three stillbirths in the series occurred in this group and the incidences of fetal growth retardation and fetal distress in labour were also significantly increased. These complications were unusual when the O/C ratio was high. The O/C ratio at 34 weeks reflected fetal well-being more accurately than clinical examination or blood pressure measurement. The mean O/C ratios of cigarette smokers non-smokers were similar, although smokers were delivered of lighter babies. Measurement of the urinary O/C ratio is simple and inexpensive. Used as a screening test at 34 weeks it appears to provide an early and fairly reliable indication of reduced placental function.