[Urinary oestriol excretion and the lecithin/sphingomyelin ratio in amniotic fluid in Bogota (2600 m) I. Normal pregnancy (author's transl)].

We have studied 22 pregnancies in order to establish normal values for the urinary oestriol excretion in Bogotá, a city 2600 metres above sea level. The study subjects were normal pregnant women attending the prenatal clinic of the Hospital San José de Bogotá, and belong to a racially mixed community of medium to low socio-economic level. In the study, new born weight was found low (mean +/- SEM 2.97 +/-0.06 kg) while placental weight was high (0.6 +/- 0.02 kg) with a high placenta/newborn ratio. Maternal hemoglobin was elevated (12.8 +/- 0.2g/100 ml) reflecting the effect of altitude. In 66 determinations, oestriol excretion was more than 4mg/24 hours from week 31 to 36 and of more than 5 mg/24 hours from week 35 to 40. The decreased excretion of oestriol most likely reflects impaired intrauterine fetal growth, and is probably related to nutrional, racial and socio-economic factors as well as to the altitude. In five normal term pregnancies studied, the lecithin/sphingomyelin ratio was of 2 or more and amniotic fluid creatinine was also elevated, indicating maturity of the pulmonary and renal enzyme systems of the fetus.