Medicine: Birthday Predicter

To prove pregnancy in its early stages, obstetricians generally use a simple urine test. In the Aschheim-Zondek test, they inject a female mouse with a urine specimen; in the Friedman test (faster and easier to read), a virgin doe rabbit gets the injection. If the patient is pregnant, hormones in the urine produce easily detectable changes in the animal’s ovaries. The Friedman test, which takes two days to complete, can spot pregnancy with 98% accuracy* ten days after the first missed period.

Last week, a University of California researcher reported that he had discovered a new blood test for pregnancy. Dr. Ernest W. Page, an obstetrics professor, claimed that his new test had three important advantages: 1) it is faster; 2) it can determine the date of conception within a five-day margin of error, thus forecasting more accurately when the baby will be born; and 3) it provides a continuous check throughout pregnancy on whether the fetus is still alive.

Page’s method involves testing for a substance called pitocinase, an enzyme found in a pregnant woman’s blood. Pitocinase neutralizes pitocin, a mysterious pituitary hormone which seems to play a part in contracting the muscles of the uterus. As pregnancy advances, the amount of pitocinase in the blood increases at an exactly predictable rate. By measuring the concentration of pitocinase, Page determines the stage of pregnancy. His measurement method: a strip of uterus from an elderly female rat is suspended in a solution containing pitocin and a patient’s blood sample. If the patient’s blood lacks pitocinase, the pitocin-stimulated uterus contracts vigorously. But if the patient is pregnant, contractions are weaker; they vary according to the amount of pitocinase present. An abortion or death of an embryo is detectable by a drop in the amount of pitocinase.

In the fourth week of pregnancy, Page’s test takes 18 hours; after 16 weeks, it takes only 15 minutes. In trials on 52 women, he says the test has thus far failed only once.

* For another pregnancy test, see BUSINESS.