Identification of fetuses likely to suffer from future neurodevelopmental problems due to placental malfunction may become possible as early as four to six weeks after conception, thanks to a new technique developed by Weizmann Institute scientists and physicians from the Tel Aviv Medical Center. Based on a simple urine analysis, the new method should markedly facilitate the prevention or mitigation of postnatal complications such as infant death or mental retardation.
Prof. Ephraim Yavin of the Institute's Neurobiology Department and Prof. Shaul Harel of the Tel Aviv Medical Center and Tel Aviv University have studied the link between "ischemic," or blood-deprived fetuses and intrauterine growth retardation (IUGR), which occurs in 3% to 10% of all pregnancies and is responsible for 33% of all low birthweight infants. IUGR -- often recognized at birth by large head circumference relative to body weight --is common among low-income populations, smokers and certain ethnic groups and families. Although up to 30% of IUGR infants "catch up" to normal children within a few years, the disorder is linked to infant and early childhood mortality, cerebral palsy, speech and learning disabilities and small body size.
IUGR often arises from circulatory problems in the expectant mother, which cause a temporary disturbance in the flow of oxygen and glucose to the developing fetal brain. If oxygen supply returns quickly enough, damage can be kept within a recoverable range; however Yavin and Harel found that partial restoration of oxygen-rich blood causes the cerebral blood elements and the placenta to produce lipid-derived hormones called protaglandins. One of them, thromboxane, acts to constrict the blood vessels -- decreasing blood supply to the brain and exacerbating the ischemic damage -- while the other, prostacyclin, serves to dilate the vessels, thereby reducing the damage. By measuring the ratio of these two compounds in blood and urine samples of a pregnant woman, it should be possible to determine the danger of her baby suffering from developmental retardation.
Currently, ischemic fetuses are identified through Doppler ultrasound measurements of blood flow from mother to fetus and from the fetal heart to the fetal brain. These measurements become reliable only after 18-20 weeks of pregnancy. It is believed that Yavin's and Harel's new method could be used as early as 4-6 weeks into pregnancy.
This research is supported by the Gulton Foundation, NY, Fidia s.p.a., Italy, and the Revson Foundation of the Israel Academy of Science and Humanities.