During the last few weeks of pregnancy, doctors sometimes use ultrasounds to attempt to determine the likely birth weight of the baby. In some cases, the doctors determine that the fetus may be considerably larger than expected. This is a condition known as macrosomia. When this is suspected, doctors are much more likely to recommend c-section deliveries or other interventions which may expose the mother and the infant to increased risk of injury or death.
A recent study indicates that most of these risky interventions may be unnecessary. Researchers have determined that many of these diagnoses of macrosomia are inaccurate. The study indicates that only one third of infants that had been diagnosed macrosomic using ultrasound measurements were actually found to be macrosomic at birth. Infants who had been predicted to be macrosomic were twice as likely as others to be delivered via c-section.
The lead researcher noted that while ultrasound technology has improved extraordinarily in recent years, the accuracy of predicted birth weight determinations has not improved along with the technology. Among the pregnancies included in the study, 44 percent of weight predictions were off by more than 10 percent.
Hopefully this type of research will serve several purposes. It can act as a starting point to develop improved methods of predicting birth weight so that those babies that require intervention will receive it, and those who do not, will not be put at unnecessary risk. In the meantime, this study should help doctors weigh the risks and benefits of early intervention more accurately.
Source: Family Practice News "Ultrasound Diagnosis of Fetal Macrosomia Found Inaccurate" Susan London, Aug. 8, 2011