Current use of prenatal ultrasounds in women with singleton pregnancies is 55% greater than in 1996, even in low-risk pregnancies. More than one-third (37%) of pregnant women now receive 3 or more ultrasound tests in the second and third trimesters of a given pregnancy, found an article http://www.cmaj.ca/embargo/cmaj090979.pdf in CMAJ (Canadian Medical Association Journal) www.cmaj.ca. The increase in the use of multiple ultrasound scans per pregnancy has been more pronounced in low-risk than high-risk pregnancies, suggesting a need to review current practices.
Current guidelines recommend two ultrasounds in an uncomplicated pregnancy - one in the first trimester and one in the second to screen for fetal and genetic anomalies.
The study included almost 1.4 million singleton pregnancies between 1996 and 2006 in Ontario, Canada's most populous province. It included both low-risk and high-risk pregnancies, the latter defined by the presence of a maternal comorbidity, need for genetics counselling or a prior complicated pregnancy. The study accounted for the recent introduction of first trimester nuchal translucency scanning.
The authors found that almost 1 in 5 of all pregnant women - including those at low-risk of complications - now receive 4 or more ultrasounds in the second and third trimesters.
"Our findings are consistent with a growing body of evidence suggesting that some health interventions most beneficial to high-risk individuals are frequently directed at apparently low-risk populations," write Dr. John You of McMaster University and coauthors.