A new Canadian study finds that some women are having more ultrasounds then recommended.
The study published Monday online in the Canadian Medical Association Journal says nearly one in five women have four or more ultrasound exams during the second and third trimesters.
Guidelines generally recommend two ultrasound exams be performed in a pregnancy without complications - one in the first trimester and one in the second trimester to screen for fetal anomalies.
The study also says the proliferation of diagnostic imaging is a challenge for controlling health care expenses.
In Canada, the annual operational costs for diagnostic imaging total more than $2.2-billion.
The study looked at about 1.4 million pregnant women with a single delivery from 1996 to 2007 in Ontario.
The study by doctors at McMaster University and St. Michael's Hospital in Toronto used data from the Institute for Health Information.