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Ultrasounds During Pregnancy – How Many and How Often?

By Tracy Hampton, PhD
Beth Israel Deaconess Medical Center correspondent


Ultrasounds are a regular part of prenatal medical care for most pregnant women, and they provide parents with their first glimpses of their developing baby. Most women need very few scans, though, and medical guidelines firmly state that ultrasounds during pregnancy should be performed only when there is a valid medical indication, not simply to create keepsake photographs or videos.

According to the American Congress of Obstetricians and Gynecologists, there have been no reports of documented negative effects on the fetus from diagnostic ultrasound procedures. But, the ACOG discourages the use of ultrasounds for nonmedical purposes because while there are no confirmed biological effects caused by scans, there's always a possibility that some could be identified in the future.

"2D ultrasounds are the safest radiological modality offered to pregnant women, but as with everything, should be used in moderation," says Dr. Monica Mendiola, a practicing physician in Women's Health at Beth Israel Deaconess HealthCare-Chelsea and an instructor in Obstetrics & Gynecology at Harvard Medical School.

Most healthy women receive two ultrasound scans during pregnancy.

"The first is, ideally, in the first trimester to confirm the due date, and the second is at 18 weeks to confirm normal anatomy and the sex of the baby," explains Dr. Mendiola. "As long as these ultrasounds are normal and mom's abdomen measures consistent with her gestation, then that is all most women need."

Dr. Mendiola notes that if there are any problems with these initial ultrasounds, or if there is a discrepancy in the fetus size along the way, a repeat ultrasound is warranted.

"Additionally, if moms have medical issues such as diabetes or hypertension," she says, "then they too get additional scans."

Above content provided by Beth Israel Deaconess Medical Center. For advice about your medical care, consult your doctor.

Posted September 2012

Contact Information

Department of Obstetrics and Gynecology
Beth Israel Deaconess Medical Center
East Campus
330 Brookline Avenue
Boston, MA 02215
617-667-0475

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