Parents look forward to seeing their growing babies on ultrasound, but is it necessary to get one in the second trimester? Leading OB/GYNs explain the benefits and risks so you can make an informed decision.

Ultrasounds during pregnancy are very common to check on fetal growth and may also detect certain abnormalities.

OB/GYN Dr. Roseline Dauphin-Baptiste explains, "These ultrasounds are performed by OB specialists called perinatologists, [who are] trained to perform these special ultrasounds and therefore can detect malformations, growth related problems and problems developing in the uterus itself which could pose a problem for the fetus's health."

Women having healthy, uncomplicated pregnancies may still want an ultrasound to find out the baby's sex, since ultrasounds can usually show if it's a boy or girl around 20 weeks. Ultrasounds in the second (and even third) trimester may also be done to estimate due dates or baby's size. Remember, the key word is estimate. Due dates aren't always exact nor are baby's measurements in utero.

Do you need an ultrasound in the second trimester?

In general, second trimester ultrasounds are a routine part of prenatal care. Some moms prefer having their fetus's well-being monitored with a Doppler device or even the old-fashioned way with a fetoscope. (Talk to your doctor and midwife about your options.)

Dauphin-Baptiste says ultrasounds in the later part of pregnancy are also beneficial. "We gain a lot of information from not only the second trimester ultrasounds but from the late ultrasounds as well," she says.

There is the risk that something may look abnormal but all is fine when additional testing is completed.

While a second trimester ultrasound can provide a lot of good information, like most prenatal tests or procedures, it isn't always perfect. Dr. Jim Betoni, co-author of The Pregnancy Power Workbook, says the benefits of ultrasound outweigh the risks, but adds, "There is the risk that something may look abnormal but all is fine when additional testing is completed. This situation certainly adds unnecessary stress to a family."

Are second trimester ultrasounds safe?

Generally speaking, yes. Dauphin-Baptiste says, "Ultrasounds just use sound waves and are not dangerous to either the mother or her unborn baby." However, The American Pregnancy Association says the long term effects of repeated ultrasound exposures on the fetus are not fully known.

Bottom Line^ Second trimester ultrasounds can be a great tool to track the development of your baby, but should only be used when medically necessary.

Talk to your doctor or midwife and decide if an ultrasound is right for you.

More on pregnancy

Understanding prenatal test results
Second trimester development
Second trimester ultrasounds