Most pregnant women will receive at least one ultrasound during the course of their pregnancies. Ultrasounds are not mandatory, however, and there are a number of factors a woman might want to consider before she submits to this routine exam. She should discuss these factors with her doctor or midwife.
History
Ultrasound technology was introduced in the mid 1950s by Scottish obstetrician Dr. Ian Donald, but it was not used routinely for pregnancy until the late 1970s. X-rays were the diagnostic tool of choice prior to ultrasounds, until they were found to contribute to birth defects and other illness in infants.
Ultrasound Defined
When a woman receives an ultrasound, she lies on a slightly elevated table with her shirt pulled up to her chest. The ultrasound technician places a small amount of warm jelly on her stomach to lubricate the surface and make it easier to maneuver the ultrasound wand. The machine then emits high-frequency sound waves that produce a real-time image of the uterus and its contents on a screen.
The American Congress of Obstetricians and Gynecologists, or ACOG, does not have official guidelines for when ultrasounds are routinely done in early pregnancy. Some obstetricians order them around six weeks to confirm and date the pregnancy, at nine weeks to confirm the heartbeat, at 12 weeks to test for Down's syndrome and around 20 weeks for a complete anatomical picture.
Benefits
Amniocentesis and chorionic villus sampling, or CVS, are invasive tests that can be done in early pregnancy to detect a variety of genetic defects, but both carry a slight risk of miscarriage. Ultrasound technology can also detect some of these defects, and it is much less invasive with less risk of miscarriage. Some doctors argue that ultrasound is the best way to detect intrauterine growth retardation, a serious condition that can result in fetal death.
Ultrasound is an easy way to detect multiple pregnancies, which otherwise would not be caught until much later in the pregnancy--or possibly not until birth. Early ultrasound can help accurately date a pregnancy, although if a woman was charting her temperatures and monitoring her fertility beforehand, she would likely already have a very accurate conception date.
Warning
The World Health Organization argues that there is not enough evidence to support that ultrasound truly benefits baby or mother. In fact, Midwifery Today points to several studies that show a possible link between ultrasound exposure and autism. The U.S Food and Drug Administration encourages "prudent use" of ultrasound technology and, along with the ACOG, discourages 3-D ultrasounds and fetal keepsake videos that have enjoyed a recent surge in popularity.
Considerations
A pregnant woman should consider just how important it is to her to have whatever knowledge may be obtained from an ultrasound. If she is a low-risk pregnancy, perhaps she will choose to opt out of ultrasounds. If she is high-risk, ultrasound may offer her peace of mind. Because of the high false positive rate of the ultrasound, if a defect is found, more invasive amniocentesis or CVS tests are usually ordered. Even then, the results are not always 100 percent accurate.
References
- World Health Organization: Ultrasound for Fetal Assessment in Early Pregnancy
- U.S. Food and Drug Administration: Ultrasound Imaging
- U.S. Food and Drug Administration: Radiation Emitting Products
- Midwifery Today: Ultrasound, More Harm than Good?
- Midwifery Today: Questions About Prenatal Ultrasound and the Alarming Increase of Autism
