For many ultrasounds are just a given. Of course I’ll get ultrasounds! There are actually some potential risks when it comes to ultrasounds. And studies haven’t shown any improvement in fetal outcomes when diagnostic ultrasounds are used.
There may be a number of benefits to having an ultrasound during pregnancy. Some studies have concluded that a baby ultrasound before 14 weeks gestation is the most accurate way to predict the due date. Some studies also found that when women had an ultrasound for dating they were less likely to be induced for post-term pregnancy. Other studies have found that dating from the last menstrual period was just as accurate as dating from an ultrasound. An obvious benefit to a baby ultrasound is learning the sex of your baby.Sure, many parents prefer to wait and be surprised, but others want to know before the birth, and the ultrasound allows that. There are other ways to discover your baby’s sex, including some of the non-invasive genetic screening tests that take a sample of the mother’s blood – e.g. the MaterniT21 test. Some mothers, like myself, want a glimpse of their baby in utero as a way to connect with their child and to be sure everything is developing normally.
Risks of baby ultrasound: Safety has not been proven
There is some concern about the heat generated by ultrasound machines. An increase in tissue temperature of 1.8 – 2.7 degrees F is thought to be safe. Studies have found that ultrasound, either regular pulsed or doppler (ultrasound technology that sends a continuous wave of ultrasound rather than the pulses of a traditional ultrasound), may heat tissue above the maximum safe temperature especially in and around boney areas and especially when the wand is help in place for longer than 2-3 seconds. Additionally doppler ultrasound has been shown to cause significant heating, especially in the baby’s developing brain, which may point to continuous waves of ultrasound being more problematic than traditional ultrasound. Animal studies have found a connection between ultrasounds and adverse effects. One study found brain hemorrhages in mouse fetuses exposed to pulsed ultrasound at doses similar to those used on human babies. Another study found that adult mice who were exposed to doses similar to ultrasound had a 22 percent reduction in the rate of cell division. These mice also experienced twice the rate of cell death in small intestine. Ultrasound at diagnostic levels has been shown to produce lung damage and focal haemorrhage in a number of mammalian species.
OK, what about humans? A new study out of the University of Washington found a correlation with autistic boys who had ultrasound scans in the first trimester and the severity of their symptoms.
Other studies (from the 90’s, when the ultrasounds were 7 times weaker) showed increased risk of miscarriage or preterm birth. One study included over 9,000 pregnant women in two groups, one which received a routine ultrasound at 16-20 weeks and one group who didn’t. In the group who received an ultrasound at 16-20 weeks, there were 16 fetal death after the 16-20 week period while there were none in the group who did not receive ultrasounds.
A UK study found that healthy mothers and babies who received two or more doppler scans to check the placenta had more than 2 times the risk of perinatal death compared to babies unexposed to doppler.
Additionally, new studies from China point to ultrasounds carrying risks including Autism, ADHD, genetic damage, jaundice, childhood cancers, and allergies. Because we know that increases in maternal temperature can cause birth defects it makes sense that if ultrasound raises the mother’s body temperature, even locally, that baby may suffer from birth defects.
If ultrasounds were able to improve the outcome of babies then the potential risk may be less significant, but studies don’t show any improvement in fetal outcomes when diagnostic ultrasounds are used. One review of studies found that ultrasound does not improve neonatal outcomes when ultrasound is used for dating, second trimester organ scan, biophysical profile, and amniotic fluid assessment in high and low risk pregnancies. Another review found that there was no improvement in the APGAR score of babies when ultrasounds were used. This review also found that there were no more live, healthy births in the ultrasound group than the control group. False positives are significant in routine ultrasound scans. Such false positives can create stress in moms (which is not good for the baby) and additional ultrasounds that may interfere with parents bonding with their unborn child.Ultrasounds have not been shown to improve infant outcomes but may be increasing the rate of interventions used in pregnancies. One study found that knowledge of estimated fetal weight independently increased a woman’s risk of having a c-section, yet fetal outcomes were not improved. That means OBs may be choosing to go ahead with c-sections based on fetal size alone, even when everything else is perfectly normal.
Yes, there are cases where an ultrasound may be the right choice, but the science points to routine ultrasounds not being beneficial to a healthy pregnancy. Ultimately, you have to decide what’s right for your family and whether the benefits outweigh the risks in your case.