The Injuries Caused to Pregnant Women from Car Crashes and the Seat Belt Design
“Automobile crashes are the largest single cause of death for pregnant women and the leading cause of traumatic fetal injury mortality in the United States.” — US National Library of Medicine
Not surprisingly, pregnant women take great measures to make sure they take care of their unborn child. Some women become almost obsessive about eating right, exercising, getting proper sleep and avoiding harsh environments such as a smoking area. Yet they still climb into the car and drive, an activity that puts them and their unborn baby at the greatest risk for fatal injuries.
We’re not suggesting they stay home bound throughout their pregnancy. We are only suggesting they take precautions just like they do in every other area of their lives to protect their baby.
Studies have shown that only 48.7% of healthcare providers even discuss driving during pregnancy with their pregnant patients. (And only 27% of pregnant women remember the discussion afterward.) The question is, are the healthcare providers even fully aware of the dangers much less possible solutions?
We’ve read many reports and studies about driving while pregnant. An average estimate from all the studies we’ve read are that about 3,000 pregnancies are lost every year from car crashes. That’s an astounding number. Additional uncounted adverse fetal outcomes occur as well, as many children grow up disabled as a result of injuries sustained in utero (Klinich, 1998).
For those mothers-to-be who are exceedingly cautious when driving, it is important to remember that even a relatively insignificant traffic collision can result in severe trauma to an unborn child. For this reason we find it absurd that doctors and other experts so rarely discuss the topic.
Just what are the possible adverse results of and injuries caused to pregnant women from car crashes?
Fetal death is most likely to result from placental abruption, maternal shock and maternal death.
The fetal mortality rate if the mother is in shock is 80%. During hypovolemia, an emergency condition in which severe blood or fluid loss makes the heart unable to pump enough blood to the body, the mother’s body considers the fetus to be nonessential. The mother’s body will shunt blood from the uterus, extremities and other non-essential organs to maintain her core function.
The most common and most life-threatening injury caused to pregnant women during a car crash is placenta abruption. It occurs with 30%–50% of major trauma injuries. The rate of maternal death is low, but the rate of fetal death from placental abruption is high. (Friese, Wojciehoski; 2005)
Placenta abruption is when the placenta prematurely detaches from the uterine wall, which cuts off blood flow to the placenta. That’s a delicate attachment, and it doesn’t take a lot of force to detach the placenta. This is, obviously, a critical medical condition that can be fatal not only to the baby but also place the mother’s health in serious and potentially life-threatening danger. Internal bleeding, severe abdominal pain and dizziness can result from a case of placental abruption.
Of course if a mother has fatal injuries, especially if she is fatally wounded on impact, a positive outcome for the fetus is nearly impossible. This is why researchers consider it of primary importance to properly protect the mother.
“The worst thing you can do is have the mother get hurt, and the best way to protect the mother and protect the baby is to have the mother wear a seatbelt,” Kathleen DeSantis Klinich, a researcher at the University of Michigan Transportation Research Institute, told the Times of Malta in 2013.
Uterine rupture, a spontaneous tearing of the uterus, is extremely rare during pregnancy. It occurs in less than 1% of pregnant trauma cases (Pearlman, 1990). While rare, the likelihood of fetal death from such an injury is near 100%. Uterine injury is often reported as resulting from direct loading from the seat belt or to unbelted women who are directly impacted by the steering wheel or instrument panel. In some cases damage is done the opposite side of the the area impacted by the seat belt indicating a “contrecoup” type of injury mechanism. (Contrecoup is typically a head injury that occurs on the opposite side of the head as where the trauma occurred.) (Klinch et al, 1998)
What to look for
In general trauma to the fetus can be accompanied by:
- severe abdominal pain,
- urgent or painful urination,
- excessive vaginal bleeding,
- dizziness loss of consciousness,
- swelling of the mother’s face or fingers,
- chills or fever,
- severe headache,
- a change in the baby’s movement.
It is important to remember however, outward symptoms are not always evident. For instance, the wife of the creator of the Tummy Shield was in a low speed sudden stop incident — not even a crash — which left a bruise on her belly from the seat belt and no other symptoms of injury. However, months later their child was born with a head injury. The sudden stop was the only traumatic event they could link the injury to. The baby, now an adult, was left with a life-long disability.
Direct Fetal Injury
Direct fetal injury is said to occur in fewer than 10% of crashes with pregnant occupants. Head trauma is the most common direct fetal injury, as the head is the largest portion of the fetus. (Friese, Wojciehoski; 2005) Officially it is thought that head trauma results from being compressed between the maternal pelvic bones and the steering wheel or dash. Though we have seen (as in the story behind the Tummy Shield and in Taylor’s story) the fetus of pregnant women in the passenger seat who don’t hit a steering wheel or dash but rather only impacted by the seat belt can experience head trauma. In Taylor’s case, the head trauma was fatal for her baby Bailey.
Even if a fetus survives, complications arising from early emergency delivery of a premature fetus (such as low birth weight and neonatal respiratory distress syndrome) can lead to long-term negative consequences for the child.
In the event of a crash, a previously low-risk pregnancy can become high-risk and the mother-to-be will have to take even more precautions.
Download our free PDF guide: Safer Driving During Pregnancy
What is it about cars and pregnant women?
Stefan Duma, Virginia Tech’s head of biomechanical engineering and driving while pregnant researcher, said the biggest problem is the steering wheel. The larger the belly, the closer the steering wheel, and the steering wheel hits the abdomen. Knowing crash dynamics, we question whether women’s pregnancies aren’t first impacted by the seat belt locking and engaging the hip bones. It is the seat belt that is designed to keep people in their seat and from hitting the steering wheel.
The anatomy of pregnant women while seated in automotive posture poses a unique challenge to restraint designers because of difficulty positioning the lap belt and close proximity to the steering wheel and airbag module (Klinich, 1998). In a 1999 study Klinich expanded on this saying, “even with the lap belt [correctly] positioned over the bony pelvis, it crossed the pregnant uterus in the mid-sagittal plane at a level corresponding to 50-80% of the total uterus height. This potentially allows loading of the protruding soft tissues of the pregnant abdomen by the lap belt during a frontal impact.”
There have been many studies by universities, some even included input from car manufacturers. Yet there has been no great improvement or design changes to address the safety issue. In a USA Today article, Steve Rouhana, senior technical leader for safety for Ford, said, “the seat belt is the best safety device in the vehicle today, but it doesn’t mean we can’t make it better.” (Rouhana retired from this position in December of 2015.)
Why? Perhaps because at any given time there is a low demographic of people affected. Plus the crash and injury data regarding pregnant women and unborn children is drastically underreported — we talked about that here. Thus maybe the auto industry doesn’t deem the issue one of major concern.
So what pregnant women do about this?
Ideally, pregnant women would reduce their driving/riding in the car during pregnancy. Since that is not a very realistic solution for most pregnant women. You can follow our tips for safer driving while pregnant found here.
Using their seat belt scares many pregnant women or they just find them too uncomfortable. So they opt to not use seat belts late in their pregnancies. But not using a seat belt can lead to even greater injury.
One article on the web about the subject states, “I wish there was some new, groundbreaking safety device I could tell you about, but this issue is largely overlooked and until the spotlight gets placed on the safety of pregnant women behind the wheel of a car, unborn babies (and the soon-to-be-mother drivers) will continue to be put at risk for a serious injury.”
Well, there is such a device. Tummy Shield is a crash-tested maternity seat belt positioning device and is now available in the U.S. Tummy Shield may reduce the number of pregnancies lost and serious injuries during a crash.
What are your thoughts? Share your comments below.
By Amie Durocher, Creative Director at Safe Ride 4 Kids and certified CPS Tech since 2004
Copyright 2019 Safe Ride 4 Kids. All rights reserved. You may not publish, broadcast, rewrite or redistribute this material without permission. You are welcome to link to Safe Ride 4 Kids or share on social media.
We originally published this post in March 2015. We updated the article for accuracy and comprehensiveness.
See list of studies about driving during pregnancy.