Jim Hofferberth

Injuries During PregnancyTracking & Understandingthe Hidden EpidemicHank Weiss PhD, Associate ProfessorCenter for Injury Research and ControlUniversity of PittsburghAMCHP 2005 Conference

Leading Cause of Maternal Injury

Hank Weiss, Center for Injury Research & Control

So what have we learned in terms of the leading cause of pregnancy related injury for each of the levels of the injury pyramid?

We find that motor vehicle injuries are the leading mechanism for maternal and fetal injury death, maternal injury hospitalization, and probably maternal injury ED visits.

With this in mind, and the knowledge that several serious adverse pregnancy outcomes are of concern, lets focus on the motor vehicle part of the issue.

Pregnant women NOT wearing seatbelts 3times more likely to experience fetal deathHyde et al (ObGyn, 2003): Effect of motor vehicle crashes on birth & fetal outcomes in Utah

Traumatic Fetal DeathsBy MechanismSelected States, 1995-1997

Weiss et al , JAMA, 2001, October 17;286(15):1862-1868

Hank Weiss, Center for Injury Research & Control

This study, the first summarizing traumatic fetal mortality on a multi-state basis, showed that motor vehicle crashes accounted for 80% of the known listed causes of traumatic fetal death.

Fetal Crash Death Comparisons, 1998

Hank Weiss, Center for Injury Research & Control

I also used this data to extrapolate to the country as a whole, making some partial adjustments for missing data. Just looking at crash-related fetal deaths, one can make the interesting and provocative comparisons shown here.

In terms of frequency, the MV occupant fetal death cases far outnumber many other causes of fatal childhood injury that receive much more attention by public health practitioners. And this estimate does not include fetal loss

Why Is This Happening?

Shoulder BeltLap BeltSteering Wheel

Fetal & Birth Related Threats

Fetal deathPrematurityLow birth weightObstetric complicationsPlacental injuryUterine ruptureAmniotic ruptureTrauma-related elective and therapeutic abortion

Hank Weiss, Center for Injury Research & Control

For example, birth related threats include:

Fetal death Prematurity and low birth weightAnd obstetric complications such as:Placental injuryUterine ruptureAmniotic ruptureTrauma-related elective and therapeutic abortion

Threats to the Baby

Neonatal deathDirect and indirect neural and other organ and structural damageMental retardation?ADHD?Autism?Cerebral palsy?Epilepsy????

Hank Weiss, Center for Injury Research & Control

And continuing with threats to the baby, adverse outcomes can include:

Neonatal death,plus a diverse set of unquantified impacts due to direct and indirect neural and other organ and structural damage.

Risk of Fetal DeathWith Lap & Shoulder BeltResearch Projections based on Computer Modeling

16 mph26%22 mph51%28 mph76%34 mph90%

Pregnant women not wearing a seatbelt 3times more likely to experience fetal deathHyde et al (ObGyn, 2003): Effect of motor vehicle crashes on birth & fetal outcomes in Utah

For The SolutionWe Dig Deeper

Load Distribution

Confidential

Confidential

Confidential

Confidential

Fetal Crash Death Comparisons, 1998

Hank Weiss, Center for Injury Research & Control

I also used this data to extrapolate to the country as a whole, making some partial adjustments for missing data. Just looking at crash-related fetal deaths, one can make the interesting and provocative comparisons shown here.

In terms of frequency, the MV occupant fetal death cases far outnumber many other causes of fatal childhood injury that receive much more attention by public health practitioners. And this estimate does not include fetal loss

Tummy TubConfidential

*Hi. My name is Jim Hofferberth*Several years ago, A team of epidemiologists completed several extensive studies of Injury During Pregnancy. The work was not easy, because normally there is no record of fetal death.However, by examining individual case records, they learned some very interesting and frightening things. *For example they learned that the leading cause of death to both the Mom and the baby is motor vehicle crashes. Accidents also cause the most hospitalizations and emergency department visits by pregnant women.*They also learned that pregnant women who failed to buckle-up were nearly three times more likely to experience a fetal death compared to women who wore their seatbelts.

So the most important thing you can do to protect both yourself and your baby is to buckle up when youre in a car.*Nevertheless, in spite of the fact that most Moms use their seat belts today, accidents are the leading cause of traumatic fetal death. In fact 82% of all traumatic fetal deaths are caused by crashes.*In a case by case study of the narratives discussions in the death registers of several states, they were able to identify most fetal deaths, which are not normally recorded in the statistical records. In this sample they found between 350 and 700 fetal deaths in crashes, compared, for example, 125 infant crash deaths to infants during their first year of life.Its important to note that they were only able to look at the second half of the gestation period. What happened in the first 20 weeks is unknown.But the fetus is at least 5 times more likely to die in an accident than his 0 to 1 year old sibling *Why is this happening? There are several reasons. One is that mot of the infants are using infant seats, and many of them are in the back seat of the car.However, it also reflects the fact that a fetus is much more delicate than an infant, and the pregnant Mom is typically driving or riding in the front seat of the car with her lap and shoulder belt on.The lap and shoulder belt system is designed to protect the Mom, and it is not at all well configured to protect the fetus.*Here is an illustration that is used by the National Highway Traffic Safety Administration to demonstrate the correct use of the lap and shoulder belt by a pregnant woman.Youll note that the lap belt lies on top of the legs, and the shoulder belt goes just above the abdomen.*Here is a picture of a 38 week fetus. You can see that the baby has dropped. Its head is below the top of the Moms legs where the lap belt crosses. In a crash the Mom moves forward on the seat, and the lap belt pulls back, right into the babies spine.In addition, the shoulder belt passes just over the abdomen. In the third trimester of a pregnancy, the umbilical cord is usually attached to the top posterior area of the uterus. As the Mom bends forward over the lap belt, the shoulder belt pulls into the top area of the uterus near the umbilical attachment.Umbilical abruption is the primary cause of traumatic fetal death. *So its not hard to understand why the fetus is at such high risk in an accident.And its not just fetal death. There are a whole list of problems besides death of the fetus.*And it doesnt end with the birth of a baby that has survived an accident. There is another long list of complications that can and do often affect the child, including neonatal death.*If we look at the likelihood of fetal death as a function of crash speed, we see that in a 16 MPH crash, there is a o in four chance of losing the baby.At 30 MPH, fetal death is the expected outcome.*Please remember, pregnant women who failed to buckle-up were nearly three times more likely to lost their baby in a crash. So in spite of the problems of the lap and shoulder belt for the fetus, both you and the baby are much better off is you use the restraints.But we are left with a paradox. Why cant we protect the fetus as well as the Mom? *The answer is that we can, but we have to look a bit deeper to find to solution.*This is very important. The effectiveness of a restraint system is primarily determined by how well it distributes the crash forces over the body.If we look at the results of a great many crash test with various test subjects, we see solid confirmation of this effect.Here we see that a lap and shoulder belt causes fatal injuries at slightly over 30 gs. This system provides a very limited area of load application on the body.With a 5-point military aviation harness, that includes a crotch strap, live volunteers have survived 38 g crashes, although they were severely injured. This system provides a much better distribution of crash forces than a lap and shoulder belt. And the crotch strap prevents submarining of the pelvis under the lap belt.With air bag restraints, we have repeated exposures of live subjects to 40+ crashes without injury. These systems provide a very good distribution of Crash forces over the body, and we have not yet found and injury limit with this type of restraint.We also have human volunteer tests with a contoured shell in excess of 80 gs. Such a shell provides a near optimal distribution of crash forces over the entire body.

*Now think about what the most important, most vital, human organs are. Most people would say the brain, heart and lungs are the most important. Severe damage to any of these organs can cause almost immediate death.The body provides a high level of protection to all three of these organs. The brain is housed in a rigid protective fortress called the skull, When the head is impacted by any object, the resulting forces are transmitted to the brain by the skull, which provides an even distribution, or dispersion, of the forces on the brain. It is possible to concuss the brain without penetrating or breaking the skull, but its not easy.The heart and lungs are protected by the ribs. Although the ribs do not provide a continuous protective shell like the skull does, it does a pretty good job of distributing the loads caused by most objects that impact the upper thorax. The exceptions are pointed objects that can penetrate between the ribs. Even when the ribs crack, they still provide substantial protection to the heart and lungs unless the ribs completely collapse, which is often referred to as flail-chest.But look at the area where the fetus would be located. There is no bony structure at all to protect the front of the abdomen. Almost anything tat impacts or penetrates the abdomen can cause extreme distortion or penetration of the abdominal organs, including the uterus.*Now, we cant put the pregnant Mom in a complete body shell. She has to be able to move around to drive the car or take care of the older children o the way to the hospital.But we can put to fetus I a body shell, that also protects the Moms abdomen from the belts.This provides the best protection we know how to provide for the fetus, and it provides a greatly enhanced level of protection to the Mom.You can see such a shell covering the entire abdomen here in the right picture.*This is what such a shell would look like in a car. The lap and shoulder belts go over the shell, and are prevented from impinging in the abdomen in any way.The crash forces are directed away from the abdomen to the Moms pelvis and ribs, and the uterus is retained in the protective pouch of the shell throughout the event. It is also protected from the steering wheel, and other objects that often do impact the abdomen in a crash.*Heres a frontal view of the shell.*And here is a rear view.*Protection is provided by the combined action of a pelvic yoke and crotch post to prevent submarining of the pelvis under the lap belt and direct to belt forces away from the abdomen to the Moms pelvis.The abdominal bridge shell carries residual belt forces over the abdomen between the pelvis and the rib cage, and the shoulder belt forces are reacted into the lower ribs by a breast plate that provides a very even distribution of the forces to the Moms upper body.*Remember that without such a system, the fetus is at least 5 times greater risk of death on the trip to the hospital as his 0 to 1 year old brother or sister, and it is only with a supplementary restraint system designed to protect the fetus that this situation can be changed.

*We call it the Tummy Tub.