Comparison of Motor Vehicle Collision Injuries between Pregnant and Non-Pregnant Women: A Nationwide Collision Data-Based Study

Does abdominal protrusion in pregnant women affect abdominal injury severity in motor vehicle collisions? A nationwide database study

AIMS

Some pregnant women avoid vehicle driving owing to the risk of contact between their protruding abdomen and steering wheel. This study was performed to determine whether abdominal protrusion in late-term pregnant car users affects the occurrence and severity of abdominal injuries in motor vehicle collisions using a national crash database.

METHODS

The National Automotive Sampling System/Crashworthiness Data System was used to analyse maternal background, collision characteristics, outcome and Abbreviated Injury Scale (AIS) scores for the body regions of all persons involved in the collision.

RESULTS

Comparison of pregnant and non-pregnant women in the driver's seat showed no significant differences in the rate of AIS scores of ≥2 (2+) for abdominal injuries and female outcomes. Comparison of use of the driver's seat and front passenger's seat by pregnant women showed no significant difference in rate of AIS 2+ injuries or in maternal and fetal outcomes. Comparison of pregnant women with a gestational age of ≤27 and >27 weeks in the driver's seat showed no significant differences in rate of AIS 2+ injuries or in maternal and fetal outcomes.

CONCLUSIONS

Based on the data from relatively low-speed frontal collisions, obstetrician/gynaecologists should advise pregnant women that they do not need to change their preferred car seat from the driver's seat to another seat because of fear of contact between their protruding abdomen and the vehicle interior.

Comfortable Seatbelts for Pregnant Women with Twins in Japan: A Cross-Sectional Observational Study on Seatbelt Usage

Optimal seatbelt practices for pregnant women with twins at different gestational ages remain uncertain. To offer recommendations for a comfortable seatbelt system, this cross-sectional observational study explored seatbelt usage and driving habits among women with twins across various pregnancy stages through an online survey that explored driving conditions and comfortable seatbelts at different stages of pregnancy. Women who drove daily before their pregnancy with twins decreased their driving frequency as the pregnancy progressed. Correct seatbelt usage was lower and no seatbelt usage was higher among pregnant women with twins than those with singleton pregnancies. They adapted their seatbelt-wearing techniques to minimise pressure on the chest in the first and third trimesters and the abdomen from the second trimester onwards. The comfortable seatbelts were those that could alleviate belt pressure, featuring waist belts to reduce pressure, wider belts to avoid localised pressure, and shoulder belts resembling a backpack type. When wearing a seatbelt, avoiding pressure on the thorax and abdomen is key for pregnant women with twins. This study suggests that the suitability of driving for pregnant women with twins in their last trimester and the reliability of seatbelts designed for such women should be further examined and validated.

Pregnancy is associated with more severe injuries from motor vehicle crashes

OBJECTIVE

Whether pregnancy is associated with severe injuries from motor vehicle crashes (MVCs) remains unclear. This study aimed to investigate the potential relationship between pregnancy and severity of injuries from MVCs.

METHODS

We identified a total of 23,559 pregnant women victims who encountered MVCs during pregnancy as well as 94,236 age- and calendar year-at MVC matched non-pregnant women victims that are also involved in MVCs. Injury severity was assessed using the Maximum Abbreviated Injury Scale (MAIS) based on the diagnosis of medical claims after MVCs. Multinomial logistic regression models were used to estimate the odds ratio and corresponding 95 % CI of injury severity levels associated with pregnancy.

RESULTS

Pregnant women had a significantly higher risk of both severe (adjusted odds ratio, aOR = 1.79, 95 % CI = 1.54-2.08) and mild injuries (aOR = 8.63, 95 % CI = 8.21-9.07) following MVCs as compared to non-pregnant women victims. Particularly, pregnant women who were riding scooters had an increased risk of severe injury (aOR = 4.25, 95 % CI = 3.58-5.04). In addition, pregnant women who experienced MVC but without any injury were more likely to visit a clinic than non-pregnant MVC victims.

CONCLUSION

Pregnant women victims, particularly those who were riding scooters involved in MVCs suffered from a higher risk of severe injury as compared to their non-pregnant counterparts. Our findings suggest that women should consider avoiding riding a scooter and must use restrictive devices during pregnancy, which would help reduce the severity of injuries sustained following an MVC.

Fetal deaths and maternal injury in motor-vehicle crashes using NASS-CDS and CISS field data

OBJECTIVE

This study determined the risk for fetal death and maternal injury in the same sample of motor-vehicle crashes. The frequency and risk of serious injury (MAIS 3 + F) were also assessed by sex, pregnancy, seating position and crash type.

METHOD

The 2008-2015 NASS-CDS and 2017-2020 CISS are representative samples that were analyzed for the risk of fetal death and the risk of maternal injury grouped by MAIS 0-2, MAIS 3 + F and death (F) in 2000+ model year (MY) light vehicles. All electronic cases involving fetal mortality were reviewed for mechanism of injury. Separately, the 2000-2015 NASS-CDS and 2017-2020 CISS data was analyzed for the risk of serious injury for male, female and pregnant female occupants by seating position and crash type in 2000+ MY light vehicles. All calculations are made with weighted data. The significance of differences in risk was determined by the Rao-Scott chi-square test in SAS and z-test for differences in proportions.

RESULTS

There were 2,467 ± 1,407 fetal deaths in light vehicle crashes from 2008-2015 and 2016-2020 with an annual occurrence of 206/yr. The risk for fetal death was 1.25% ± 0.74% of exposed pregnant females. There were 127 ± 67 deaths of pregnant females, or 11/yr in the same sample. The fatality risk was 0.065% ± 0.035%. The difference in proportions was statistically significant (z = 46.1, p < 0.0001). Fetal deaths occurred 19.4-times more often than deaths of pregnant females. In 82.9% of the crashes with a fetal death, the pregnant female was not seriously injured (MAIS 3 + F). The most common mechanism of fetal death was a minor crash, in 80.1% of the weighted cases based on review of photos of the case vehicle and observing very minor structural damage to the vehicle. The minor crash involved either yaw of the occupant compartment with side loading of the pregnant female or her displacement into the restraint system and side interior in 71.7% of the crashes. A severe crash with intrusion at the seating position of the pregnant female occurred in only 11.5% of cases. It usually caused serious injury to the pregnant female and fetal death.

CONCLUSIONS

Fetal deaths occurred 19.4-times more often than deaths of pregnant females in a 12-year sample of motor-vehicle crashes. The most common mechanism was a minor crash that resulted in a fetal death without serious injury to the pregnant female and involved side or oblique loading of the pregnant female.

Severity of Placental Abruption in Restrained Pregnant Vehicle Drivers: Correct Seat Belt Use Confirmed by Finite Element Model Analysis

Despite wearing a seat belt, pregnant drivers often suffer from negative fetal outcomes in the event of motor accidents. In order to maintain the safety of pregnant drivers and their fetuses, we assessed the severity of placental abruption caused by motor vehicle collisions using computer simulations. We employed a validated pregnant finite element model to determine the area of placental abruption. We investigated frontal vehicle collisions with a speed of 40 km/h or less involving restrained pregnant drivers with a gestational age of 30 weeks. For a crash speed of 40 km/h, the placental abruption area was 7.0% with a correctly positioned lap belt across the lower abdomen; it was 36.3% with the belt positioned at the umbilicus. The area of placental abruption depended on collision speed, but we found that with a correctly positioned belt it likely would not lead to negative fetal outcomes. We examined the effects on placental abruptions of reconfiguring seat belt width and force limiter setting. A wider lap belt and lower force limiter setting reduced the area of placental abruption to 3.5% and 1.1%, respectively; however, they allowed more forward movement upon collision. A 2.5 kN force limiter setting may be appropriate with respect to both forward movement and reduced placental abruption area. This study confirmed the importance of correctly using seat belts for pregnant drivers. It provides valuable evidence about improving safety equipment settings.

Comparison of the Injury Mechanism between Pregnant and Non-Pregnant Women Vehicle Passengers Using Car Crash Test Dummies

This paper analyzes the kinematics and applied forces of pregnant and non-pregnant women dummies sitting in the rear seat during a frontal vehicle collision to determine differences in the features of abdominal injuries. Sled tests were conducted at 29 and 48 km/h with pregnant and non-pregnant dummies (i.e., MAMA IIB and Hybrid III). The overall kinematics of the dummy, resultant acceleration at the chest, transrational acceleration along each axis at the pelvis, and loads of the lap belt and shoulder belt were examined. The belt loads were higher for the MAMA IIB than for the Hybrid III because the MAMA IIB had a higher body mass than the Hybrid III. The differences in the lap belt loads were 1119 N at 29 km/h and 1981-2365 N at 48 km/h. Therefore, for restrained pregnant women sitting in the rear seat, stronger forces may apply to the lower abdomen during a high-velocity frontal collision. Our results suggest that for restrained pregnant women sitting in the rear seat, the severity of abdominal injuries and the risk of a negative fetal outcome depend on the collision velocity.

Common Pregnancy Complaints Can Lead to Motor Vehicle Collisions or Near-Miss Incidents

Pregnant women commonly report various health complaints during pregnancy, the occurrence of which is believed to cause human error. However, no study has examined the relationship between the occurrence of pregnancy complaints and the risk of motor vehicle collisions (MVCs). This study aimed to clarify the relationship between the frequency and severity of common pregnancy complaints and the occurrence of MVCs or near-miss incidents. We conducted a multicenter cross-sectional survey of 1000 pregnant women in Shiga Prefecture, Japan. The event group experiencing MVCs or near-miss incidents during pregnancy comprised 10.8% of respondents. The frequency of compression of the stomach or abdomen, tension and cramps in the lower abdomen, pelvic pain, irritability, depressed mood, distractedness, and hot flashes was significantly higher in the event group. The results of our multivariate logistic regression analysis revealed that tension and cramps in the lower abdomen, distractedness, and irritability were independent contributory factors to such events, with an odds ratio of 2.414, 1.849, and 1.746, respectively. Educating pregnant women to avoid driving when experiencing these symptoms would improve maternal and fetal safety.

Factors Affecting the Severity of Placental Abruption in Pregnant Vehicle Drivers: Analysis with a Novel Finite Element Model

We clarified factors affecting the severity of placental abruption in motor vehicle collisions by quantitively analyzing the area of placental abruption in a numerical simulation of an unrestrained pregnant vehicle driver at collision velocities of 3 and 6 m/s. For the simulation, we constructed a novel finite element model of a small 30-week pregnant woman, which was validated anthropometrically using computed tomography data and biomechanically using previous examinations of post-mortem human subjects. In the simulation, stress in the elements of the utero–placental interface was computed, and those elements exceeding a failure criterion were considered to be abrupted. It was found that a doubling of the collision velocity increased the area of placental abruption 10-fold, and the abruption area was approximately 20% for a collision velocity of 6 m/s, which is lower than the speed limit for general roads. This result implies that even low-speed vehicle collisions have negative maternal and fetal outcomes owing to placental abruption without a seatbelt restraint. Additionally, contact to the abdomen, 30 mm below the umbilicus, led to a larger placental abruption area than contact at the umbilicus level when the placenta was located at the uterus fundus. The results support that a reduction in the collision speed and seatbelt restraint at a suitable position are important to decrease the placental abruption area and therefore protect a pregnant woman and her fetus in a motor vehicle collision.