# A Review of Seatbelt Technologies and Their Role in Vehicle Safety
## 3 Results
### Pregnant Women Injuries  
The study in [97] evaluates the risk of injury in pregnant women, particularly the likelihood of placental abruption, using finite element analysis (FEA) models of a 30-week pregnant woman. It examines different placenta and seatbelt positions--correct placement on the iliac bones versus incorrect placement on the abdomen--during frontal crash tests at speeds of 35 km/h and 56 km/h.  
Similarly, [98] highlights the crucial role of combined seatbelt and airbag use in reducing the risk of Flail chest. It also identifies pre-existing risk factors, such as advanced age and stroke, that may increase vulnerability to severe injuries. Both studies by [97; 98] underscore the importance of vehicle restraints, including seatbelts and airbags, in mitigating injury severity during crashes, though they focus on different populations and injury mechanisms.  
A cohort study made in [99] on pregnant women revealed that driving frequency decreases as pregnancy progresses, particularly in women carrying twins. It also found that correct seatbelt use is lower among women with twins compared to those with singleton pregnancies. To improve safety and comfort, seatbelts for women with twins should alleviate pressure on the abdomen and chest. The study emphasizes the need for better education and specially designed seatbelts for this group.  
Impact shed tests were conducted in [100], using pregnant, MAMA IIB, and non-pregnant, Hybrid III dummies at speeds of 29 km/h and 48 km/h. The analysis of kinematics, acceleration, and seatbelt loads showed that the pregnant dummy experienced higher belt loads due to increased body mass. Significant differences in lap belt loads were observed at higher speeds. However, the forward movement of the pelvis was similar in both dummies, suggesting that seatbelts provide a comparable restraining effect for pregnant and non-pregnant occupants. The study also noted that for pregnant women seated in the back, high-speed frontal collisions could exert greater forces on the lower abdomen.  
Research on the side impact, on the side opposite to the occupant, finds that despite the presence of side airbags, vehicle passengers still suffer serious injuries and deaths [101]. The retrospective study was conducted on a sample of 86 passenger fatalities and 325 injured with AIS grade 2+. Factors such as age, sex, and BMI influence the severity of injuries. The study on side impact collisions with the opposite side shows that safety measures need to be improved for all passengers, not just those on the side hit. The study did not examine the presence of other occupants in the same row, which could have influenced the results.  
The cohort study in [102], conducted between 2001 and 2015, examined pregnant and non-pregnant women involved in motor vehicle crashes and their resulting injuries. The findings indicate that pregnant women generally experience less severe crashes, fewer fatalities, and milder injuries across most body regions. However, they were more likely to sustain abdominal injuries classified as AIS 2+. In contrast, non-pregnant women had a higher likelihood of AIS 2+ injuries under conditions such as rear-seat positioning, airbag deployment, multiple collisions, rollovers, left-side impact forces, and higher crash velocities. Seatbelt use and rear-impact forces, however, were identified as protective factors for non-pregnant women.  
The study in [103] evaluates the safety of different seatbelt usage methods for pregnant rear-seat passengers and suggests enhancements for the lap-and-shoulder seatbelt design. Using MAMA IIB dummies in sled tests simulating a 48 km/h frontal impact, researchers analyzed kinematic parameters. The results showed that the correct use of a conventional seatbelt provided the most effective restraint. Additionally, integrating pretensioner and force limiter systems further minimized kinematic movement and offered the best protection, reducing the risk of chest and abdominal injuries as well as adverse fetal outcomes.