Final answer:
Genital tract lacerations, potentially leading to PPH, can be caused by the stretch during vaginal birth, and are impacted by STIs such as gonorrhea and chlamydia, which can cause PID and result in scarring that makes tissues more susceptible to tearing.
Step-by-step explanation:
Risk factors for genital tract lacerations, one cause of postpartum hemorrhage (PPH), include conditions and events that increase the likelihood of tears in the genital tract during delivery. The stretching of the vaginal canal, cervix, and perineum during vaginal birth are significant.
Sexually transmitted infections (STIs) like gonorrhea and chlamydia can also be risk factors as they may cause pelvic inflammatory disease (PID), which can lead to scarring and affect the integrity of the reproductive tissues, potentially making them more susceptible to laceration. Hormonal changes during pregnancy can alter the urogenital tract microbiota, increasing the risk of sexually transmitted and other urogenital infections, which can indirectly increase the risk of lacerations as well.