Let's start with the last question first. I do not do cervical checks as part of routine care in my midwifery practice. If a client asks me to do a check, we will discuss the risks and benefits of checking before I actually do a cervical check. In all honesty, I prefer not to check. I use external cues to assess how well labor is progressing, and those cues have served me well during my midwifery career.
What are the reasons for cervical checks anyway? Before labor begins, a provider may use a cervical check to assess how likely it is a pitocin induction will work. Sometimes providers want to know if dilation has started before labor has begun. A check when you are admitted to the hospital is done to confirm dilation is happening during labor and can also be to show insurance enough progress has occured to justify admitting you. During labor, many providers have an assumption of how quickly you should be dilating, so they check to see if your body is conforming to their assumption.
Cervical checks do not tell you how much longer until your baby is born. They tell the provider how dilated your cervix is in the moment, and potentially how your baby's head is positioned in your pelvis. A cervix can be at 4 cm dilation, and baby could be born in the next 30 minutes or less, or a cervix can be dilated to 9 cm and labor may last another 6 or more hours. Honestly, I think medical providers feel the need to check dilation because they are not staying with you in the hospital as labor progresses, so they don't have the opportunity for assessing progress by external cues.
Cervical checks do have risks. Cervical exams increase bacterial levels in the vaginal canal which might lead infection, especially after the membranes have ruptured. Even with the most scrupulous hygiene, and wearing sterile gloves for each check, that risk does not go away. There is a risk they may unintentionally rupture the amniotic sac. Cervical checks are uncomfortable and may cause stress or anxiety, which can slow your labor. Cervical checks are subjective, dilation is estimated because we can't use a measuring tape to get a precise number, and the estimation may vary between providers. I have seen this personally when the nurse estimates dilation at 7 cm, and the doctor checks within 10 minutes and estimates dilation at 5 cm. Hearing that you have gone backward after hours of labor can be disheartening to put it mildly, and can cause unneeded stress.
I like to watch and wait for the body to let my clients know when dilation is complete. Because cervical checks are uncomfortable, intrusive, have risks and don't give me big picture info, I rarely use them. As a midwife, I understand each birth has its own unique pace and rhythm and my job is to support and nurture that, not try to manage it.