The triggers of labor to start are a complex, multi-factorial process, which involves hormonal changes, fetal maturation and physical changes in your uterus.
The main factors that trigger labor to start are rising estrogen levels, increased fetal cortisol and decreased progesterone effectiveness as well as increased oxytocin receptors.
The key physiological and biochemical causes of labor include, fetal signaling, hormonal shifts, oxytocin and prostaglandins, uterine stretch/overdistension, inflammatory changes and fetal position.
The fetus dropping lower "lightening" and placing pressure on your cervix helps to trigger contractions and labor.
Inflammatory markers, like cytokines and prostaglandins, similar to an immune response also increase to facilitate cervical remodeling or ripening of the cervix, which also triggers labor.
As the fetus grows, your uterus also stretches, which can stimulate contractions and trigger labor to start.
Your body also increases production of oxytocin, which causes contractions and prostaglandins, that help to soften and dilate your cervix.
The ratio of progesterone to estrogen also decreases, which means that progesterone's calming effect on your uterus, declines while your estrogen increases, which makes your uterus more sensitive.
And as the fetus matures, it's hypothalamic pituitary adrenal system also triggers changes in hormones, which likely releases substances that initiate labor.
Other factors that can trigger labor to start are infection, inflammation, or uterine abnormalities as well as placental changes, like the placenta may reach a point of senility or maturity, which reduces it's output of inhibiting hormones, which can trigger labor to start.
You can tell if labor is a few days way by the signs and symptoms, which include increased vaginal discharge or losing your mucus plug "bloody show", having persistent back pain, loose stools and or diarrhea, intense Braxton Hicks contractions and a nesting instinct.
When labor is a few days away, the baby will often drop lower into your pelvis and your joints may also feel looser.
The Mucus plug and blood show during labor refers to a thick, jelly like discharge that is sometimes tinged with pink or brown blood as your cervix begins to soften and dilate.
Having persistent lower back pain or increased pressure as the baby descends are also common signs that labor is a few days away.
You may also experience what is known as lightning crotch when labor is a few days away.
A good way to tell if labor is starting and determine when you should go to the hospital for labor is the 3-2-1 rule for labor, which is a first time parent guideline for pregnancy in which parents can use to help determine when the active labor has begun and to determine when it's time to call a midwife or go to the hospital for active labor.
The 3-2-1 rule for labor often means that contractions in labor are occurring every 3 to 5 minutes, for 2 hours and are lasting 1 minute or more.
In the 3-2-1 rule for labor, contractions are occurring every 3 to 5 minutes.
And the pattern of contractions occurring has been consistent for at least 2 hours.
And each contraction you have lasts for 60 seconds or 1 minute or longer, which is an indicator that you should go to the hospital or contact a midwife if you have a midwife.
For any subsequent pregnancies, a 5-1-1 rule is often used which goes by contractions being 5 minutes apart, 1 minute long, for 1 hour.
And although the 3-2-1 rule for labor is a common benchmark used for active labor, many doctors also advise that you go to the hospital if the contractions during labor are strong and consistent or if your water happens to break.
And some doctors also suggest a 3-1-1 rule in labor which is when the contractions are 3 minutes apart, 1 minute duration, for 1 hour.
During pregnancy the labor contractions are the regular tightening and relaxing of the uterine muscle, which dilate your cervix and move the baby down the birth canal.
The labor contractions feel like intense cramping or pressure in the lower back and abdomen, increasing in strength, frequency, and duration over time.
True labor contractions last 30-70 seconds, occurring 5-10 minutes apart initially, and do not stop with movement.
Early labor or the latent phase is when contractions are mild to moderate and 30 seconds to 45 seconds and are 5 minutes to 30 minutes apart.
Active labor during pregnancy is when the labor contractions become much stronger and more painful, often lasting seconds to 70 seconds and occur every 2 minutes to 3 minutes.
And the transition phase during labor is the most intense stage, with the labor contractions lasting 60 seconds to 90 seconds and are coming 2 to 3 minutes apart.
Labor contractions are caused by the body releasing oxytocin, which triggers your uterus to contract.
And the baby's head also puts pressure on your cervix, which also stimulates the cervix to stretch and open.
Contractions during pregnancy can be managed with epidural anesthesia during the active phase of labor or even warm showers or baths or by applying hot/cold packs to your back, massage or by changing positions.