The 29th week of pregnancy marks the start of the third and final trimester. At the start of this trimester, a woman is feeling well but as time passes, her discomfort increases. The baby has little room left in the womb and the body begins to prepare for labor. As the due date nears, the signs of labor and the end of pregnancy become more noticeable.
The third trimester is full of discomforts until the baby arrives. The baby's weight puts strain on the mother's back, making the pain more intense than it has been so far. Breathing can become more difficult as the uterus expands just below the diaphragm. The MayoClinic.com suggests that weight gain, spider veins, swelling, urinating and heartburn increase during the last trimester of pregnancy.
Lightening is a term used to describe the baby dropping down into the pelvis in preparation for labor. Breathing often becomes easier for the mother and heartburn may diminish. The DrSpock website calls this engagement and says it can occur weeks or days before labor. Some women may not have lightening until labor has actually started.
The cervix is thick and closed during pregnancy. A mass of mucus acts as a plug that fills the small cervical opening. This is called the mucus plug. As the baby's weight pushes downwards, the cervix can start to ripen, or become favorable for labor. As the cervix ripens it becomes thinner, called effacing and the opening gets wider, called dilation. Some medical professionals may perform a cervical check during the last few prenatal appointments to assess a woman's progress towards labor. Some women may be slightly effaced and dilated a few weeks before her due date.
As the cervix dilates the mucus plug loosens. This can pass gradually or in one large mass of mucus with a great deal of vaginal discharge. The What to Expect website describes the passing of the mucus plug as consisting of a stringy mucus discharge that is tinged with pink or brown coloration. This is commonly called "bloody show" and indicates labor may occur within a few hours or a few days.
Early Labor Phase
The American Pregnancy Association explains that the early labor phase starts from the onset of labor until the cervix has dilated to 3 cm. Some women may dilate a few centimeters without having contractions or not even realize that early labor has begun until contractions begin. Once the contractions start, the early labor phase will last about eight to 12 hours. Contractions last about 30 to 45 seconds with a five to 30 minute break in between each one. The pain of the contractions may feel the same as menstrual cramps. The bag of uterine water may break during this phase or later in the active labor phase.
Active Labor Phase
Once the cervix has dilated 4 cm, the active labor phase begins. The American Pregnancy Association suggests this phase lasts about three to five hours. Contractions get longer, strong and closer together. The mother should head to the birthing facility during this phase. The overseeing medical professional may have instructed her when to come to the facility, such as when the contractions last 60 seconds and occur six minutes apart for at least 60 minutes.
Transition may be the hardest phase of labor. This is when the cervix dilates from 8 cm to 10 cm. Contractions last about 60 to 90 seconds with 30 seconds to two minutes of rest in between, according to the American Pregnancy Association. This phase lasts between 30 minutes and two hours.
Once the cervix has dilated 10 cm, the woman will feel ready to push. This phase lasts between 20 minutes and two hours, according to the American Pregnancy Association. Contractions last 45 to 90 seconds with three to five minute breaks in between. With the contractions and pushing the baby will eventually crown, meaning the head appears. More pushing will lead to the delivery of the baby.