6.2: Birth process

Onset of Labor

Childbirth typically occurs within a week of a woman’s due date, unless the woman is pregnant with more than one fetus, which usually causes her to go into labor early. As a pregnancy progresses into its final weeks, several physiological changes occur in response to hormones that trigger labor.

A common sign that labor is beginning is the so-called “bloody show.” During pregnancy, a plug of mucus accumulates in the cervical canal, blocking the entrance to the uterus. Approximately 1–2 days prior to the onset of true labor, this plug loosens and is expelled, along with a small amount of blood, and the cervix begins to dilate.

As labor nears, the mothers’ pituitary gland produces oxytocin. This begins to stimulate stronger, more painful uterine contractions, which—in a positive feedback loop—stimulate the secretion of prostaglandins from fetal membranes. Like oxytocin, prostaglandins also enhance uterine contractile strength. The fetal pituitary gland also secretes oxytocin, which increases prostaglandins even further.

And the stretching of the cervix by a full-term fetus in the head-down position is regarded as a stimulant to uterine contractions. Combined, these stimulate true labor.[1]

Stages of Birth for Vaginal Delivery

In a natural birth, there are three stages that occur.

The First Stage

Uterine contractions signify that the first stage of labor has begun. These contractions may initially last about 30 seconds and be spaced 15 to 20 minutes apart. These increase in duration and frequency to more than a minute in length and about 3 to 4 minutes apart. Typically, doctors advise that they be called when contractions are coming about every 5 minutes. Some women experience false labor or Braxton-Hicks Contractions, especially with the first child. These may come and go. They tend to diminish when the mother begins walking around. Real labor pains tend to increase with walking. In one out of 8 pregnancies, the amniotic sac or water in which the fetus is suspended may break before labor begins. In such cases, the physician may induce labor with the use of medication if it does not begin on its own in order to reduce the risk of infection. Normally this sac does not rupture until the later stages of labor.

The first stage of labor is typically the longest. During this stage the cervix or opening to the uterus dilates to 10 centimeters or just under 4 inches. This may take on average 12-16 hours for first children or about 6-9 hours for women who have previously given birth.

Figure \(\PageIndex{1}\): Early cervical dilation – on the left is the elongated and nondilated cervix, whereas on the right, the cervix is fully effaced and dilated with the head of the baby entering the birth canal.[2]

The Second Stage

Figure \(\PageIndex{2}\): Full dilation and expulsion of the newborn going from 1. Presentation of the head (outside the vagina) 2. Rotation and delivery of anterior shoulder, 3. Delivery of posterior shoulder and 4. Delivery of the lower body and umbilical cord.[4]

The Third Stage

Figure \(\PageIndex{3}\): In the third and final stage of birth, the placenta detaches and exits through the vagina. Doctors check to make sure it is all there since any remaining piece inside the pregnant person can lead to infection and toxicity.[6]

Additional Considerations

More than 50% of those giving birth at hospitals use an epidural anesthesia during delivery (American Pregnancy Association, 2021). An epidural block is a regional analgesic that can be used during labor and alleviates most pain in the lower body without slowing labor. The epidural block can be used throughout labor and has little to no effect on the baby. Medication is injected into a small space outside the spinal cord in the lower back. It takes 10 to 20 minutes for the medication to take effect. An epidural block with stronger medications, such as anesthetics, can be used shortly before a Cesarean Section or if a vaginal birth requires the use of forceps or vacuum extraction.[7]

Persons giving birth can also receive other pain medications (although medications given through injection can have negative side effects on the baby). In emergency situations (such as the need for a C-section), they may be given general anesthesia. They can also choose not to utilize any pain medications. That is often referred to as natural childbirth.

Figure \(\PageIndex{4}\): In the LeBoyer method, the pregnant person sits and delivers the baby in a tub of warm water.[8]

Individuals can also use alternate positions (including standing, squatting, being on hands and knees, and using a birthing stool) and laboring, and even delivering in tubs of warm water to help relieve the pain of childbirth (see alternate methods described in the table section alternatives for childbirth).

Medical Interventions in Childbirth

Sometimes pregnant individuals cannot go into labor on their own and/or deliver vaginally. Let’s look at induction of labor and Cesarean Sections.

Induction

Sometimes a baby’s arrival may need to be induced before labor begins naturally. Induction of labor may be recommended for a variety of reasons when there is concern for the health of the pregnant individual or baby. For example:

• The pregnant person is approaching two weeks beyond their due date and labor has not started naturally
• Water has broken, but contractions have not begun
• There is an infection in the uterus
• The baby has stopped growing at the expected pace
• There is not enough amniotic fluid surrounding the baby
• The placenta peels away, either partially or completely, from the inner wall of the uterus before delivery
• The pregnant person has a medical condition that might put them or their baby at risk, such as high blood pressure or diabetes (Mayo Clinic, 2014).

C-sections

A Cesarean Section (C-section) is surgery to deliver the baby by being removed through an incision in the abdominal and uterine wall. In the United States, about one in three people have their babies delivered this way (Martin et al., 2015). Most C-sections are done when problems occur during delivery unexpectedly. These can include:

• The pregnant individual is carrying more than one baby (twins, triplets, etc.)
• The pregnant individual has health problems, including HIV infection, herpes infection, and heart disease
• The pregnant individual has dangerously high blood pressure
• The pregnant individual has problems with the shape of their pelvis
• There are problems with the placenta
• There are problems with the umbilical cord
• There are problems with the position of the baby, such as breech where the head is not in the downward position
• The baby shows signs of distress, such as a slowed heart rate
• The pregnant individual has had a previous c-section

Figure \(\PageIndex{5}\): A person receiving a C-section lies flat on their back as doctors/nurses take the baby out surgically through a cut in the abdomen.[9]

Figure \(\PageIndex{6}\): A baby being delivered by C-section in a surgical procedure.[10]

Although the surgery is relatively safe for adult and baby, it is considered major surgery and carries health risks. Additionally, it also takes longer to recover from a C-section than from vaginal birth. After healing, the incision may leave a weak spot in the wall of the uterus. This could cause problems with an attempted vaginal birth later. In the past, doctors were hesitant to allow a vaginal birth after a C-section. However, now more women who have a C-section go on to have a vaginal birth later.[11] This is referred to as a Vaginal Birth After Cesarean (VBAC).

Attributions:

Child Growth and Development by Jennifer Paris, Antoinette Ricardo, and Dawn Rymond, 2019, is licensed under CC BY 4.0

[1] 28.4 Maternal Changes During Pregnancy, Labor, and Birth by Lindsay M. Biga, Sierra Dawson, Amy Harwell, Robin Hopkins, Joel Kaufmann, Mike LeMaster, Philip Matern, Katie Morrison-Graham, Devon Quick, and Jon Runyeon is licensed under CC BY-NC-SA 4.0

[2] Image by OpenStax is licensed under CC BY 3.0

[3] Lifespan Development: A Psychological Perspective (page 60) by Martha Lally and Suzanne Valentine-French is licensed under CC BY-NC-SA 3.0

[4] Image by OpenStax is licensed under CC BY 3.0

[5] Lifespan Development: A Psychological Perspective (page 60) by Martha Lally and Suzanne Valentine-French is licensed under CC BY-NC-SA 3.0

[6] Image by OpenStax is licensed under CC BY 3.0

[7] Lifespan Development: A Psychological Perspective (page 60) by Martha Lally and Suzanne Valentine-French is licensed under CC BY-NC-SA 3.0

[8] Image by U.S. Army Alaska is licensed under CC BY 2.0

[9] Image by Tammra M is licensed under CC BY 2.0

[10] Image by Patricia Prudente on Unsplash

[11] Osterman, M.J.K. (2020). Recent trends in vaginal birth after Cesarean delivery: United States, 2016-2018. National Center for Health Statistics, Data Brief 359. In Centers for Disease Control, in the public domain.

Child and Adolescent Psychology by Florida State College at Jacksonville; Troianne T. Grayson; Mary Wuergler; and Michael Konrad is licensed CC-BY 4.0