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Parturition is the process of giving birth to a child. It is most commonly known as ‘childbirth’ which occurs after the complete development of the embryo.
- During parturition, the release of hormones such as oxytocin and estrogen takes place to start the production of milk and labor.
- This process occurs nine months after conception or fertilzation.
What is Parturition?
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The word ‘Parturition’ is derived from the Latin word parturire which means “to be ready to bear young”. It is a hormonal process of expulsion of a fully formed fetus from the uterus to the vagina to the outside world followed by painful uterine contractions.
- Parturition is also known as labor, delivery, or childbirth.
- It is the final stage of pregnancy which occurs approximately 36-38 weeks after fertilization.
- During childbirth, the pituitary glands release large amounts of oxytocin which is responsible for contractions.
- Another hormone that stimulates the uterus is cortisol. It is released in large amounts from the adrenal glands.
The Process of Parturition
Process of Parturition
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Parturition is induced by a complex neuroendocrine mechanism. This process begins when the fetus is fully developed, and the uterine wall contracts. This contraction is termed as the ‘fetal ejection reflexes’.
- This triggers the maternal pituitary gland to release oxytocin which acts on the muscles of the uterus and causes strong contractions.
- This in turn stimulates further oxytocin secretion. As oxytocin production increases, the uterine contractions would also increase causing labor pain.
- At the time of birth, the baby is pushed out by strong powerful contractions.
- Soon after the infant is delivered, the placenta is also expelled out of the uterus.
Stages of Parturition
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Parturition occurs in the following three stages:
- Dilation
- Expulsion
- Placental
Dilation
Dilation is the first stage of parturition and begins with the onset of labor. The hormone responsible for the dilation of the cervix is Relaxin. This stage is further divided into two sub-stages:
- Latent Phase - It lasts for about 8-12 hours or until the cervix dilates to about 1-2 cm. Irregular contractions occur every 5 - 30 minutes and last up to 30 seconds. This is followed by regular contractions that occur after every 3-5 minutes and lasts for more than a minute.
- Active Phase - In this phase, the cervix dilates from 3-10 cm. It is that stage where the cervix is fully dilated. The contractions are intense that last up to 60-90 seconds.
Dilation
Expulsion
After the complete dilation of the cervix, we enter the second stage of labor called expulsion. The hormone responsible for expulsion is oxytocin. The expulsion phase also takes place in two stages:
- Passive phase: The head of the baby navigates through the maternal pelvis and moves down the vagina.
- Active phase: The mother contracts the muscles of the abdomen followed by uterine contractions. When the baby is out, the umbilical cord that connects the baby to the placenta gets cut.
Expulsion
Placental
The placental stage occurs after the delivery of the baby and involves the removal of placenta. After the baby is delivered, the uterus contracts firmly and the placenta begins to separate from the uterine wall.
- It is carefully removed so that there are no placental remnants.
- The uterus contracts and comes back to normal in a few days.
Placental Delivery
Symptoms of Parturition
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After 38 to 40 weeks the following signs and symptoms of parturition take place:
- Fatigue and dizziness.
- Labor and uterine contractions.
- Mucosal discharge.
- Abdominal bloating.
- Development of mammary glands and production of milk.
- Swelling of vulva.
- Relaxed ligaments of the pelvis.
- Period-like cramps.
- Diarrhoea.
- Gush of water due to membrane break.
Things to Remember
- Parturition is the process of delivering a child through the vagina.
- The hormone responsible for uterine wall contractions is estrogen.
- Fetal distress is one of the major complications during childbirth.
- Relaxin is the hormone responsible for expanding the cervix.
- The mild uterine contractions experienced are called the ‘fetal ejection reflexes’.
Sample Questions
Ques. Which hormone is responsible for contractions of the uterus during parturition? (1 mark)
Ans. Oxytocin is also known as birth hormone. This hormone is released in the bloodstream as a hormone for dilation of the cervix and uterine contractions during labor.
Ques. What is parturition and gestation? (1 mark)
Ans. Parturition is the process of expelling the fully developed fetus from the vagina. The stage at which the embryo is fully formed is called gestation.
Ques. During which phase does the cervix dilate the most? (1 mark)
Ans. The cervix dilates the most during the Active Phase of dilation. The cervix dilates from 6-10 cm. During this stage, the cervix is 100% dilated.
Ques. What is meant by placental expulsion? (1 mark)
Ans. Placental expulsion also known as afterbirth is called the third stage of labor. It occurs when the placenta comes out of the birth canal just after the baby is expelled.
Ques. Why parturition is called a neuroendocrine mechanism? (2 marks)
Ans. Parturition is induced by a neuroendocrine mechanism.
- Once the fetus and placenta are completely developed, the initial stage of parturition begins.
- This results in contractions of the uterine wall and is called the ‘fetal-ejection reflex’.
These signals release the hormone oxytocin.
Ques. What connects the fetus to the maternal uterine wall? (1 mark)
Ans. An umbilical cord connects the fetus to the mother’s uterine wall. It carries food and oxygen from the placenta and carries waste from the fetus back to the placenta.
Ques. Does the baby pass easily through the birth canal? (1 mark)
Ans. In order to make it through the passage, the fetus makes several positional changes. Well the skull bones of the newborn haven’t really fused together yet so they slide over the top of each other a bit and compress the skull so that the baby can pass through the birth canal.
Ques. Mention the factors that determine how easy the passage is for the fetus. (3 marks)
Ans. The following factors determine how easy the passage is for the fetus.
- Fetal size - The vital factor is the size of the fetal head.
- Fetal attitude - It refers to the way the fetal body is flexed which includes the chin is on the chest, rounded back and flexed arms and legs. This position produces the smallest diameter. The fetuses which are not completely flexed have more difficulty in making through the passage.
- Fetal lie - This describes how the fetus is positioned in the uterus. A longitudinal fetal lie is ideal. The spine of the fetus lies along the spine of the mother.The fetal spine can also be transversal where the fetal spine is perpendicular to the spine of the mother or it can be oblique where it’s slightly at an angle. Transverse and oblique positions are not ideal for the expulsion of a baby.
Ques. What are the complications of parturition? (3 marks)
Ans. The following are the complications of parturition:
- Fetal distress: In this, the child’s heart rate decreases due to which a C-section is initiated.
- Nuchal cord: The umbilical cord, wraps around the neck of the baby. This might create complications, but is very rare.
- Breech: The baby’s head must be facing downwards at the time of delivery. A C-section is encouraged if the baby’s head is the other way around.
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