Chapter 24 - Pregnancy And Development

Question 1

Differentiate between an embryo and a fetus

Learning objective

Answer 1

Until the end of the eighth week of development, the offspring is called an embryo. At this point, the basic structural form of the human body is recognisable.

Starting with the ninth week and lasting until birth, the offspring is called a fetus, with simple versions of all organs present.

These organs and other structures enlarge and become specialised as the fetus develops.

Question 2

Discuss the birth process and explain the role of hormones in this process.
(Learner objective)

Answer 2

The birth process begins hours or days before birth, and the act of giving birth is called labour. Progesterone declines, and contractions are no longer suppressed.

A prostaglandin is synthesised that promotes these contractions as the cervix thins and opens.

Late in pregnancy, uterine and vaginal tissue stretch.

Nerve impulses are initiated to the hypothalamus, signalling oxytocin to be released from the posterior pituitary gland, stimulating powerful uterine contractions.

Rhythmic muscular contractions begin moving from the top to the bottom of the uterus.

In normal position, the foetuses head is forced against the cervix, stimulating even stronger labour contractions.

The cervix continues to dilate, and more oxytocin is released.

Abdominal wall muscles contract, helping to force the fetus through the cervix and vagina.

Question 3

Teratogens

Answer 3

Are environmental factors that cause congenital malformations by interfering with prenatal growth or development.

Question 4

External reproductive organs can be seen by which week of pregnancy

Answer 4

12th week

Question 5

Which month do you start feeling movement of the fetus

Answer 5

Fifth month

Question 6

The final systems to mature are the

Answer 6

Digestive and respiratory systems, hence many babies have difficulty breathing and digesting milk from the mother

Question 7

Parturition

Answer 7

Birth

Question 8

Birth process

Answer 8

Pregnancy ends with the birth process, which begins hours or days before birth.

The act of giving birth is called labor.

Question 9

Stages of labour

Answer 9

The first stage of labour is the dilation of the cervix.

The second stage, called the expulsion stage, is when the fetus emerges from the vagina.

The final placental birth stage is when the placenta is expelled from the uterus.

Question 10

Oxytocin

Answer 10

Nerve impulses are initiated to the hypothalamus, signalling oxytocin to be released from the posterior pituitary gland.

This hormone stimulates a powerful uterine contractions in the later stages of labour.

A false labour occurs when a regular spasms occur in uterine musculature.

Rhythmic muscular contractions begin moving from the top to the bottom of the uterus, which is the beginning of true labour.

Question 11

Episiotomy

Answer 11

If the fetus cannot pass through the vaginal canal because it is too narrow, an episiotomy me may be performed, which temporarily enlarges the passageway by cutting through the perineal musculature.

The episiotomy prevents the mother from experiencing jagged perineal tearing and can be sutured back together easily after the birthing process is complete.

Question 12

C-section

Answer 12

When complications occur during dilation or expulsion, the infant can be delivered through cesarian section (C section).

An incision is made through the wall of the abdomen, and the uterus is opened wide enough to allow the infants head to pass. Caesarean sections today represent nearly 1/3 of all live births.

Question 13

Afterbirth

Answer 13

Once the fetus has been born, the placenta separates from uterine wall and is expelled through the birth canal.

This expulsion is known as after birth and is accompanied by bleeding because of the separation from the uterine wall, which damages vascular tissues.

Oxytocin compresses the bleeding vessels and minimises blood loss.

Later, breastfeeding also contributes to returning the uterus to its original size, via stimulation of oxytocin release from the posterior pituitary .

Question 14

After the birth of a newborn, health is assessed in five ways:

Answer 14

Breathing
Heart rate
Skin colour
Muscle tone
Reflex response

These are assessed in an Apgar score, with each component given a score between 0 and 2. A total score of 8 to 10 indicates the baby is healthy.

Question 15

Breech birth

Answer 15

In only 3 to 4% of deliveries, a breach birth occurs, in which the infants legs or buttocks enter the vaginal canal before the head.

Breach births have higher risk of harm to the infant.

This is primarily because the umbilical cord can become constricted and cut off placental bloodflow.