Chapter 19 - Birth And Infant Development

Question 1

What is gestation?

Answer 1

The period of pregnancy - the time that the embryo or foetus is carried in the uterus

Question 2

What is Parturition

Answer 2

The process by which the foetus is expelled from the mother’s body at the of gestation.

AKA- BIRTH

Question 3

What is labour?

Answer 3

Parturition is preceded by a sequence of events

Question 4

General - what occurs during gestation?

Answer 4

During this period (approximately 280 days)

• child grows to be approx 50cm
• average weight 3400g

Measured from beginning of the last menstrual Period because this date is known and date of fertilisation is not.
- date of birth is predicted on the Basis on this

Question 5

What occurs in preparation for labour? - HORMONAL CHANGES

Answer 5

Prep for labour - several hormonal changes occur which causes

1. LIGAMENTS of the PELVIS to soften - making them more PLIABLE for childbirth
2. INCREASES the RESPONSE of the UTERUS to STIMULI and STRENGTHEN CONTRACTION of its MUSCLES

Question 6

Explain the Before labour baby positioning

Answer 6

Before labour

1. FOETUS has probably SETTLED with its HEAD in the MOTHER’S PELVIS
   - 90% of time
   - position ALLOWS HEAD to be DELIVERED FIRST; acts as a WEDGE TO FORCE OPEN CERVIX AND VAGINA
   - allows foetus to BEGIN BREATHING EVEN BEFORE COMPLETELY FREE OF BIRTH CANAL
2. CERVIX has SOFTENED, SHORTENED in LENGTH and likely to HAVE begun to OPEN a LITTLE
3. FOETUS is usually facing the woman’s right or left HIP BONE, with its KNEES DRAWN UP its ABDOMEN and LEGS CROSSED
   - POSITION takes up LITTLE SPACE as possible
   - HEAD is usually PRESSED AGAINST the MOTHER’S BLADDER, the side other AGAINST her BOWEL.

Question 7

What occurs during the first stage of labour?

Answer 7

1. During the final three Months of gestation; Uterus undergoes weak, irregular contractions - Braxton Hicks ( practice)
   - gradually becomes stronger and frequent during final weeks of pregnancy.
2. LABOUR PAINS - STRONG MUSCLE CONTRACTIONS and every 30 mins
   - BEGINNING of BIRTH PROCESS
3. First stage of labour, the DILATION OF THE CERVIX is the time from the ONSET of LABOUR to the complete dilation (or OPENING) of the CERVIX.
   - average lasts 8-9 hours and for 2nd child approx 4hrs.
4. Similar to PERISTALSIS - WAVES of CONTRACTIONS TRAVEL from UPPER PART of UTERUS DOWNWARD to CERVIX.
   - each contraction the MUSCLE FIBRES MAKING UP the UTERUS SHORTEN a SMALL AMOUNT, PULLING ON the CERVIX.
5. Pull on CERVIX SHORTENS it so it no LONGER PROJECTS DOWN INTO THE VAGINA.
6. At the SAME TIME the CERVIX OPENS.
   - cervical dilation allows the foetus to MOVE more DEEPLY into the PELVIS.
7. As contractions become more frequent and stronger the head of the foetus is pushed more forcefully against the slowly dilating cervix.
8. Eventually CERVIX is COMPLETELY DIALATED (@10cm) and the UTERUS, CERVIX and VAGINA form a SINGLE CURVED passage - BIRTH CANAL
   - the ROUTE through which the foetus will pass, AIDED by CONTRACTIONS of the UTERUS and VOLUNTARY CONTRACTIONS of the ABDOMINAL MUSCLES of the mother,
9. COMPLETE DILATION of the CERVIX MARKS the END of the 1st STAGE OF LABOUR.

Question 8

What occurs during the second stage of labour? - DELIVERY OF FOETUS (STAGE OF EXPULSION)

Answer 8

1. FREQUENTLY BEGINS with the BURSTING of the MEMBRANE SURROUNDING the FOETUS and a GUSH of FLUID FROM the VAGINA.
   - May occur early in pregnancy. Or may not occur until foetus is ready to be born.
2. Foetus MOVES THROUGH the FULLY DILATED CERVIX
   - process from Full dilation lasts 20mins to 2hrs.
   - foetus Head STRETCHES VAGINA
3. DISTENSION OF VAGINA SIMULATES the WOMAN to CONTRACT her ABDOMINAL MUSCLES
   - OCCURS TOGETHER WITH the CONTRACTION of the UTERUS and PUSHES FOETUS OUT of Vagina
   * *BABY’s HEAD TURNS TO FACE MOTHER’s BACK
4. EACH CONTRACTION makes the HEAD to GRADUALLY ADVANCE
   - in between contractions it retreats a little
   - HEAD GRADUALLY moves THROUGH EXTERNAL OPENING of VAGINA
5. As this occurs HEAD BECOMES MORE VISIBLE
6. Eventually HEAD STRETCHES the VAGINA ENTRANCE and the TISSUES BETWEEN IT AND THE ANUS.
   - this TISSUE becomes TIGHTLY STRETCHED OVER FOETUS HEAD as it is forced into the world.
7. Once head emerged, it TURNS S again to FACE mother’s HIPS
   - this ROTATION allows SHOULDER and rest of BODY to MOVE more EASILY through birth canal.
8. As foetus PASSES THROUGH birth CANAL, the PRESSURE on the HEAD MAY cause it to be PUSHED out of SHAPE.
   - produces NO DAMAGE to underlying brain, as bones of SKULL are PLIABLE and separated by joints that allow some degree of overlap,
9. Head resumes normal shape a few days after birth.

Question 9

What occurs during the second stage of labour for MOTHER

Answer 9

Mother working very hard

1. PULSE RATE INCREASES
2. Begins to SWEAT from effort required
3. BETWEEN CONTRACTIONS mother tries to REST A LITTLE to GAIN SOME STRENGTH FOR NEXT EFFORT FOR CONTRACTIONS

Question 10

What occurs during the third stage of Labour?

Answer 10

1. Once BORN baby BEGINS to BREATHE with own lungs, even if still connected to umbilical cord.
2. UMBILICAL cord is CLAMPED, tided in two side and CUT between ties.
   - arteries and veins within the umbilical cord contract, either before or immediately after they are cut
   - after a few days umbilical cord dried and falls away.
   - the NAVAL OR UMBILICUS is all that REMAINS
3. At birth BABY COVERED IN VERNIX
   - PROTECTIVE LAYER - wash a baby with a thin layer left; therefore incidence of skin infections in babies decreased greatly
4. AFTERBIRTH — Uterus CONTINUES TO CONTRACT (up to 5mins after delivery) to deliver and expel AMNION, CHORION, REMAINS OF UMBILICAL CORD and PLACENTA
5. LITTLE BLOOD is LOST during this stage AS PLACENTAL BLOOD VESSELS CONSTRICT and CONTRACTIONS OF the UTERUS SQUEEZE SHUT the UTERINE VESSELS that SUPPLY BLOOD TO the PLACENTA.
6. BLOOD CLOTS then FORM to STOP all LEAKAGE of BLOOD
7. With LARGE AREA of EXPOSED TISSUE - INFECTION CAN OCCUR
   - today with strict standards of cleanliness and availability of sterile antibiotics women do not die due to infection after birth.

Question 11

What are some Characteristics of a new born baby?

Answer 11

Usually 3.4kg and 50cm
- range of sizes of subsequent rate of growth and gender

1. Head makes up 1/4 of overall length and legs only 1/3
2. Newborn HELD VERTICALLY under the arms, the head LOLLS FORWARD and BOWED LEGS hangs HELPLESSLY as MUCLSE CONTROL has NOT DEVELOPED.
3. From moment of birth baby can BREATHE, SUCK, SWALLOW and get RID OF WASTES
4. Can SEE (not extend of adults), TOUCH, TASTE, HEAR and TURN HEAD.
5. From first minutes of life - BABY CRIES OUT TI SIGNAL FOR HELP
6. REFLEXES GOVERN majority of movements
   - OCCURS AUTOMATICALLY in RESPONSE TO PARTICULAR STIMULUS
   Eg placing an object such as finger in baby’s mouth simulates sucking reflex - important reflex for a baby to obtain milk from breasts

Question 12

Changes in Mother After Childbirth

Answer 12

PUERPERIUM; lasts 8 weeks - Following childbirth Stage the

1. REPRODUCTIVE ORGANS eg Uterus, slowly RETURN TO THEIR NON-pregnant state.
   - after delivery uterus begins to contract
   - usually not painful but to some are painful
2. Within 2 weeks the mother is no longer able to feed the SWELLING within her abdomen and by end of PEUPERIUM the uterus has completed shrinking.
   - contractions and gradual shrivelling of the muscle fibres bring about the shrinking
   - FLATTENING ABDOMEN - one of the most visible
3. DISCHARGE OF FLIUD FROM THE SLOWLY SHRINKING UTERUS
   - fluid is MIXTURE of blood and the BREAKDOWN PRODUCTS OF TISSUES which is discharged as the uterus gradually becomes smaller
   - NORMALLY STOPS AT END OF 3rd Week (can be persistent up to 6)
4. BLOOD VOLUME returns to NORMAL (from increased to normal)
   - PULSE is SLOWER
5. body TEMPERATURE is ABOVE NORMAL
6. EMOTIONAL CHANGES
   - excitement to diminish
   - demands of baby taking a toll and POST NATAL OCCUR
   - third day blues appear for no apparent reason - mood changes may be just a way of adjusting to new situation
7. Return of MENSTRUATION shows that the REPRODUCTIVE SYSTEM is back to NORMAL after pregnancy.
   - if mother breastfeeding then menstruation is delayed 6months
   - STARTS only AFTER BREASTFEEDING - if NOT breastfeeding then can START AGAIN after 10weeks.

Question 13

Explain the Structure Of Breasts

Answer 13

Prior to puberty the Breasts in both sexes are similar

1. Age 10/11 in females
   - NIPPLE AREA BULGES and NIPPLE PROJECTS FROM the CENTRE
   - CAUSED by the INFLUENCE of HORMONES SECRETED by the OVARIES
   - the absence of signifying if such hormones in the males means if the males breast remain undeveloped
2. Female Breasts consist of 16-25 SECTIONS, Called LOBES
   - each which is DIVIDED INTO NUMBER of LOBULES
3. LOBULES
   - WALL OF EACH LOBULE is made large number of GLANDULAR AVEOLI; MILK SECRETING REGIONS of breasts
4. The LOBULES and LOBES are surrounded by FATTY CONNECTIVE TISSUE, which gives the BREASTS its rounded contour
5. these spaces serve as reservoirs for milk secreting for milk produced by the alveoli.
   - from each space a SHORT, STRAIGHT DUCT LEADS TO NIPPLE
6. EACH LOBE HAS ITS OWN MILK SPACE
   - are between 15 and 25 openings on the nipple for the secretion of milk.

Question 14

What is Lactation?

Answer 14

Lactation refers to the INITIATION and MAINTENANCE of milk secretion, was well as the DELIVERY OF MILK TO INFANT.

Question 15

Explain the process of lactation?

Answer 15

1. In early pregnancy - INCREASE in levels of CIRCULATING HORMONES CAUSES CHANGES IN THE BREASTS
2. The LOBES become MORE COMPLEX and LARGER in SIZE, and OIL SECRETING GLANDS around nipple ENLARGES.
3. 1-2 days AFTER BIRTH (or sometimes earlier) MILK SECRETION OCCURS.
4. FIRST SECRETION is WATERY, YELLOWISH-WHITE FLIUD called COLOSTRUM.
5. Although milk secretion begins shortly after birth, the MILK REMAINS STORED WITHIN BREAST UNTIL SUCKLING BEGINS.
6. Once NIPPLES are SUCKLED, AUTOMATIC Complex RESPONSE called MILK LET-DOWN REFLEX is TRIGGERED, and milk begins to flow.
7. As baby suckles there nipple, NERVES IN THE NIPPLE ARE STIMULATED AND MESSAGES ARE SENT TO THE BRAIN.
   - Brain instructs the PITUITARY GLAND to a hormone called OXYTOCIN.
8. OXYTOCIN triggers the CONTRACTION of small MUSCLES SURROUNDING the milk filled LOBULES of Breasts.
   - as a result milk is secreted EJECTED INTO DUCTS, — suckling infants can then draw the milk through the openings on the nipple.

Question 16

What measures need to be taken for Lactation = good.

Answer 16

Up to 1.5 L of milk may be formed each day.

To supply nutrients necessary for prolonged lactation, the mother must have well-balanced diet: 
Need Adequate supplies of 
- CALCIUM, 
- PHOSPHATE
- VITAMIN D 

OTHERWISE CALCIUM FOR MILK PRODUCTION MAY BE WITHDRAWN FROM HER OWN BONES AND TEETH.

Question 17

What does Colostrum consist of?

Answer 17

Similar composition to milk but contains NO FAT, AND HAS HIGH CONTENT OF MOTHER’s ANTIBODIES.

these ANTIBODIES can be ABSORBED through the INFANTS INTESTINES to give TEMPORARY IMMUNITY to those DISEASES to which MOTHER is IMMUNE TO.

Question 18

AT BIRTH BABY has to become SELF SUPPORTING - what does it do?

Answer 18

Before Birth - LUNGS do not function and obtains OXYGEN from the placenta.

Before Birth - ALIMENTARY CANAL does not FUNCTION and obtains NUTRIENTS from PLACENTA.

This important differences foetus and baby mean that the circulation must change when baby is born.

Question 19

Explain the Baby’s circulatory system when in Uterus.

Answer 19

1. Before birth, foetal blood is carried to placenta in 2 umbilical arteries.
2. As it CIRCULATES through the PLACENTA, CARBON DIOXIDE AND WASTES are exchanged for OXYGEN and NUTRIENTS
3. Blood Then RETURNS TO FOETUS via umbilical vein.
4. Some of the BLOOD returning to the FOETUS flows through the LIVER and into the INFERIOR VENA CAVA (main vein taking blood to heart from lower body)
5. The REMAINDER BYPASSES the LIVER by FLOWING THROUGH A VESSEL CALLED **DUCTUS VENOSUS and then to INFERIOR VENA CAVA.
   * fact that not all blood passes though liver is ok because mother’s liver serves the needs of the foetus.
6. Blood RETURNING to FOETAL HEART ENTERS RIGHT ATRIUM. from there it can follow several pathways.

Question 20

Blood RETURNING to FOETAL HEART ENTERS RIGHT ATRIUM. from there it can follow several pathways.

WHAT ARE THEY AND EXPLAIN THEM.

Answer 20

1. Blood may FLOW INTO RIGHT VENTRICLE and then to LUNGS in USUAL WAY.
   * however the lungs are collapsed and not functioning at this stage, so they offer considerable resistance to blood flow and little blood reaches the lungs.
2. MOST of the BLOOD from RIGHT VENTRICLE flows through **DUCTUS ARTERIOSUS to THE AORTA (artery carrying blood to body)
   - the DUCTUS ARTERIOSUS is a LUNG BYPASS that ALLOWS BLOOD in PULMONARY ARTERY to flow directly into aorta.
3. BLOOD IN RIGHT ATRIUM may FLOW DIRECTLY INTO LEFT ATRIUM through an oval OPENING between the 2 chambers called FORAMEN OVALE.
   - blood in right atrium goes through it via hole - beneficial as blood from placenta is highly oxygenated and can flow to the developing foetal tissues via Aorta quickly.

Question 21

What happens when baby does not breathe?

Answer 21

Baby’s first breath of life is usually triggered by shock of birth, if not

• slap on bottom provides stimulus that imitates breathing.
• failing previous method, CLAMPING OF UMBILICAL CORDS allows the level of CO2 in baby’s blood increases, stimulating the respiratory centre in brain and resulting in breathing.

Question 22

Explain what happens to baby during/after birth

Answer 22

At birth newborn no longer dependent on placenta for oxygen and food.

1. Lungs and liver must become fully functional, and for this to colour blood must flow through them.
2. Baby’s First Breath from shock or other stimuli.
3. As lungs expand the same resistance to blood flow, so blood flow through DUCTUS ARTERIOSUS begins to DECREASE.
4. A few WEEKS AFTER birth, all that is LEFT OF DUCTUS ARTERIOSUS is some FIBROUS TISSUE.
5. As LARGE AMOUNTS of blood return to the heart from the lungs, the pressure in the left atrium increases.
6. INCREASED PRESSURE FORCES the WALL OF the FORAMEN OVALE AGAINST the WALL of the ATRIUM - thus CLOSING OFF the OPENING.
7. EVENTUALLY the FORAMEN OVALE becomes PERMANENTLY CLOSED.

Question 23

Physical development of baby in the first year

Answer 23

1st year of life - extensive growth changes take place

• length increases by 1/3rd (approx 71-74cm)
• weight TRIPLES (9Kg)

Second part of 1st year

• overall body proportions change rapidly - not all parts grow at the same rate
• Eg leg vs head
• leg; at birth is 1/5 of length at maturity - from 2 months they grow rapidly
• head and face - grows very slowly (not as dramatic growth)
• 2 month of foetus head 1:2 ratio, birth 1:4, adult 1:10 of body length

Question 24

Physical development 2-15yrs of age

Answer 24

For the first few years - growth occurs at fast rate
But by age of 6 - physical growth slows down

6-11 years ;

• 5-6% per year height increase
• weight gained is a little over 10%

Until 10th year - males taller and bigger

15yrs- females- taller and bigger

By age 15 proportions are almost the same as those of adults.