HBHD 13e Ch24

Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins
Chapter 24
Development and Birth

Copyright © 2015 Wolters Kluwer • All Rights Reserved
Overview

Key Terms
abortion fetus oxytocin
amniotic sac gestation parturition
chorion human chorionic placenta
colostrum gonadotropin (hCG)
decidua implantation umbilical cord
embryo lactation zygote
fertilization obstetrics

Pregnancy
Learning Objectives
1. Describe fertilization and the
early development of the fertilized
egg.
2. Describe the structure and
function of the placenta.
3. Describe how fetal circulation
differs from adult circulation.
4. Name five hormones active
during pregnancy, and describe the
function of each.
5. Briefly describe changes that occur
in the embryo, fetus, and mother
during pregnancy.

Childbirth
Learning Objectives
6.Briefly describe the four stages of
labor.

The Mammary Glands and Lactation
Learning Objectives
7.Name five hormones active in
lactation, and describe the action
of each.
8. Cite the advantages of breast-
feeding.

Disorders of Pregnancy, Childbirth, and
Lactation
Learning Objectives
9.Describe four disorders associated
with the placenta.
10.Explain how breast cancer is
diagnosed and treated.
11.Cite four possible causes of
lactation disturbances.

Case Study
Learning Objective
12. Referring to the case study
and the text, discuss possible
causes of high-risk pregnancies.

Word Anatomy
Learning Objective
13. Show how word parts are used to build words
related to development and birth.

Pregnancy
• Pregnancy (gestation) begins with fertilization and ends
with childbirth
• Approximately 38 weeks
• All fetal tissues differentiate from a single fertilized egg
• Obstetrics
– Obstetrician

Pregnancy (cont.)
Fertilization and the Start of Pregnancy
•Vagina receives semen
•Sperm cells dissolve egg cell coating
•Sperm and egg combine to form a single cell (zygote)
– Zygote divides into cell cluster, morula, and moves
to uterus
– Blastocyst; implantation
• Inner cell mass; embryo
• Trophoblasts
•Fetus

Figure 24-1 Fertilization and implantation.
Where is the ovum fertilized?
Pregnancy (cont.)

Pregnancy (cont.)
The Placenta
•Consists of both maternal and embryonic tissue
– Decidua (maternal tissue)
– Chorion (embryonic tissue)
•Organ of nutrition, respiration, excretion for developing
offspring
•Chorion forms chorionic villi (projections)
– Chorionic villi create a network of venous sinuses
filled with maternal blood
•Blood of the mother and offspring do not mix

Pregnancy (cont.)
The Placenta (cont.)
•The umbilical cord
– Connects embryo to placenta
– Carries blood to and from embryo (later called the
fetus)
•Fetal circulation
– Circulatory adaptations to bypass nonfunctional
lungs.
– Umbilical vein from placenta carries oxygen-rich
blood to the liver
– Most blood added to oxygen-poor blood in inferior
vena cava via ductus venosus

Pregnancy (cont.)
• Fetal circulation (cont.)
– Foramen ovale in atrial septum bypasses right
ventricle and pulmonary circuit
– Ductus arteriosus connects pulmonary artery to
descending aorta
– Two umbilical arteries return blood to placenta for
oxygenation
– Adaptations close after birth of baby; failure to
close results in congenital defects

Figure 24-2 The placenta and the fetal circulation.
What is signified by the purple color in this illustration?
Pregnancy (cont.)

Pregnancy (cont.)
Hormones and Pregnancy
•Blastocyst produces human chorionic gonadotropin (hCG)
– Stimulates growth of corpus luteum
• Progesterone and estrogen
‒ Progesterone maintains endometrium and
helps prepare breasts for milk secretion
‒ Estrogen promotes enlargement of the uterus
and breasts
•Human placental lactogen (hPL)
•Relaxin

Pregnancy
✓
Checkpoints
24-1 What structure is formed by the union of an ovum
and a spermatozoon?
24-2 What structure nourishes the developing fetus?
24-3 What is the function of the umbilical cord?
24-4 Fetal circulation is adapted to bypass what organs?
24-5 What embryonic hormone maintains the corpus luteum
early in pregnancy?

Pregnancy (cont.)
Development of the Embryo
•Embryology is study of growth during first eight weeks of
life
•Heart and brain among first organs to develop
– Heart and blood vessels originate second week
•Primitive nervous system begins to form third week
•Limb buds form by end of first month
•Human appearance at end of second month

Pregnancy (cont.)
Development of the Fetus
•Period of fetal development is from Month 3 until birth
– Organs continue to grow and mature
– Ovaries form in females
•Trimesters
– Most rapid growth Months 4 to 6 (second trimester)
– Can determine sex (second trimester)
•Amniotic sac
•Vernix caseosa

Figure 24-3 Development of an embryo and early fetus.
Pregnancy (cont.)

Figure 24-4 Human embryos at different stages and early fetus.
Pregnancy (cont.)

Pregnancy (cont.)
The Mother
•Total period of pregnancy approximately 266 days (38 weeks)
– Period of pregnancy also given as 280 days or 40 weeks
from the last menstrual period (LMP)
•Mother supplies all food and oxygen and eliminates waste
materials
•Mother’s metabolism changes to increase output of several organ
systems
– Heart pumps more blood
– Lungs increase rate and depth of respiration
– Kidneys excrete nitrogenous wastes from both mother and
fetus
– Digestive system supplies additional nutrients

Pregnancy (cont.)
The Mother (cont.)
•Common disorders:
– Nausea and vomiting
– Urinary frequency
– Constipation

Figure 24-5 Midsagittal section of a pregnant uterus with
intact fetus.
What structure connects the fetus to the placenta?
Pregnancy (cont.)

Pregnancy (cont.)
The Use of Ultrasound in Obstetrics
Safe, painless, noninvasive method used to:
•Diagnose pregnancy
•Judge fetal age
•Determine location of placenta
•Show presence of excess amniotic fluid and fetal
abnormalities

Figure 24-6 Sonography.
Pregnancy (cont.)

Pregnancy (cont.)
✓
Checkpoints
24-6 At about what time in gestation does the heartbeat
first appear?
24-7 What is the name of the fluid-filled sac that holds
the fetus?
24-8 What is the approximate duration of pregnancy in
days from the time of fertilization?

Childbirth (cont.)
Factors That Start Labor
• Uterine muscle stretching stimulates prostaglandin
production
• Pressure on the cervix stimulates posterior pituitary to
release oxytocin
• Placenta changes
• Fetal cortisol inhibits mother's progesterone
• Increase of estrogen relative to progesterone

Childbirth (cont.)
Positive Feedback and Oxytocin
•Positive feedback much less common than negative
•Intensifies a response
•Activities continue until:
– Resources are exhausted
– Stimulus is removed
– Interruption by outside activity
•Oxytocin
– Cervical stretching stimulates the pituitary to
release oxytocin
– Contractions are stimulated

Figure 24-7 Comparison of positive and negative feedback.
What possible forces can
stop a positive feedback
system?
Childbirth (cont.)

Childbirth (cont.)
The Four Stages of Labor
Parturition is the process by which the fetus is expelled from the
uterus.
1.Stage 1: Uterine contractions
2.Stage 2: Begins when the cervix is dilated and ends with birth
of the baby
3.Stage 3: Begins after the child is born and ends with the
expulsion of the afterbirth (placenta)
4.Stage 4: Begins after expulsion of the afterbirth and
constitutes a period in which bleeding is controlled

Figure 24-8 Stages of labor.
Childbirth (cont.)

Childbirth (cont.)
Cesarean Section
•Incision made in the abdominal wall and uterine wall for
fetal delivery
•May be required for:
– Placental abnormality
– Abnormal fetal position
– Disproportion between the head of fetus and mother’s
pelvis

Childbirth (cont.)
Multiple Births
Twins occur in about one of every 80 to 90 births; triplets occur
about once in several thousand births.
•Twins:
‒ Fraternal
• Two different ova
• Two placentas and surrounding sacs
‒ Identical
• Single ovum
• Embryonic cells separate into two units
• Usually single placenta
• Separate umbilical cords
• Always same sex

Figure 24-9 Twins.
Childbirth (cont.)

Childbirth (cont.)
Pregnancy Outcomes
•Term infant
•Live birth
– Preterm
• Low birth weight
• Immature in development

Childbirth (cont.)
Pregnancy Outcomes (cont.)
•Loss of fetus
– Abortion
• Spontaneous abortion (miscarriage)
• Induced abortion
• Therapeutic abortion
– Fetal death
– Stillbirth
•Viability
– Apgar score

Childbirth (cont.)
✓
Checkpoints
24-9 What pituitary hormone stimulates uterine
contractions?
24-10 What is parturition?
24-11 During what stage of labor is the afterbirth
expelled?
24-12 What surgical procedure is used to remove a fetus
manually from the uterus?
23-13 What term describes a fetus able to live outside the
uterus?

The Mammary Glands and Lactation (cont.)
Structure of the Mammary Glands
•Lobes composed of glandular tissue and fat
•Secretions conveyed through lactiferous ducts
Function of the Mammary Glands
•Provide nourishment for the baby after its birth
•Colostrum; first mammary secretion
•Milk secretion begins within a few days after birth
– Positive feedback
Advantages of Breast Milk
•Avoids infections that may be transmitted by foods
•Contains maternal antibodies
•Proportions of nutrients perfectly suited to infant
•Psychological and emotional benefits

Figure 24-10 Section of the breast (mammary gland).
What muscle
underlies
the breast?

✓
Checkpoints
24-14 What are the ducts that carry milk out of the
breast?
24-15 What substance is secreted by the breast before
milk production begins?

Lactation (cont.)
Pregnancy-Related Disorders
•Ectopic pregnancy
•Placental disorders
– Abruptio placentae
– Placenta accreta
– Hydatidiform mole
– Choriocarcinoma
•Gestational diabetes (GDM)
•Pregnancy-induced hypertension (PIH) (preeclampsia)
– Eclampsia

Figure 24-11 Ectopic pregnancy.
Disorders of Pregnancy, Childbirth, and Lactation
(cont.)

Figure 24-12 Placental abnormalities.
(cont.)

Lactation (cont.)
Postpartum Disorders
•Puerperal infection
•Postpartum depression (PPD)
– May follow within a year of childbirth
– Occurs in about 10% to 20% of new mothers
– “Postpartum blues” or “baby blues”

Lactation (cont.)
Disorders of the Breast and Lactation
•Breast cancer
– Risk factors
• Over 40 years old
• Family history
• Factors that increase exposure to estrogen
‒ Early onset of menstruation
‒ Late menopause
‒ Late or no pregnancies
‒ Long-term menopausal hormone therapy

Lactation (cont.)
Disorders of the Breast and Lactation (cont.)
•Breast cancer (cont.)
– Mammogram
– Ductal carcinoma in situ (DCIS)
– Breast cancer treatment
• Radiation
• Chemotherapy
• Lumpectomy
• Mastectomy

Lactation (cont.)
Disorders of the Breast and Lactation (cont.)
•Lactation disturbances
– Malnutrition, dehydration, anemia
– Emotional disturbances
– Abnormalities or injuries to the mammary glands
– Mastitis

Figure 24-13 Breast cancer.
(cont.)

Lactation (cont.)
✓
Checkpoints
24-16 What is the term for a pregnancy that develops
outside the uterine cavity?
24-17 What is puerperal infection?
24-18 What is a radiographic study of the breast called?

Case Study (cont.)
Some causes for high-risk pregnancy:
•Pregnancy-induced hypertension (PIH) (preeclampsia)
– Hypertension, protein in the urine (proteinuria),
general edema, sudden weight gain
– HELLP is an acronym for hemolysis, elevated liver
enzymes, low platelet count
• Serious variant of preeclampsia
•Age (teen or first pregnancy after 35 years old)
•Chronic disorders such as uncontrolled diabetes mellitus,
kidney disease, hypertension, or clotting disorders
•Thyroid disease
•Autoimmune disease

Case Study (cont.)
• Trauma
• Poor maternal health
• Structural abnormalities of the mother’s reproductive
organs, such as uterine fibroids
• Acute maternal infections (e.g., Listeria or Toxoplasma)

Word Anatomy
Learning Objective
13. Show how word parts are used to build words related
to development and birth.

Word Anatomy (cont.)

HBHD 13e Ch24

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HBHD 13e Ch24