Essential Factors in
Conception
©
Dr. Pam Williams, PhD, RNC-AWHC
Widener University
Sexual Development: Initiation of
Sexual Maturation
• Puberty occurs in an orderly sequence.
• Hypothalamus secretes gonadotropin-releasing
hormone (GnRH).
• Anterior pituitary secretes follicle-stimulating
hormone (FSH) and luteinizing hormone (LH).
• Ovaries and testes increase production of sex
hormones.
• Gametes mature in response to higher levels of
FSH and LH.
• Secondary sex characteristics develop.
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External Female
Reproductive Organs
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Internal Female
Reproductive Organs
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Fallopian tube and Ovary
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Female Reproductive Support
Structures: Bony Pelvis
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Female Reproductive Support
Structures: Muscles
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Female Reproductive Cycle
• Ovarian cycle
• Follicular phase
• Ovulatory phase
• Luteal phase
• Endometrial cycle
• Proliferative phase
• Secretory phase
• Menstrual phase
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Hereditary Influences: Structure of
Genes and Chromosomes
• DNA
• Basic building block of genes and chromosomes
• Sequence of base pairs determines which amino acids will be
assembled
• Genes
• Direct production of a specific product necessary for structure or
function
• Not all genes function at the same time
• Genes that code for the same trait have alternate forms
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What do you see?
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Multifactorial Disorders:
Characteristics
• Interaction between genetic susceptibility
and environment
• Present and detectable at birth
• Isolated defects
• May cause secondary defect
• Most common
• Heart defects
• Neural tube defects
• Cleft lip/palate
• Pyloric stenosis
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Multifactorial Disorders:
Risk for Occurrence
Factors of interest to a genetic counselor:
• Number of affected close relatives
• Severity of the disorder in family members
• Sex of affected person
• Geographic location
• Seasonal variations
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Environmental Influences
• May be positive or negative
• Teratogens
• Agents that cause birth defects
• Factors make it difficult to establish teratogenic potential
Causative agents:
Maternal infectious agents
Drugs
Pollutants
Ionizing radiation
Maternal hyperthermia
Maternal medical disorders
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Environmental Influences
• Preventing fetal exposure
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Ideally begins before conception
Infections
Drugs and other substances
Ionizing radiation
Maternal hyperthermia
• Manipulating the fetal environment
• Appropriate medical therapy for diseases
• 400 mcg of folic acid daily before conception
• Mechanical disruptions to fetal development
• Oligohydramnios
• Clubfoot
• Fetal lung development
• Fibrous amniotic bands
• Fetal deformations
• Intrauterine limb amputation
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Fertilization
Entry
Fusion
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Preembryonic Period
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Cell division
Entry of the zygote into the uterus
Implantation in the decidua
Maintaining the decidua
Location of implantation
Mechanism of implantation
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Placenta
• Transfer functions
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Gas transfer
Nutrient transfer
Waste removal
Antibody transfer
Transfer of maternal
hormones
• Endocrine functions
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Fetal Circulation
• Umbilical cord
• Two arteries
(deoxygenated blood)
• One vein (oxygenated
blood)
• Fetal circulatory
circuit
• Ductus venosus
• Ductus arteriosus
• Foramen ovale
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