Chapter 3 - Prenatal Development, Birth, and the Newborn

Postnatal, Perinatal, Prenatal

Postnatal - After birth

Perinatal - Hours/days around the birth period

Prenatal - before birth

Stage 1 of Birth

Longest of the three stages, lasts up to 9 hours

-uterine contracts are 15-20 minutes apart, lasting up to a minute

-Contractions cause the cervix to strech and open

As first stage progresses, contractions come closer together appearing every 2-5 minutes

Contractions dilate cervix to an opening of 10cm so baby can move from uterus to birth canal

Stage 2 of Birth

Begins when the baby’s head moves through the cervix and ends with the baby’s complete emergence

Stage 3 of Birth

Placenta, umbilical cord and other membranes are detached and expelled

-If placental product is retained, it will decay and cause various fertility problems

Placenta and Umbilical Cord

Placenta - center of the transfer of nutrients/waste between mother and child

Umbilical Cord - assists in the circulation of blood and nutrients

-important source of stem cells

Hospitals during Birth

Allow the mother and her obstetrician a range of options regarding their method of delivery

-medication; three basic kinds of drugs used for labor are:

1. Analgesia - pain relief, tranquilizers, barbiturates, narcotics

2. Anesthesia - block sensation, alter consciousness (epidural block)

3. Oxytocin/Pitocin - stimulates contractions

Doula

Person familiar with childbirth not apart of the medical staff, but provides emotional and physical support throughout labour/delivery

-Can be family or close friend

-Helps person use techniques to manage pain, act as advocates, provide support, etc

Doulas can help reduce need for medication and labours tend to be shorter with greater satisfaction

Midwives

Trained healthcare professional, can be present in both home births but also hospital births

-Provide care throughout pregnancy and for several weeks after birth

Apgar Score

Used to assess health of newborns at one and five minutes after birth

-Evaluate infant’s heart rate, respiratory effort, muscle tone, body colour, and reflex irritability

-Reflexes should be quick, automatic, and not under conscious awareness

Ex; Grasp Reflex - grasping at anything placed in the palm

Score of 7-10: Excellent

Score of 5-6: Fair, some intervention

Score of <3: Intervention needed

Weight Classifications for Newborns

Low Birth Weight - less than 2.5kg

Very Low Birth Weight - less than 1.5kg

Extremely Low Birth Weight - less than 1.0kg

Pre-Term Infant - infant born before 37 weeks

Birth Weight as a Predictor

Birth weight is most reliable predictor of long-term outcomes

-Lower birth weight = more intervention necessary

Small for Date Infants (Small for Gestational Age)

Birth weight below normal when length of pregnancy considered

-Weight less than 90% of all babies of the same gestational age

-Small for date infants may be preterm or full term

Risk Factors for Preterm/Low Birth Weight

-Births to women 35 years and older

-Multiple births (twin, etc)

-Management of maternal and fetal conditions

-Increased substance abuse

Ex; Drugs, smoking, drinking, poor nutrition

-Increased stress

Ex; life, social, job, economic stressors

Socioeconomic status can also be a predictor of birth weight

Premature Births and Education

The more premature the birth, the higher the rate of dropping out of school

-Low birth weight is related to premature births —> low birth weight related to education

Interventions of Low Birth Weight/Premature Births

1. Kangaroo Care - Holding newborn baby in upright position to promote skin-to-skin contact

• Assists in temperature regulation and release of oxytocin

2. Massage Therapy - Applying subtle pressure to relieve muscle tension by reducing cortisol (stress-hormone), helping to promote weight-gain

Postpartum Period

Period after childbirth lasts for about 6 weeks or however long it takes for a mother to achieve a pre-pregnancy state

-Time when woman adjsuts, physically and psychologically, to childbearing

-Adjustments needed are physical, emotional, and psychological

Involution

Return of the uterus to its pre-pregnancy size requiring muscle contractions

-Oxytocin - helps promote the contraction of the uterus, breastfeeding promotes oxytocin release to help mother’s body return to pre-pregnancy state

Postpartum Depression

Major depressive episode that typically occurs about 6 weeks after delivery

-Symptoms: Negative mood/affect, loss of interest in previously interested activities, loss of appetite, sleep disturbance, emotional fluctuations

-Prevalence: 3-20%, likely an underestimate since referrals are needed

Treatment: Anti-depressants, CBT, exercise

Role of Father’s Support

-Father’s support/caring can play a role in whether mother develops postpartum depression

-Higher support by fathers was related to lower incidence of postpartum depression in women

Prenatal Development

Begins with fertilizations, lasts 37-40 weeks (ends at birth)

-Divided into three periods:

1. Germinal (Period of Zygote)

2. Embryonic

3. Fetal

Contraception vs Contragestive

Contraception - Intervention that prevents egg from being fertilized

-Ex; birth control that prevents release of egg from ovary, IUD

Contragestive - Intervention that prevents implantation of blastocyst onto uterine wall

-Ex; Using mithopristone (RU-46)

Ectopic Pregnancy - Zygote develops within fallopian tube, non-viable

Germinal Period

Begins 2 weeks after conception

-Creation of fertilized egg (Zygote), cell division, and attachment of Zygote to uterine wall

-Rapid cell division by Zygote continues throughout germinal period

Ends in Implantation - attachment of Blastocyst to uterine wall, takes place 11-15 days after conception

Differentiation of Cells

Blastocyst consists of inner mass of cells that develop into embryo

-Trophoblast - outer layer of cells that provide nutrition and support for embryo

Embryonic Period

Begins 2-8 weeks after conception

-Rate of cell differentiation intensifies

-Support systems for cells that form organs appear

Layers of the Embryo

Endoderm - Inner layer of cells, develops into digestive/respiratory systems (produces internal body parts)

Mesoderm - Middle layer, develops into circulatory/excretory/reproductive systems, bones, and muscles (produces parts that surround internal areas)

Ectoderm - Outermost layer, develops into nervous system, brain, and sensory receptors (produces surface parts)

Life Supports of the Embryo

Amnion - Bag containing clear fluid in which developing embryo floats, maintains homeostasis of pressure for the lungs of the embryo to develop

Umbilical Cord - Contains two arteries and one vein, connects baby to placenta

Placenta - Disk-shaped group of tissues, small blood vessels from mother/offspring intertwin but do not join

Umbilical Veins and Arteries

Are intertwined

-Arteries - Carry deoxygenated blood/waste away from embryo

-Veins - Carry oxygenated blood/nutrients towards the embryo

Chorionic Villus

Network of capillaries within the placenta, site of diffusion of nutrients, waste and oxygen between umbilical veins/arteries and maternal veins/arteries

Amniocentesis

Needle that extracts sample from amniotic fluid to diagnose genetic disorder

-Done only after 24 weeks

Chorionic Villus Sampling (CVS)

Sample from CV tissue taken

-Can be performed earlier than amniocentesis

Organogenesis

Process of organ formation during first 2 months of prenatal development

-organs are especially vulnerable while being formed to environmental changes (“Sensitive Period”)

Fetal Period

Last 2 months of prenatal development; fatty tissues develop, functioning of organ systems (heart, kidneys) step up

-During 8/9th months fetus grows longer and gains substantial weight (another 2kg)

Average NA baby weights 7 pounds and is about 20 inches

Brain during Prenatal Devleopment

Basic structure of the brain is assembled during first 2 trimesters

-Third trimester of prenatal development and first 2 years of postnatal life are characterized by connectivity and functioning of neurons dependent on environmental experience

Input from environment is required for specialized brain regions

Neuronal Migration

6-24 weeks after conception

-Cells move outward from point of origin to appropriate location, creating different levels/structures/regions of the brain

-After migrating, it matures and develops more complex structures

Neural Tube

Long, hollow tube on the Embryo’s back, forms 18-24 days after conception out of the ectoderm

-Develops into the Nervous System

-Neural tube most close for neurogenesis to occur

Neurogenesis

Once neural tube closes, proliferation of new immature neurons take place

-Generation of new neurons is called neurogenesis

Anencephaly and Spina Bifida

Birth defects related to failure of neural tube to close

-Spina Bifida - Stems from vitamin B deficiency, leads to paralysis/cognitive impairment

Teratogen

Agent that causes malformation, birth defect, or negative psychological/behavioural outcomes

-”Tera” is greek for “Monster

Includes drugs, incompatible blood types, environmental pollutants, infectious disease, deficiencies, maternal stress, advanced maternal/paternal age

Factors that Influence Severity of Damage by Teratogen

1. Dose

2. Genetic susceptibility (genetics of fetus/mother)

-Ex; High levels of PCBs impacting male birth rates, ability of mother to metabolize alcohol

3. Time of exposure to particular teratogen (critical period)

-Greatest sensitivity to teratogens is during the embryonic period

-Sensitivity of systems/limbs can differ from each other

Factors make it difficult to predict effect of teratogen

Examples of Teratogen

Filidomide - medication for morning sickness, causes major birth defects

Accutane - medication for acne, harmful teratogen

Damage during Germinal vs Embryonic Period

Damage during germinal period may prevent implantation

-In general, embryonic period is more vulnerable than the germinal

Types of Teratogen

1. Prescription Drugs

2. Non-Prescription Drugs

3. Psychoactive Drugs

• Alcohol - Fetal Alcohol Spectrum Disorders

• Nicotine

• Illicit drugs, cocaine, methamphetamine, heroin

4. Environmental Hazard

5. Emotional states/stress

6. Disease and Functions

Baby Addiction to Opioid Treatment

Methadone can be used to reduce fentanyl/morphine addiction babies

Genital Herpes

Herpes infection during birth can risk transmission to the baby

Acetaminophen vs NSA

NSA includes Advils, Aleve

-NSA are teratogenic to liver/levels of amniotic fluid, therefore acetminohpen more safe to take