Chapter 3: Prenatal Development and Birth

3 periods of prenatal development

Germinal, Embryonic, and Fetal

Germinal period time frame

First two weeks

Embryonic period time frame

2-8 weeks after conception

Fetal period time frame

2 months after conception until birth

Germinal period

• Creation of the zygote

• Cell division through mitosis

• The zygote develops into a blastocyst (a ball of cells)

• Attachment/implantation to the uterine wall

Embryonic period

• Organs begin to develop (critical period)

• The amnion, umbilical cord, and placenta develop

• Ears, mouth, arm, and leg buds appear

• The neural tube forms

Fetal period

• Continued growth and development

• Chance of survival outside the womb at about 24-25 weeks

• Critical period for brain development

• Hearing begins

• Bones and muscles fully develop

Stages of brain development

• Neurogenesis

• Neural migration

• Neural connectivity

Neurogenesis

• Begins around week 5

• Rapid production of immature neurons

• Mostly complete by the 5th month

• Up to 200,000 nuerons can form per minute

Neural migration

• Occurs about 6-24 weeks after conception

• Neurons move to their proper locations

• Cells then mature and become more complex

Neural connectivity

• Occurs mainly during 2nd and 3rd trimesters

• Neurons rapidly form connections

• Brain functions begin becoming specialized

Factors that affect the influence of teratogens

Dose, genetic susceptibility, and time of exposure

Dose

Higher exposure leads to greater potential effect

Genetic susceptibility

Mother/fetus genetics affect vulnerability

• For example, how a mother metabolizes a particular rug can influence the degree to which the drug’s effects are transmitted to the embryo or fetus

Time of exposure

Exposure to teratogens does more damage when it occurs at some points in development than at others

Damage during the ___ period may even prevent implantation

Germinal

Which period is the most vulnerable to teratogens?

Embryonic

Examples of Teratogens

Drugs, psychological distress, environmental factors, etc.

How can Alcohol impact development

• Heavy use can cause Fetal Alcohol Spectrum Disorders

• Can cause facial, limb, and heart abnormalities

• Learning, attention, language, executive functioning, and intelligence can be affected

How can Stress impact development

• May lead to unhealthy behaviors

• Linked to emotional, behavioral, and psychological difficulties

• Associated with preterm birth

Understand the interaction between the environment and the fetus to determine outcomes on development

• Any disease, drug, or other environmental agent that can harm a developing fetus

• Risk of structural defects greatest in the embryonic period

• Environmental effects are worse during critical periods

• The greater and longer the exposure, the more likely serious damage will occur

• Susceptibility to harm is influenced by genetic makeup

Three main stages of birth

Dilation, delivery, and afterbirth

What hormone causes the uterus to begin contracting during birth?

Oxytocin

What happens during the dilation stage?

Oxytocin causes the uterus to begin contracting, and the contractions cause the cervix to dilate

How much does the cervix dilate to during birth?

10 cm

What causes pain during the dilation stage?

The uterine muscles contract intensely for an extended period of time

Which stage of birth is the longest?

Dilation

How long does dilation usually last?

About 12 hours for the first birth and 6 hours for subsequent births

What happens during the delivery stage?

The stage starts when the baby’s head starts to move through the cervix and the birth canal and ends when the baby completely emerges from the mothers body

How long does the delivery stage last?

About 45 minutes to an hour

What happens duding the afterbirth stage?

The placenta, umbilical cord, and other membranes are detched and expelled.

How long does afterbirth last?

A few minutes to half an hour

Midwives

• Provide healthcare during pregnancy, birth, and the postpartum period

• Can also provide reproductive health information, perform gynecological exams, and refer women to doctors when certain specialized care is warranted

• For low-risk women, midwife-led care is associated with fewer procedures during labor, greater satisfaction, and no adverse outcomes compared with physcianled care

Duolas

• Provide physical, emotional, and educational support before childbirth, during labor, and/or after childbirth

• Doula-assisted mothers are associated with less likely to have a low-birth-weight baby and less likely to experience a birth complication involving themselves or the baby

Natural Childbirth

• The goal is to reduce pain and fear without relying entirely on medicine

• It uses information about childbirth, breathing techniques, relaxation techniques, and partner involvement

What are the factors assessed with the Apgar Scale?

• Appearance (color)

• Pulse rate (heart rate)

• Grimace (reflex irritability)

• Activity (muscle tone)

• Respiration (respiratory effort)

What do the scores for the Apgar Scale indicate?

• An obstetrician or a nurse does the evaluation and gives the newborn a score, or reading, of 0, 1, or 2 on each of the five health signs

• A total score of 7 to 10 indicates that the newborn’s condition is good. A score of 5 indicates there may be developmental difficulties. A score of 3 or below signals an emergency and indicates that the baby might not survive.

What are the three conditions that pose threats to newborns?

Low birth wight, preterm infants, and small for date infants

Low birth weight

Less than 5 pounds 8 ounces

Preterm infants

Born 3 weeks or more before full term

Small for date infants

Weigh less than 90% of all babies of the same age; they may be preterm or full term

Postpartum depression

A condition experienced by women who have such strong feelings of sadness, anxiety, or despair that they have trouble coping with daily tasks during the postpartum period.

Risk factors for postpartum depression

• History of depression

• Depression and anxiety during pregnancy

• Neuroticism

• Low self-esteem

• Postpartum blues

• A poor marital relationship

• Low level of social support

Practices that help prevent postpartum depression

• Practices that support mothers socially, emotionally, and physically

• Ex: help around the house, pampering, limiting responsibilities and daily activities, emphasis on time to recover