3. Prenatal Development, Birth, and the Newborn

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3. Prenatal Development, Birth, and the Newborn

• 3.1 From Conception to Birth
• 3.2 Influences on Prenatal Development
• 3.3 Happy Birthday!
• 3.4 The Newborn

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3.1 From Conception to Birth

• Prenatal development averages 38 weeks.
• Period of the Zygote
• Period of the Embryo
• Period of the Fetus

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Period of the Zygote

• An egg enters the fallopian tube 9-16 days into
  the menstrual cycle.
• If the egg is fertilized by a sperm in the
  fallopian tube the cells divide. Within 4-5 days
  the zygote enters the uterus as a ball of cells
  and begins to attach to the wall.
• This period ends after 2 weeks, when the zygote
  is implanted in the wall of the uterus and
  establishes connections to the mothers blood
  vessels.

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Figure 3-1
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Period of the Zygote

• Implantation takes a week to complete and
  triggers hormone changes that prevent
  menstruation.
• A small cluster of cells in the center eventually
  becomes the baby and the layer of cells closest
  to the uterine wall becomes the placenta, a
  structure to exchange food and waste between
  mother and baby.

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Period of the Embryo

• From 3 to 8 weeks after conception the zygote is
  embedded and is called an embryo.
• Three layers of cells form into body parts during
  this period.

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Period of the Embryo

• The outer layer or ectoderm, will become the
  hair, outer skin, and nervous system.
• The middle layer or mesoderm, will form muscles,
  bones, and the circulatory system.
• The inner layer or endoderm, will form the
  digestive system and lungs.
• Cell specialization is now underway.

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Period of the Embryo

• The embryo rests in a sac called the amnion
  filled with amniotic fluid to cushion the embryo
  and maintain its temperature.
• The umbilical cord houses blood vessels that join
  the embryo to the placenta.
• Growth during this period follows two patterns,
  cephalocaudal proximodistal.

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Figure 3-3
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Period of the Fetus

• From 9 weeks after conception to birth During
  this period the fetus increases in size and body
  systems begin to function.
• All brain regions grow, especially the cerebral
  cortex.

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Period of the Fetus

• Age of viability 22 to 28 weeks
• Is the age at which most bodily systems are
  functioning and the fetus has a chance to survive
  if born prematurely.

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Age of Viability

• Babies born this young have trouble breathing
  because their lungs are immature.
• They also have difficulty regulating body
  temperature due to lack of a layer of insulating
  fat.
• During this time, the fetus develops regular
  periods of activity.

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Fetal Behavior

• In addition to fetal activity, the eyes and ears
  respond to stimulation.
• Remarkably, newborns can recognize and will
  respond to sounds heard while in the womb.
• What happened, after birth, when pregnant women
  read The Cat in the Hat to their babies a month
  and a half before birth?

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3.2 Influences on Prenatal Development

• General Risk Factors
• Teratogens Diseases, Drugs, and Environmental
  Hazards
• How Teratogens Influence Prenatal Development
• Prenatal Diagnosis and Treatment

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General Risk Factors

• Nutrition- the mother is the childs only source
  of nutrition so a balanced diet is vital.
• A woman of normal weight should gain between
  25-35 lbs during pregnancy.

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Nutrition

• Proteins, vitamins, and minerals are essential
  for normal prenatal development.
• Folic acid, one of the B Vitamins, is important
  for nervous system development. Inadequate
  consumption of folic acid can result in spina
  bifida, where the embryos neural tube does not
  close properly.

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Nutrition

• When a pregnant woman does not provide adequate
  nutrition, the child may be born prematurely or
  under weight for gestational age. In addition,
  rapid brain growth during later pregnancy could
  be adversely effected.

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Stress

• Will chronic stress impact prenatal development?
• Correlational studies indicate anxiety is related
  to early birth and low birth weight.

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Mothers Age

• Teenagers giving birth are prone to problems with
  pregnancy, labor, and delivery, primarily due to
  lack of good prenatal care. Children of teenage
  mothers generally do less well in school and more
  often have behavioral problems.

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Mothers Age

• The problems of teenage motherhood are incomplete
  education, poverty, and marital difficulties, all
  can affect the babys development.

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Mothers Age

• Older women giving birth was common in the 90s,
  why? However, women in their thirties are no
  more prone to risks during pregnancy, labor, and
  delivery than women in their twenties.
• Women in their forties are more likely to give
  birth to children with Down Syndrome.

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Teratogens Diseases, Drugs, and Environmental
Hazards

• Teratogens are powerful agents that cause
  abnormal fetal development.
• Many diseases cross the placenta directly and
  attack the fetus or are present in the birth
  canal when the baby passes through it..
• Several bacterial and viral infections are
  harmful or fatal to the fetus or embryo.

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Diseases

• Five of the most common are AIDS,
  Cytomegalovirus (a type of herpes), Genital
  Herpes, Rubella, and Syphilis.

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Drugs

• Potentially dangerous drugs are not limited to
  cocaine and heroin but include alcohol, caffeine,
  aspirin, nicotine, and marijuana. Nicotine
  constricts blood vessels and reduces the amount
  of oxygen and nutrients reaching the fetus. Even
  second-hand smoke is harmful to the fetus.

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Drugs

• Pregnant women that consume large quantities of
  alcohol often give birth to babies with Fetal
  Alcohol Syndrome (FAS). These children grow more
  slowly, have heart problems, misshapen faces, are
  mentally retarded and have limited motor skills.
  Three or more ounces of alcohol a day can result
  in FAS. Safe levels of alcohol are impossible to
  guarantee.

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Environmental Hazards

• Environmental hazards are treacherous because
  were often unaware of their presence. Chemicals
  associated with industrial waste are the most
  common and quantities are minute. Known hazards
  are lead, mercury, PCBs (polyclorinated
  biphenyls), X-rays.

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Environmental Hazards

• Prenatal exposure to PCBs and cognitive
  function What was the aim of the study? How
  did the investigators measure the topic? Who
  were the children? What were the results? What
  did the investigators conclude?

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How Teratogens Influence Development

• Not universally harmful. A teratogen can be
  harmful to one species and not to another.
• The impact of harm changes over particular
  structures, at particular times during
  development, and can be different for particular
  animals.

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Prenatal Diagnosis and Treatment

• Diagnosis ultrasound (sound waves to generate a
  picture) and amniocentesis (a needle through the
  mothers abdomen to obtain a sample of amniotic
  fluid at 16 weeks) are common procedures.

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Diagnosis

• Chorionic Villus Sampling is sampling tissue from
  the chorion (part of the placenta) through a
  small tube inserted through the vagina. CVS can
  be done 8 wks after conception.

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Treatment

• Fetal medicine is concerned with treating
  prenatal problems before birth with drugs,
  surgery, or genetic engineering and is considered
  an experimental field.

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3.3 Happy Birthday!

• Labor and Delivery
• Approaches to Childbirth
• Postpartum Depression
• Birth Complications

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Labor and Delivery

• Stage 1 starts when the muscles of the uterus
  contract and ends when the cervix is fully
  enlarged (about 10 cm)
• Stage 2 baby is pushed down the birth canal
• Stage 3 placenta is expelled

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• Approaches to Childbirth First be prepared!
• Where to give birth hospitals, at home, birthing
  centers
• Postpartum Depression 10-15 of mothers have
  persistent (months not weeks) irritability,
  disturbed sleep, and apathy.

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Birth Complications

• Lack of Oxygen (Anoxia) Often leads to surgical
  removal of the fetus (C-section) to prevent
  mental retardation or death.
• Prematurity and Low Birth Weight Prematurity is
  less serious than low birth weight.

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Prematurity

• Prematurity is when infants are born less than 38
  weeks after conception. These infants may lag
  behind in development for a year or two but
  eventually catch-up with other children.

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Low Birth Weight

• Low birth weight or small-for-date infants are
  not as prosperous. Mothers of low birth weight
  babies often smoke, drink, or do not consume
  enough nutrition during pregnancy. Babies
  weighing less than 1500 grams at birth often do
  not survive and usually have impaired cognitive
  function.

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3.4 The Newborn

• Assessing the Newborn
• The Newborns Reflexes
• Newborn States
• Perception and Learning in the Newborn

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• Assessing the newborn The Apgar is a scale to
  assess the newborns health. Five vital signs
  receive scores with a score of 7 or above
  indicating good physical condition. The Neonatal
  Behavioral Assessment Scale (NBAS) evaluates a
  broad range of skills and is a more comprehensive
  assessment of infants.

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Newborns

• Newborns reflexes prepare them to interact with
  the world.
• There are 4 primary newborn states alert
  inactivity, waking activity, crying, and
  sleeping.
• Newborns can perceive their environment and learn
  from it.

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Newborns

• Newborns spend 2-3 hours a day crying and have
  three distinctive types of cries basic cry, mad
  cry, and pain cry.
• Crying is an early attempt to communicate.
• Calming a baby can take some experimentation.

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Newborns

• Infants sleep 16-18 hours a day. As babies get
  older the sleep-wake cycle gets closer to the
  day-night cycle.
• Half of newborns sleep is in REM sleep. Many
  scientists believe REM stimulates the brain but
  REM function is still debated.

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SIDS

• SIDS-a healthy baby dies suddenly for no apparent
  reason. 1 to 3 of every 1000 babies dies from
  SIDS most often between 2 and 4 months of age.
  Contributing factors are Prematurity, low birth
  weight, parents who smoke, sleeping on their
  stomachs, overheating with too much heavy
  clothing or blankets.

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SIDS

• The widely publicized Back to Sleep campaign has
  helped to reduce the incidence of SIDS.