Sigmund Freud: Theory of Psychoanalysis

Prenatal development

begins with fertilization and ends with birth, typically lasting 266-280 days (38-40 weeks). It is divided into three periods: germinal, embryonic, and fetal.

Gestation

period of development between conception and birth.

Gestational age

age of an unborn baby, usually dated from the first day of the expectant mother's last menstrual cycle.

Tender, swollen breasts or nipples

increased production of the female hormones estrogen and progesterone stimulates breast growth to prepare for producing milk (most noticeable in a first pregnancy).

Fatigue; need to take extra naps

woman's heart is pumping harder and faster to produce extra blood to carry nutrients to the fetus. Stepped-up production of hormones takes extra effort. Progesterone depresses central nervous system and may cause sleepiness. Concerns about pregnancy may sap energy.

Slight bleeding or cramping

implantation bleeding may occur about 10 to 14 days after fertilization when the fertilized ovum attaches to the lining of the uterus. Many women also have cramps (similar to menstrual cramps) as the uterus begins to enlarge.

Food cravings

hormonal changes may alter food preferences, especially during the first trimester, when hormones have greatest impact.

Nausea with or without vomiting

rising levels of estrogen produced by placenta and fetus cause stomach to empty more slowly. Also, heightened sense of smell may trigger nausea in response to odors, such as coffee, meat, dairy products, or spicy foods. Morning sickness may begin as early as 2 weeks after conception, but usually around 4 to 8 weeks, and may occur at any time of day.

Frequent urination

enlarging uterus during the first trimester exerts pressure on the bladder.

Frequent, mild headaches

increased blood circulation caused by hormonal changes may bring these on.

Constipation

increase in progesterone may slow digestion, so food passes more slowly through intestinal tract.

Mood swings

flood of hormones early in pregnancy can produce emotional highs and lows.

Faintness and dizziness

lightheaded feeling may be triggered by blood vessel dilation and low blood pressure or by low blood sugar.

Raised basal body temperature

basal body temperature (taken first thing in the morning) normally rises soon after ovulation each month and then drops during menstruation. When menstruation ceases, temperature remains elevated.

Cephalocaudal principle

development proceeds from the head toward the lower part of the trunk. The term comes from Latin and means "head to tail." The embryo's head, brain, and eyes develop earliest and are disproportionately large until the other parts catch up.

Proximodistal principle

development proceeds from parts near the center of the body toward the outer parts. The term comes from Latin and means "near to far." The embryo's head and trunk develop before the limbs, and the arms and legs develop before the fingers and toes.

Germinal period

the period of prenatal development that takes place during the first two weeks after conception. It includes the creation of the zygote, continued cell division, and attachment to the uterine wall. Cell division occurs rapidly through mitosis, and cell differentiation begins around one week after conception. The germinal period ends when the blastocyst attaches to the uterine wall.

Implantation

occurs when the developing organism attaches to the uterine wall, typically 11-15 days after conception.

Zygote

the fertilized egg that is created at the beginning of prenatal development. It undergoes rapid cell division during the germinal period.

Blastocyst

the developing structure that forms during the germinal period and contains an inner mass of cells and an outer layer of cells. The inner mass of cells later develops into the embryo. The outer layer is called the trophoblast.

Trophoblast

the outer layer of cells that develops during the germinal period. It provides nutrition and support for the embryo.

Blastocyst specialization

just one week after conception, the cells of the blastocyst have already begun specializing.

Embryonic period

the period of prenatal development that occurs approximately two to eight weeks after conception. The rate of cell differentiation intensifies, support systems form, and organs begin to appear. It begins as the blastocyst attaches to the uterine wall, with the developing cell mass now referred to as the embryo.

Fertilization

usually occurs in upper third of tube within 24 hours after ovulation.

1 month

growth is more rapid than at any other time in life; the embryo reaches a size 10,000 times greater than the zygote. By the end of the first month it measures about ¼ inch in length. Blood flows through its veins and arteries. It has a minuscule heart that beats 65 times a minute, and the beginning of a brain, kidneys, liver, and digestive tract. The umbilical cord is working.

7 weeks

less than 1 inch long and weighs about ⅐ ounce (half its total body length). Facial parts are developing, with tongue and teeth buds. The arms have hands, fingers, and thumbs, and the legs have knees, ankles, feet, and toes. The fetus has a thin covering of skin. The stomach produces digestive juices; the liver, blood cells; the kidneys remove uric acid from the blood. The skin is now sensitive enough to react to tactile stimulation.

3 months

about 3 inches in length and weighs about 1 ounce. It has fingernails, toenails, eyelids (still closed), vocal cords, lips, and a nose. Its head is still large (about one-third its total length). The arms, legs, and head move, the mouth opens and closes, and the sex is detectable. If its palm is touched, it makes a partial fist; if its lip is touched, it will suck.

4 months

the head is now only one-fourth the total body length, the same proportion it will be at birth. The fetus now measures 8 to 10 inches and weighs about 6 ounces. The placenta is now fully developed. The mother may be able to feel the fetus kicking, a movement known as quickening.

5 months

the fetus, now weighing about 12 ounces to 1 pound and measuring about 1 foot, has definite sleep-wake patterns and a favorite position in the uterus (its lie). It becomes more active: kicking, stretching, squirming, and hiccuping. The sweat and sebaceous glands are functioning. Coarse hair has begun to grow for eyebrows and eyelashes, and a woolly hair called lanugo covers the body.

6 months

the rate of fetal growth has slowed a little; by the end of the sixth month, the fetus is about 14 inches long and weighing 1¼ pounds. It has fat pads under the skin; the eyes open, close, and look in all directions. It can make a fist with a strong grip. A fetus born in the sixth month has only a slight chance of survival because the breathing apparatus has not matured.

7 months

by the end of the seventh month, the fetus, about 16 inches long and weighing 3 to 5 pounds, now has fully developed reflex patterns. It cries, breathes, and swallows, and it may suck its thumb. The lanugo may disappear at this time, or it may remain until shortly after birth. Head hair may continue to grow. The chances that a fetus weighing at least 3½ pounds will survive are fairly good, provided it receives intensive medical attention.

8 months

the 8-month-old fetus is 18 to 20 inches long and weighs between 5 and 7 pounds. Its living quarters are becoming cramped, so its movements are curtailed. During this month and the next, a layer of fat is developing over the fetus's entire body, which will enable it to adjust to varying temperatures outside the womb.

9 months-newborn

about a week before birth, the fetus stops growing, having reached an average weight of about 7½ pounds and a length of about 20 inches, with boys tending to be slightly longer. The reddish color of the skin is fading. At birth, the fetus will have been in the womb for about 266 days, though gestational age is usually estimated at 280 days because most doctors date the pregnancy from the mother's last menstrual period.

First trimester, conception to 4 weeks

less than ⅒ inch long; beginning development of spinal cord, nervous system, gastrointestinal system, heart, and lungs; amniotic sac envelops the preliminary tissues of entire body; is called a "zygote."

First trimester, 8 weeks

about 0.6 inch long; face is forming with rudimentary eyes, ears, mouth, and tooth buds; arms and legs are moving; brain is forming; fetal heartbeat is detectable with ultrasound; is called an "embryo."

First trimester, 12 weeks

about 2 inches long and weighs about 0.5 ounce; fingerprints are present; can move arms, legs, fingers, and toes; can smile, frown, suck, and swallow; sex is distinguishable; can urinate; is called a "fetus."

Second trimester, 16 weeks

about 5 inches long and weighs about 3.5 ounces; heartbeat is strong; skin is thin, transparent; downy hair (lanugo) covers body; fingernails and toenails are forming; has coordinated movements; is able to roll over in amniotic fluid.

Second trimester, 20 weeks

about 6.5 inches long and weighs about 11 ounces; heartbeat is audible with ordinary stethoscope; sucks thumb; hiccups; hair, eyelashes, eyebrows are present.

Second trimester, 24 weeks

about 12 inches long and weighs about 1.3 pounds; skin is wrinkled and covered with protective coating (vernix caseosa); eyes are open; waste matter is collected in bowel; has strong grip.

Third trimester, 28 weeks

about 15 inches long and weighs about 2.3 pounds; is adding body fat; is very active; rudimentary breathing movements are present.

Third trimester, 32 weeks

about 17 inches long and weighs about 4 pounds; has periods of sleep and wakefulness; responds to sounds; may assume the birth position; bones of head are soft and flexible; iron is being stored in liver.

Third trimester, 36 to 38 weeks

about 19 to 20 inches long and weighs 6 to 7½ pounds; skin is less wrinkled; vernix caseosa is thick; lanugo is mostly gone; is less active; is gaining immunities from mother.

Endoderm

inner layer; develops into the digestive and respiratory systems.

Mesoderm

middle layer; develops into the circulatory system, bones, muscles, excretory system, and reproductive system.

Ectoderm

outermost layer; develops into the nervous system and brain, sensory receptors, and parts of the skin such as hair and nails.

Life-support systems

as the embryo's three layers form, life-support systems develop rapidly. They include the amnion, umbilical cord, and placenta. The amnion and umbilical cord develop from the fertilized egg, not the mother's body.

Amnion

a sac containing clear fluid in which the developing embryo floats. The amniotic fluid provides an environment that is temperature and humidity controlled, as well as shockproof.

Umbilical cord

contains two arteries and one vein and connects the baby to the placenta.

Placenta

a disk-shaped group of tissues in which small blood vessels from the mother and offspring intertwine but do not join. Very small molecules such as oxygen, water, salt, and food from the mother's blood can pass to the embryo or fetus. Carbon dioxide and digestive wastes from the offspring's blood can pass back toward the mother.

Placental barrier

virtually any drug or chemical substance the pregnant woman ingests can cross the placenta to some degree, unless it is metabolized or altered during passage, or the molecules are too large to pass through the placental wall.

Ethanol

can cross the human placenta and primarily reflects maternal alcohol use.

Cortisol

the stress hormone cortisol can also cross the placenta.

Organogenesis

the process of organ formation during the first two months of prenatal development. While organs are being formed, they are especially vulnerable to environmental changes.

Fetal period

lasts about seven months and is the prenatal period between two months after conception and birth in typical pregnancies. Growth and development continue rapidly throughout this period.

Brain development

one of the most remarkable aspects of the prenatal period. By birth, babies are estimated to have as many as 20 to 100 billion neurons, or nerve cells, which handle information processing at the cellular level in the brain.

Neural tube

the nervous system begins forming as a long, hollow tube located on the embryo's back. It forms at about 18-24 days after conception and develops from the ectoderm. The tube closes at its top and bottom ends at about 27 days after conception. The nervous system still has a tubular appearance at six weeks after conception.

Anencephaly

occurs when the head end of the neural tube fails to close, causing the highest regions of the brain to fail to develop.

Spina bifida

can result in varying degrees of paralysis of the lower limbs. Individuals with spina bifida usually need assistive devices such as crutches, braces, or wheelchairs.

Neurogenesis

the generation of new neurons. After the neural tube closes, a massive proliferation of new immature neurons begins at about the fifth prenatal week. It continues throughout the remainder of the prenatal period but is largely complete by the end of the fifth month after conception. At the peak, as many as 200,000 neurons can be generated every minute.

Neuronal migration

occurs approximately 6-24 weeks after conception. It involves cells moving outward from their point of origin to their appropriate locations. This process creates the different levels, structures, and regions of the brain. Once a cell reaches its target destination, it must mature and develop a more complex structure.

Neural connectivity

at about the 23rd prenatal week, connections between neurons begin to occur. It is a process that continues after birth.

Teratogen

any agent that can potentially cause a birth defect or negatively alter cognitive and behavioral outcomes. The word comes from the Greek word tera, meaning "monster." Practically every fetus is exposed to at least some teratogens. It can be difficult to determine which teratogen causes a particular problem, and the effects may take a long time to appear. Only about half of all potential effects appear at birth.

Teratology

the field of study that investigates the causes of birth defects.

Psychoactive drugs

It acts on the nervous system to alter states of consciousness, modify perceptions, and change moods.

Fetal alcohol spectrum disorders

They are a cluster of abnormalities and problems that appear in the offspring of mothers who drink alcohol heavily during pregnancy