Prenatal Development and Birth

how much does the embryo weigh the 8th week after conception? How much does it move per hour?

At the end of the eighth week after conception (56 days), the embryo weighs just one-thirtieth of an ounce (1 gram) and is about 1 inch ( centimeters) long. It moves frequently, about 150 times per hour,

when does birth occur?

Birth occurs after 12 hours of active labor for first births and 7 hours for subsequent ones

five weeks in the embryonic development

By the fifth week, buds that will become arms and legs emerge. Upper arms and then forearms, palms, and webbed fingers grow. Legs, knees, feet, and webbed toes, in that order, appear a few days later, each with the beginning of a skeleton. Then, 52 and 54 days after conception, respectively, the fingers and toes separate

The average fetus weighs how much in the 3rd trimester and at birth?

The average fetus in the United States gains about pounds (2.1 kilograms) in the third trimester, increasing to about pounds (about 3.4 kilograms) at birth

what is the central nervous system?

The central nervous system is the first body system to begin development. The embryonic stage starts with the primitive streak, which becomes the neural tube even before the facial features are formed and the first pulsating blood vessel appears.

embryonic period

The stage of prenatal development from approximately the third week through the eighth week after conception, during which the basic forms of all body structures, including internal organs, develop.

how many neurons do we have at birth?

86 billion neurons at birth

Doulas

A caregiver who provides continuous physical, emotional, and educational support for the mother before, during, and after childbirth.

Vulnerability During The Embryonic Period

About 20 percent of all embryos are aborted spontaneously. This is usually called an early miscarriage, a term that falsely implies something wrong with the woman. In fact the most common reason for a spontaneous abortion is a chromosomal abnormality.

how does labor occur?

About 38 weeks (266 days) after conception, the fetal brain signals massive increases in the hormone oxytocin to start labor.

Vulnerability During The Fetal Period

About 5 percent of all fetuses are aborted spontaneously before viability at 22 weeks or are stillborn, defined as born dead after 22 weeks. This is much more common in poor nations.

two weeks after conception in the embryonic development

About two weeks after conception, a thin line called the primitive streak appears down the middle of the embryo; it forms the neural tube, which develops into the central nervous system, that is, the brain and spinal column. Soon the head appears, as eyes, ears, nose, and mouth start to form and a minuscule blood vessel that will become the heart begins to pulsate.

what are the cons of c sections?

After a c-section, breast-feeding is harder and medical complications more likely. Babies born via c-section are more likely to develop asthma or become obese as children One reason: Vaginal deliveries provide newborns with beneficial microbiomes

How do we develop cells by the 3rd week after conception

Already by the third week after conception some cells specialize to become neural progenitor cells, which duplicate and multiply many times until some of them create neurons (brain cells). Neurons do not duplicate but may endure lifelong. Those early neurons migrate to a particular part of the brain (brainstem, cerebellum, hypothalamus, visual cortex, and so on) and specialize.

Due date:

Although a specific due date based on the LMP is calculated, only 5 percent of babies are born on that exact day. Babies born between two weeks before and one week after that date are considered full term. [This is recent; until 2012, three weeks before and two weeks after were considered full term.] Because of increased risks for postmature babies, labor is often induced if the baby has not arrived a week after the due date.

Vulnerability During The Germinal Period

An estimated 65 percent of all zygotes do not grow or implant properly and thus do not survive the germinal period.

how does the embryo develop it's sex?

At the end of the embryonic period, hormonal and genetic influences typically cause one or the other to shrink, and then ovaries or testes, and a vagina or penis, grow from that omnipotent gonad

Birth

Because of all these factors, only about 27 percent of all zygotes grow and survive to become living newborn babies.

8th week of embryonic development

By eight weeks post conception, the developing embryo has all of the organs and body parts of a human being, including elbows and knees.

neurogenesis

By mid-pregnancy, in neurogenesis, the brain has developed billions of neurons, and folding allows the cortex to be larger and more complex than the brains of other animals

how much does a fetus weigh

Early growth is rapid. By three months, the fetus weighs about 3 ounces (87 grams) and is about 3 inches (7.5 centimeters) long

proximodistal sequence- How many layers of the cortex is produced?

Following the proximodistal (near-to-far) sequence, the six layers of the cortex are produced, with the bottom (sixth) layer first and then each new layer above the previous one so that the top, outer layer is the last to form. Similarly, the brainstem above the back of the neck, then the midbrain, and finally the forebrain develop and connect.

Length of pregnancy:

Full-term pregnancies last 266 days, or 38 weeks, or 9 months. If the LMP is used as the starting time, pregnancy lasts 40 weeks, sometimes expressed as 10 lunar months. (A lunar month is 28 days long.)

Fontanels

Gaps between a baby's skull that slowly close up during the first 18 months of life Preterm babies have larger fontanels, making them vulnerable to brain damage

Cephalocaudal

Growth and development that occurs from the head down.

Proximodistal

Growth or development that occurs from the center or core in an outward direction.

how does a premature baby recognize its mother?

If a baby is born prematurely, impairments are more common in movement, intelligence, and/or vision than in hearing

what systems develop In the final three prenatal months?

In the final three prenatal months, the neurological, respiratory, and cardiovascular systems all develop. The lungs expand and contract, and breathing muscles strengthen as the fetus swallows and spits out amniotic fluid. The various lobes and areas of the brain are also established

What makes prenatal brain development a particularly complex area of study?

In the first part, basic structures are formed, including the limbic system (for emotions), the prefrontal cortex (for analysis), and the six layers of the cortex (for conscious awareness). Impairments in any of these structures affect the mind and behavior lifelong.

Trimesters:

Instead of germinal period, embryonic period, and fetal period, as used in this text, some writers divide pregnancy into three-month periods called trimesters. Months 1, 2, and 3 are the first trimester; months 4, 5, and 6, the second trimester; and months 7, 8, and 9, the third trimester.

Neurological Plasticity

Neurological plasticity allows the fetus to recognize the voices of familiar people by the sixth month after conception

The Newborn's First Minutes

Newborns usually breathe and cry on their own. The first breaths of air bring oxygen to the lungs and blood, and the infant's color changes from bluish to reddish. ("Reddish" refers to blood color, visible beneath the skin, and applies to newborns of all skin tones.) Eyes open wide; tiny fingers grab; even tinier toes stretch and retract. Usually full-term babies are instantly, zestfully, ready for life.

what helps the brain prevent brain bleeds?

One critical development is thickening of the membranes and bones covering the brain. This helps prevent "brain bleeds,"

Beginning of pregnancy:

Sometimes pregnancy is said to begin at conception, which is the start of gestational age. However, the organism does not become an embryo until about two weeks later, and pregnancy does not affect the woman (and is not confirmed by blood or urine testing) until implantation, so some do not consider the woman pregnant until then. On the other hand, some obstetricians and publications count from the woman's last menstrual period (LMP), usually about 14 days before conception.

when does a baby recognize the mother?

That phenomenal accomplishment (recognizing Mother) occurs within a day or two after birth.

Apgar scale

The APGAR score is an assessment tool used by doctors and nurses to determine whether a newborn requires any medical intervention. It tests five specific criteria of health, and the medical professional assigns a score of 0, 1, or 2 for each category. A perfect score of 10 is rare—most babies will show some minor deficits at the 1-minute mark, and many will still lose points at the 5-minute mark. color, heart rate, cry, muscle tone, and breathing. Nurses could use the scale and sound the alarm immediately if the score was 6 or lower.

age of viability

The age (about 22 weeks after conception) at which a fetus might survive outside the mother's uterus if specialized medical care is available. Every day of prenatal life within the uterus increases viability. If birth occurs before 22 weeks, death is certain because advanced technology cannot maintain life without some brain response.

germinal period

The first two weeks of prenatal development after conception, characterized by rapid cell division and the beginning of cell differentiation.

what forms first and last By eight weeks post conception

The head forms first and the extremities last. This directional pattern continues until puberty, when it reverses.

fetal period

The stage of prenatal development from the ninth week after conception until birth, during which the fetus gains about 7 pounds (more than 3,000 grams) and organs become more mature, gradually able to function on their own.

Birth Positions

Women's birthing positions vary — sitting, squatting, lying down. Some women labor in a tub of warm water, which helps the woman relax (the fetus continues to get oxygen via the umbilical cord)

how does existing neurons begin to be affected by the environment?

if the mother is worried, sleeps fitfully, and/or is addicted to drugs, her newborn might have the same problems in the early weeks after birth. The fetal brain is responsive to many signals from maternal actions, and that can affect the future child's social development

Hippocampus function

learning and memory reveals an explosion of new cells during the fourth prenatal month

why might we need to do a c section

long active labor (more than 24 hours), a narrow pelvis, a large fetus, and advanced maternal age are all conditions that suggest surgery. However, none of these requires a c-section.

Apoptosis

programmed cell death It is apparent that programmed cell death is widespread in prenatal development, and the effects may be transmitted from one generation to the next One estimate finds that almost half of all brain cells are gone before birth

synchrony

simultaneous action, development, or occurrence.

why is the environment more crucial for brain development?

the environment becomes more crucial, as the brain of the future person is affected by the prenatal environment, such as maternal stress, nutrition, patterns of sleep, and exercise.

cesarean sections (c-sections)

when the fetus is removed though incision in the mother's abdomen instead of being pushed by contractions through the vagina

epidural

which is an injection in the spine to stop sensation in the lower body while allowing the birthing woman to be awake. Opioids and epidurals increase the rate of cesarean sections and decrease the rate of breast-feeding