What are the three stages of pregnancy, and what are the major developmental changes in each stage?
Pregnancy is divided into the germinal period, the embryonic period, and the fetal period. During the germinal period, the zygote divides and multiplies until it becomes a blastocyst. The outer shell becomes the placenta, which implants in the uterine lin
What usually occurs in the first few minutes of a newborn's life?
The Apgar test is administered one minute after delivery to assess five vital signs: color, heart rate, cry, muscle tone, and breathing on a scale of 0-2. The test is re-administered five minutes after birth.
What factors determine whether a potentially harmful substance or circumstance will actually have detrimental effects on the developing fetus? What are the causes and consequences of low birth weight?
The timing of exposure, the level of exposure, and genetic vulnerability determine the effects of teratogens. If the exposure occurs during a critical period, the level of exposure exceeds the threshold level, or the fetus has a genetic vulnerability, the
What kinds of changes does the birth of a child cause in family relationships, and what can couples do to help ensure they adjust to these changes in ways that are best for the child?
A new baby becomes a third person in the parents' relationship, and the parents must adjust to that. By building a parental alliance in which both parents commit to cooperate in raising their child, the couple can work together to protect their relationsh
germinal period
The first two weeks of prenatal development after conception, characterized by rapid cell division and the beginning of cell differentiation.
embryonic period
The stage of prenatal development from approximately the third through the eighth week after conception, during which the basic forms of all body structures, including internal organs, develop.
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.
implantation
The process, beginning about 10 days after conception, in which the developing organism burrows into the placenta that lines the uterus, where it can be nourished and protected as it continues to develop.
The Germinal Period Vulnerability During Prenatal Development
An estimated 60 percent of all zygotes do not grow or implant properly and thus do not survive the germinal period. Many of these organisms are abnormal; few women realize they were pregnant.
The Embryonic Period Vulnerability During Prenatal Development
About 20 percent of all embryos are aborted spontaneously, most often because of chromosomal abnormalities. This is usually called an early miscarriage.
The Fetal Period Vulnerability During Prenatal Development
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
Birth Vulnerability During Prenatal Development
Because of all these factors, only about 31 percent of all zygotes grow and survive to become living newborn babies. Age is crucial. One estimate is that less than 3 percent of all conceptions after age 40 result in live births.
embryo
The name for a developing human organism from about the third through the eighth week after conception.
fetus
The name for a developing human organism from the start of the ninth week after conception until birth
ultrasound
An image of a fetus (or an internal organ) produced by using high-frequency sound waves. (Also called sonogram.)
Only one of the 46 human chromosomes determines sex, and the genitals develop last in the prenatal sequence, suggesting that dramatic male-female differences are cultural. On the other hand, several sex differences develop before birth.
Many people believe that the differences between the sexes are sociocultural, not biological. Is there any prenatal support for that view?
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.
Apgar scale
A quick assessment of a newborn's health. The baby's color, heart rate, reflexes, muscle tone, and respiratory effort are given a score of 0, 1, or 2 twice�at one minute and five minutes after birth�and each time the total of all five scores is compared w
cesarean section (c-section)
A surgical birth, in which incisions through the mother's abdomen and uterus allow the fetus to be removed quickly, instead of being delivered through the vagina. (Also called simply section.)
Yes, some people are much more likely to want nature to take its course. However, personal experience often trumps political attitudes about birth and death; several of those who advocate hospital births are also in favor of spending one's final days at h
Do people's attitudes about medical intervention at birth reflect their attitudes about medicine at other points in their life span, in such areas as assisted reproductive technology (ART), immunization, and life support?
doula
A woman who helps with the birth process. Traditionally in Latin America, a doula was the only professional who attended childbirth. Now doulas are likely to arrive at the woman's home during early labor and later work alongside a hospital's staff.
teratogen
An agent or condition, including viruses, drugs, and chemicals, that can impair prenatal development and result in birth defects or even death.
behavioral teratogens
Agents and conditions that can harm the prenatal brain, impairing the future child's intellectual and emotional functioning.
Some laws punish women who jeopardize the health of their fetuses, but a developmental view would consider the micro-, exo-, and macrosystems.
How much protection, if any, should the legal system provide for fetuses? Should alcoholic women who are pregnant be jailed to prevent them from drinking? What about people who enable them to drink, such as their partners, their parents, bar owners, and b
threshold effect
In prenatal development, when a teratogen is relatively harmless in small doses but becomes harmful once exposure reaches a certain level (the threshold).
fetal alcohol syndrome (FAS)
A cluster of birth defects, including abnormal facial characteristics, slow physical growth, and reduced intellectual ability, that may occur in the fetus of a woman who drinks alcohol while pregnant.
seful, yes; optimal, no. Some essential vitamins are missing (too expensive), and individual nutritional needs differ, depending on age, sex, health, genes, and eating habits. The reduction in neural-tube defects is good, but many women don't eat cereal o
Is it beneficial that most breakfast cereals are fortified with vitamins and minerals?
Testing and then treatment are useful at any time because women who know they are HIV-positive are more likely to get treatment, reduce the risk of transmission, or avoid pregnancy. If pregnancy does occur, early diagnosis is best. Getting tested after bi
When is it most important to convince women to be tested for HIV: before pregnancy, after conception, or immediately after birth?
false positive
The result of a laboratory test that reports something as true when in fact it is not true. This can occur for pregnancy tests, when a woman might not be pregnant even though the test says she is, or during pregnancy when a problem is reported that actual
low birthweight (LBW)
A body weight at birth of less than 5� pounds (2,500 grams).
very low birthweight (VLBW)
A body weight at birth of less than 3 pounds, 5 ounces (1,500 grams).
extremely low birthweight (ELBW)
A body weight at birth of less than 2 pounds, 3 ounces (1,000 grams).
preterm
A birth that occurs 3 or more weeks before the full 38 weeks of the typical pregnancy�that is, at 35 or fewer weeks after conception.
small for gestational age (SGA)
A term for a baby whose birthweight is significantly lower than expected, given the time since conception. For example, a 5-pound (2,265-gram) newborn is considered SGA if born on time but not SGA if born two months early. (Also called small-for-dates.)
cerebral palsy
A disorder that results from damage to the brain's motor centers. People with cerebral palsy have difficulty with muscle control, so their speech and/or body movements are impaired.
anoxia
A lack of oxygen that, if prolonged, can cause brain damage or death.
Brazelton Neonatal Behavioral Assessment Scale (NBAS)
A test often administered to newborns that measures responsiveness and records 46 behaviors, including 20 reflexes.
reflex
An unlearned, involuntary action or movement in response to a stimulus. A reflex occurs without conscious thought.
Response for Scientists: Animal research should not, by itself, confirm an assertion that has popular appeal but no scientific evidence. This occurred in the social construction that physical contact was crucial for parent-infant bonding.
Research with animals can benefit people, but it is sometimes wrongly used to support conclusions about people. When does that happen?
Response for Nurses in Obstetrics: Usually not, unless he is experienced, well taught, or has expert guidance. But his presence provides emotional support for the woman, which makes the birth process easier and healthier for mother and baby.
Especially for Nurses in Obstetrics Can the father be of any practical help in the birth process?
couvade
Symptoms of pregnancy and birth experienced by fathers.
postpartum depression
A new mother's feelings of inadequacy and sadness in the days and weeks after giving birth.
parental alliance
Cooperation between a mother and a father based on their mutual commitment to their children. In a parental alliance, the parents support each other in their shared parental roles.
parent-infant bond
The strong, loving connection that forms as parents hold, examine, and feed their newborn.
kangaroo care
A form of newborn care in which mothers (and sometimes fathers) rest their babies on their naked chests, like kangaroo mothers that carry their immature newborns in a pouch on their abdomen.