Placenta Structure and Function The placenta serves as an interface between the mother and the developing fetus and has three main jobs: Attach the fetus to the uterine wall. Provide nutrients to the fetus. Allow the fetus to transfer waste products to the mother's blood.
What is the embryonic stage? The embryonic stage of gestation is the period after implantation, during which all of the major organs and structures within the growing mammal are formed. Once the embryo is fully formed, it expands, grows, and continues to develop in what is known as the fetal development stage. What happens the first 2 weeks of pregnancy? At 2 weeks pregnant, symptoms of ovulation can clue you in on the best time to have sex and hopefully conceive a baby.
Your cervical mucus becomes thin, clear and stringy, like egg whites, as you near ovulation. What week is most critical in pregnancy?
First Trimester 0 to 13 Weeks The first trimester is the most crucial to your baby's development. During this period, your baby's body structure and organ systems develop. Most miscarriages and birth defects occur during this period. Which stage of pregnancy are the major organs developing? Seven weeks: The major organs develop. Distinct facial features appear with skin covering the eyes.
There are now clearly definable arms and legs with the emergence of developing fingers and toes. The muscles, bones and blood vessels begin to develop. What are the three prenatal stages of development? Development happens quickly during the prenatal period, which is the time between conception and birth. This period is generally divided into three stages: the germinal stage, the embryonic stage, and the fetal stage.
There is no acceptable safe limit for alcohol use during pregnancy, but binge drinking 5 or more drinks on a single occasion or having 7 or more drinks during a single week places a child at particularly high risk. In extreme cases, alcohol consumption can lead to fetal death, but more frequently it can result in fetal alcohol spectrum disorders FASD. This terminology is now used when looking at the effects of exposure and replaces the term fetal alcohol syndrome.
It is preferred because it recognizes that symptoms occur on a spectrum and that all individuals do not have the same characteristics. Children with FASD share certain physical features such as flattened noses, small eye openings, small heads, intellectual developmental delays, and behavioral problems.
ARBD include kidney, bone and heart problems. Several medical experts debunk common myths about the safety of drinking alcohol during pregnancy.
Smoking is also considered a teratogen because nicotine travels through the placenta to the fetus. When the mother smokes, the developing baby experiences a reduction in blood oxygen levels. Tobacco use during pregnancy has been associated with low birth weight, placenta previa, birth defects, preterm delivery, fetal growth restriction, and sudden infant death syndrome. Smoking in the month before getting pregnant and throughout pregnancy increases the chances of these risks.
Quitting smoking before getting pregnant is best. However, for women who are already pregnant, quitting as early as possible can still help protect against some health problems for the mother and baby. Prescription, over-the-counter, or recreational drugs can have serious teratogenic effects. In general, if medication is required, the lowest dose possible should be used. Combination drug therapies and first trimester exposures should be avoided.
Almost three percent of pregnant women use illicit drugs such as marijuana, cocaine, Ecstasy and other amphetamines, and heroin. These drugs can cause low birth-weight, withdrawal symptoms, birth defects, or learning or behavioral problems. Babies born with a heroin addiction need heroin just like an adult addict.
The child will need to be gradually weaned from the heroin under medical supervision; otherwise, the child could have seizures and die.
Environmental chemicals can include an exposure to a wide array of agents including pollution, organic mercury compounds, herbicides, and industrial solvents. Some environmental pollutants of major concern include lead poisoning, which is connected with low birth weight and slowed neurological development. Children who live in older housing in which lead-based paints have been used have been known to eat peeling paint chips thus being exposed to lead.
The chemicals in certain herbicides are also potentially damaging. Radiation is another environmental hazard that a pregnant woman must be aware of. If a mother is exposed to radiation, particularly during the first three months of pregnancy, the child may suffer some congenital deformities. There is also an increased risk of miscarriage and stillbirth.
Mercury leads to physical deformities and intellectual disabilities Dietrich, Sexually transmitted infections STIs can complicate pregnancy and may have serious effects on both the mother and the developing baby.
Most prenatal care today includes testing for STIs, and early detection is important. STIs, such as chlamydia, gonorrhea, syphilis, trichomoniasis and bacterial vaginosis can all be treated and cured with antibiotics that are safe to take during pregnancy. However, in some cases these infections can be treated with antiviral medications or other preventive measures can be taken to reduce the risk of passing the infection to the baby.
Maternal illnesses increase the chance that a baby will be born with a birth defect or have a chronic health problem. Some of the diseases that are known to potentially have an adverse effect on the fetus include: diabetes, cytomegalovirus, toxoplasmosis, Rubella, varicella, hypothyroidism, and Strep B.
If the mother contracts Rubella during the first three months of pregnancy, damage can occur in the eyes, ears, heart, or brain of the unborn child. On a positive note, Rubella has been nearly eliminated in the industrial world due to the vaccine created in Diagnosing these diseases early and receiving appropriate medical care can help improve the outcomes.
Routine prenatal care now includes screening for gestational diabetes and Strep B. Because of a link in blood supply between a mother and fetus, it has been found that stress can leave lasting effects on a developing fetus, even before a child is born. The best-studied outcomes of fetal exposure to maternal prenatal stress are preterm birth and low birth weight. Furthermore, maternal prenatal stress has been associated with a higher risk for a variety of immune and metabolic changes in the child such as asthma, allergic disorders, cardiovascular diseases, hypertension, hyperlipidemia, diabetes, and obesity.
There are several considerations in determining the type and amount of damage that might result from exposure to a particular teratogen Berger, These include:. Figure 6. Critical Periods of Prenatal Development. This image summarizes the three developmental periods in prenatal development.
The blue images indicate where major development is happening and the aqua indicate where refinement is happening. As shown, the majority of organs are particularly susceptible during the embryonic period. The central nervous system still continues to develop in major ways through the fetal period as well. Did you know that pregnant women can improve outcomes for themselves and their babies through a balanced diet and adequate exercise?
Click through this interactive to learn more about the importance of maternal health. Figure 7. Pregnancy affects women in different ways; some notice few adverse side effects, while others feel high levels of discomfort, or develop more serious complications.
There are a number of common side effects of pregnancy. Not everyone experiences all of these nor do women experience them to the same degree. These side effects include nausea particularly during the first months of pregnancy as a result of higher levels of estrogen in the system , heartburn, gas, hemorrhoids, backache, leg cramps, insomnia, constipation, shortness of breath or varicose veins as a result of carrying a heavy load on the abdomen.
What is the cure? The following are some serious complications of pregnancy which can pose health risks to mother and child and that often require special care. Maternal mortality is unacceptably high. About women die from pregnancy or childbirth-related complications around the world every day. It was estimated that in , roughly , women died during and following pregnancy and childbirth. Almost all of these deaths occurred in low-resource settings, and most could have been prevented.
The high number of maternal deaths in some areas of the world reflects inequities in access to health services and highlights the gap between rich and poor. This newborn baby is just starting out in life. They have their whole life ahead of them! While most of their life is still ahead of them — including life stages of infancy, childhood, adolescence, and adulthood — this newborn baby is not just starting out in life.
They are already nine months old, and what happened to them during those nine months will help shape the rest of their life. Some of the shortest — but most important — life stages occur before birth. These stages include the germinal, embryonic, and fetal stages. This concept focuses on the earliest of all human life stages: the germinal stage.
The germinal stage of development is the first and shortest of the stages of the human lifespan. The germinal stage lasts a total of eight to nine days. It begins in a Fallopian tube when an ovum is fertilized by a sperm to form a zygote day 0. The germinal stage continues as the zygote undergoes several initial cell divisions to form a solid ball of cells called a morula days It then continues as the morula undergoes additional changes to become a hollow ball of cells called a blastocyst days The germinal stage ends when the blastocyst implants in the endometrium of the uterus days In the germinal stage, however, nutrients must be obtained from cell cytoplasm or secretions in the Fallopian tube or uterus.
The germinal stage involves several different processes that change an egg and sperm first into a zygote, and then into an embryo. The processes include fertilization, cleavage, blastulation, and implantation. Many sperm travel towards the egg due to chemical attraction. However, only one sperm will succeed in fertilizing the ovum egg , by penetrating its cell membrane and depositing the genetic material into the egg, where the two nuclei fuse.
The fertilized ovum zygote immediately becomes resistant to penetration by any other sperm arriving later. After fertilization occurs, the zygote remains in the fallopian tube for about 72 hours, and during this time it develops rapidly. By the second day after fertilization, the single-celled zygote undergoes mitosis to form two daughter cells. Mitosis continues to take place every 12 to 24 hours to produce the first four cells, then eight, and as many as sixteen cells by day 4.
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