Firstborn children are not threatened, because the mother's blood has not had time to produce a large amount of antibodies, but the risk increases with each pregnancy. Regular doctors visits are used to track weight gain, general health, and to check on the status of the cervix and uterus. Dose amount - higher risk of negative effects if large doses over long periods of time Heredity - based on genetic makeup, some people are better than others at withstanding harmful agents Age - if the organism is exposed during a sensitive period of development, the likelier damage is to occur Other negative influences - multiple negative factors can worsen impact of each harmful agent Each prenatal stage has a sensitive period in which development is especially susceptible to damage.
First they go through a phase of rapid multiplication in the number of cells. Fetal alcohol syndrome FAS , identified in 1973, is perhaps one of the best known and best documented outcomes of drinking, affecting approximately one out of every 750 births.
YouTube Video. The results of studies of thousands of pregnancies in the United States and elsewhere, encompassing various ethnic, racial, and cultural groupings, indicate that the fetus and newborn are significantly affected by cigarette smoking during pregnancy.
When the human body is in better condition, it can better fight off diseases, and when struck with illness, it reacts in a more positive fashion.
The fetus' sense of hearing has also begun to function during this period, as evidenced by startled reactions to loud sounds. The Rh-positive factor is an inherited genetically dominant trait in the blood that can result in a dangerous situation for the fetus. The umbilical cord contains three blood vessels through which the embryo's blood circulates to and from the placenta.
Only in circumstances involving an Rh-negative mother and an Rh-positive child does this danger exist. Many diseases are capable of injuring a growing fetus. Women with toxemia frequently give birth to premature babies or to babies smaller than average for their gestational age. Smoking tobacco is also considered a teratogen because nicotine travels through the placenta to the fetus.
Telomerase is the protein responsible for lengthening telomeres and has recently been found to play a variety of roles in keeping the cell healthy and functioning properly.
Every person is made up of cells containing chromosomes, which are the genetic material that determines many things about a person, such as eye and hair color, biological sex, and personality traits. Furthermore, an article appearing in the January 2013 issue of Hypertension found that mice predisposed to hypertension through a maternal low protein diet during pregnancy had higher blood pressure during sympathetic nervous system activation of the cardiovascular system Prenatal Programming of Hypertension Induces Sympathetic Overactivity in Response to Physical Stress , 2013.
It may even suck its thumb. The mouth, nose, eyes, and head are clear and distinct.
Early Adulthood. Other teratogens that affect prenatal development include radiation, pollution, and infectious disease. By the end of the embryo stage many body systems will be in operation, and the embryo will begin to appear human-like. Telomeres may be used as a signal for prenatal stress.