Первый слайд презентации: CRITICAL PERIOD OF FETAL DEVELOPMENT
BY- GARGI KULSHRESTHA
Слайд 2: WHAT IS A CRITICAL PERIOD?
In pregnancy, each part of the baby's body forms at a specific time. During these times, the body can be very sensitive to damage caused by medications, alcohol or other harmful exposures. We call this specific time the “ critical period of development ” for that body part.
The first trimester is the most crucial for a baby's development. During this period, baby's body structure and organ systems develop. Most miscarriages and birth defects occur during this period. Therefore, FIRST TRIMESTER OF PREGNANCY is considered as MOST CRITICAL PERIOD OF FETAL DEVELOPMENT.
Слайд 4: THE FIRST TRIMESTER: FETAL DEVELOPMENT
The most dramatic changes and development happen during the first trimester. During the first eight weeks, a fetus is called an embryo. The embryo develops rapidly and by the end of the first trimester, it becomes a fetus that is fully formed, weighing approximately 0.5 to 1 ounce and measuring, on average, 3 to 4 inches in length.
Слайд 6: BY THE END OF FOUR WEEKS
All major systems and organs begin to form. The embryo looks like a tadpole. The neural tube (which becomes the brain and spinal cord), the digestive system, and the heart and circulatory system begin to form. The development of eyes and ears begins. Tiny limb buds appear, which will develop into arms and legs. The heart starts beating.
Слайд 7: BY THE END OF EIGHT WEEKS
All major body systems continue to develop and function, including the circulatory, nervous, digestive, and urinary systems. The embryo start s taking on a human shape, although the head is larger in proportion to the rest of the body. The mouth develops from tooth buds, which will become baby teeth. The eyes, nose, mouth, and ears become more distinct. The arms and legs can be easily seen. The fingers and toes are still webbed, but can be clearly distinguished. The main organs continue to develop and the baby's heartbeat can be heard. The bones begin to develop and the nose and jaws are rapidly developing. The embryo is in constant motion but cannot be felt by the mother.
Слайд 8: FROM EMBRYO TO FETUS
After 8 weeks, the embryo is now referred to as a fetus, which means offspring. Although the fetus is only 1 to 1.5 inches long at this point, all major organs and systems have been formed.
Слайд 9: DURING WEEKS 9 TO 12
The external genital organs are developed. Fingernails and toenails appear. Eyelids are formed. Fetal movement increases. The arms and legs are fully formed. The voice box (larynx) begins to form in the trachea.
The fetus is most vulnerable during the first 12 weeks. During this period of time, all of the major organs and body systems are forming and can be damaged if the fetus is exposed to drugs, infectious agents, radiation, certain medications, tobacco and toxic substances.
The dark bars on the chart show when each part is most sensitive to harmful exposures and at risk for major birth defects. Birth defects are typically classified as “major” if they cause significant medical problems and need surgery or other treatment to repair. Heart defects, spina bifida, and clubfeet are examples of major birth defects.
The lightly shaded bars show periods when the body parts are still at risk to develop minor birth defects and functional defects. “Minor” birth defects by themselves do not cause significant medical problems and usually do not require treatment or surgery. Minor birth defects can also be variations of normal development. Wide-set eyes and large ears are examples of minor birth defects.
Both major and minor birth defects are physical or structural changes. However, “functional” defects change how a part of the body works without changing its physical structure. Intellectual disability and hearing loss are both examples of functional defects.
The chart also shows the location of the most common birth defects that can occur during each week. In general, major defects of the body and internal organs are more likely to occur between 3 to 12 embryo / fetal weeks. This is the same as 5 to 14 gestational weeks. also referred to as the first trimester. Minor defects and functional defects including those affecting the brain are also able to occur later in pregnancy.