Fetus

Sounding of the noises of the fetal heart

During the gynaecological examination of the Expectant mother, it is necessary to carry out the sounding of the noises of the fetal heart:

to 12 - 15 weeks of Amenorrhoea (SA): use of a detector with ultrasounds using the Doppler effect;
from 20 - 22 SA: use of a Stethoscope obstétrical (Stethoscope of Plonk).

The basic rate/rhythm ranges between 110 and 160 beats per minute (bpm).

Etymology and pronunciation

The word fetus comes from Latin straws meaning “childbirth, carried the small ones”. The orthography fetus then fetus is secondary in Latin and due to a Hypercorrection, restoring a nonetymological Diphtongue ( straws is in “fertile” connection with fecundus , therefore of a root in - E). However, certain languages, whose French, privileged the faulty orthography.

In French, fetus must decide, straws , and not, fire-keep silent .
Indeed, the binding “œ” decides (E) and not (A) (thus, it is necessary to pronounce edema like édème , esophagus like ésophage , oecumenical like ecumenical , Oedipus like Édipe and even coelacanth like sélacanthe ).

The Human Fetus

The fetal stage begins eight weeks after the fertilization, it follows the embryonic stage. The fetus is much less sensitive to the external aggressions than the embryo (shock, dangerous substance…), although the toxic exposures can cause physiological anomalies or malformations. The fetal growth can end for various reasons: foeticide, abortion (agreed or not), too important shock…

Development

The chronology used below described the specific changes of the anatomy and the physiology of the fetus since the fertilization . It is however advisable to note that the obstetricians often employ the age of gestation which, by convention, precedes two weeks the age of fertilization (or conceptional age). During all this article, except contrary mention, we will measure the age starting from the fertilization.

; 8 weeks (the fetal stage starts):

The risk of loss of the fetus is strongly decreased at the beginning of this stage. This stage, all major structures, including the hands, the feet, the head, the brain, and other bodies are present, but they continue to develop and become increasingly functional. When the fetal stage begins, a fetus measures approximately 30 millimetres length, and its heart beats already. The fetus manages to fold the head, and carries out movements which imply all the body. The brain shows signs of activity as of the 54e day. A digital fingerprint starts to be formed and is a little visible at this stage.

; 8 to 15 weeks:

The fetus continues to move and moves from now on more precisely certain driving bodies such as the arms or the legs, of the movements of hoquet, breathing, stretching and yawn are also observable. These shows of breathings are important and necessary to the good development of its lungs and fulfill this role rather than to bring any quantity of oxygen at this stage. As from the 9th week the fetus can fold its fingers around an object, fold the legs or curve the toes in answer to a contact on the foot to move away some. The face is well formed and has a more human aspect. The eyelids are closed and will still remain it during several months. The differentiation of the genitals male or female becomes marked. " bourgeons" teeth appear, the members continued to grow and are thin, moreover the red globules are produced in the liver. Fine hair - called lanugo - appears on the head. The gastro-intestinal apparatus forms the méconium , first saddles of the fetus. The skin of the fetus is practically transparent. The muscular and osseous fabrics still developed. The first measurable signs of the electroencephalographic activity occur during the 12th week. Towards the end of this stage, the fetus reaches approximately the size of 15 centimetres.

; 16 to 25 weeks:

The lanugo entirely covers the body. The eyebrows, the lashes and the nails (of the hands and the feet) appear. The development of its muscles increased, and of the cells (bags of air) are formed in its lungs. The nervous system from now on is sufficiently developed to control some functions of the body. The Cochlée S are now developed however the sheaths of Myéline in the neurale part of the auditive system will continue to develop up to eighteen months after the birth. The respiratory system developed with a point where it allows the gaseous exchange. Acceleration, the first discernible fetal movements by the mother are often felt during this period. An expectant mother for the first time (i.e. Primiparous) generally feels the fetal movements in the neighborhoods of the 18 and 19th week, whereas a woman having already had a child generally feels the movements about the 16th week. Towards the end of this fifth month, the fetus measures surroundings twenty centimetres.

; 26 to 38 weeks:

The body quantity of greases increases quickly. The lungs are not entirely mature. Connections to the Thalamus, which manages the sensory factors, are formed. The bones are completely mature but are still soft and flexible. Iron, calcium and phosphorus become more abundant. One observes a continuous electroencephalographic activity starting from the 30e week. The nails reach the ends of the fingers. The lanugo starts to disappear except on the arms and the shoulders. The buds of center are present. The hair becomes thicker. The birth is imminent and occurs around the 38e week. The fetus is regarded as come to a end of development between the 35e and 40e week, which means that it is considered ready to live apart from the uterus. It can measure (without anomaly) from 48 to 53 centimetres.

Variation of growth

Viability

Fetal pain

Circulatory system

Postnatal development

Difference with the adult circulatory system

Problems of the development

Fetus and environment

The placental barrrière does not protect the fetus and the embryo from all the pathogenic ones or contaminant S of the environment which is present in the body of the mother, and which one finds in particular in the blood of the Umbilical cord. In 2007, a new study ordered by an ONG north American ( EWG ) sought 413 toxic or undesirable chemical substances in the blood of umbilical cords. 287 were found (200 per baby on average, including 187 famous carcinogens for the man and/or the animal, 217 neurotoxic; 208 being suscepticle to induce malformations with the birth according to the experiments made on the animal. One finds there in particular Insecticide S Organochloré S (for some prohibited since more than 30 years), of PCB, PBDE (retarding of flame), of the Dioxine S, PFC, the Hydrocarbure S, the Plomb, the mercury, etc

Ethical questions

See too

External bonds

Development off the human embryo

Simple: Straws Zh-min-nan: Tea-jî

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