Pregnancy's Progress:

Fetal Development 

 

Pregnancy and fetal development begin at the moment of conception. For the next nine months , your unborn baby will experience numerous basic physical developments. Before coming in the light of earth he/she has been nourished from mother's body and become a little human being from a small embryo of mother's ovum.

 

Some of the basic changes of the baby are summarizes here. 

 

FETAL DEVELOPMENT FIRST TRIMESTER  

(1-13weeks)

This is a period of  rapid growth, from a single cell to an easily recognizable human fetus approximately 3 inches long, comprising billions of cells.

Four weeks: the embryo is just visible

• development of  chorionic villi, from which the placenta is formed

• production of HCG hormone, which prevents menstruation from occurring

Five weeks :beginning of  the embryo’s  nervous system is evident as a ridge of tissue running from top (development of the brain) to  the development of the spinal cord

• initial formation of the heart, with faint beats

Six weeks : the embryo grows to about 1/3 inch

• spinal cord, brain, ears and eyes have started to develop

• internal organs (lungs, digestive system,  kidneys) begin to appear

• tiny buds of  arms and legs take share

Seven weeks : the major organs develop

• distinct facial features appear, with skin covering the eyes

• clearly definable arms and legs, with the emergence of fingers and          toes

• muscles, bones and blood vessels begin  to develop , and the tiny heart    of the embryo beats rapidly, at about 160 beats per minute

Eight weeks : all major organs nearly  formed.

• head is very large in proportion  to the body as rapid brain growth           occurs

• embryo makes slight movements , and is about 3/5 inch long

• amniotic sac fills about 2/3 of the uterus, sealing in the amniotic  fluid,    which surrounds  and protects the unborn infant

12 weeks :  embryo is now called a fetus.

Nine-13 weeks : by 12 weeks the fetus is a recognizable human being

• although gender was determined at conception, the sex  organs now        begin to differentiate into male or  female genitals

• by the end of this trimester, the  fetus is a time but fully formed human    being , about three inches long  and weighing  one ounce 

FETAL DEVELOPMENT SECOND TRIMESTER

(13-26 weeks)

16 weeks : fine, downy hair begins to grow over the delicate  semi – transparent skin   of the fetus

• bone and circulatory growth continues  rapidly; fingernails and toenails     are present 

• external genital organs are fully formed  and sex can be clearly                distinguished

20 weeks : the fetus will swallow amniotic fluid and the kidneys produce fairly  large quantities of  urine, which is excreted  into the amniotic fluid

• scalp hair appears

24weeks : at this stage the fetus is termed viable ( able to survive )and weighs about1 1/2lb

• very little body fat

• skin is wrinkled and covered with  a white cheesy substance called          vernix this protects and  lubricates the  delicate skin

• mother may feel vigorous

 

FETAL DEVELOPMENT THIRD TRIMESTER

(27-40 weeks)

28 weeks: your unborn child will spend the next few weeks  laying down fat under her skin 

• body undergoes rapid growth and size

• hiccupping is common for the baby; you may experience a gently              rhythmic sensation

• lungs are beginning to function

32 weeks :  a baby born  at this stage has a good chance of survival with neonatal care

• baby weighs about 4-4 ½ lb.

32-40 weeks : a great del of fat continues to be laid down

• infant’s lungs have matured significantly in preparation for survival in         the external environment

• vernix is shed

• child is fully developed at this time , with the characteristic features of     the newborn infant