Fetal development

From Conception to Birth Period of the Zygote Period of the Embryo Period of the Fetus

Period of the Zygote Begins when egg is fertilized in the fallopian tube. Period of rapid cell division Ends 2 weeks later when the zygote is implanted in the wall of the uterus

Period of the Zygote

Period of the Embryo From 3 to 8 weeks after conception Body parts are formed during this period Umbilical cord joins embryo to placenta

Period of the Fetus From 9 weeks after conception to birth Age of viability: 22 to 28 weeks (depend up on the country policy& wt. of the fetus)

Fetal development organ system develop from the 3 primary germ layers

First 8 weeks*

12 – 24 weeks

4 months

20 weeks A protective coating called vernix caseosa begins to form on baby's skin. By the end of this month, your baby will be nearly 8 inches long and weigh almost a pound.

28- 40 weeks

Cardiovascular System Is the first system to function Blood vessels formation begins early in the 3rd week. Heart cell starts to beat by the end of the 3rd week.

Fetal Circulation

Systems development Respiratory system Hematopoietic System Formation of RBCs starts at 3 weeks in yolk sac, then in liver at 6 weeks, then in spleen, lymph nodes, & bone marrow. Respiratory system Fetal lungs don’t function until after delivery Production of surfactant starts at 24 weeks.

Systems development Renal system Neurologic System kidneys appear in the 5th week. Urine is excreted into and mixes with the amniotic fluid Neurologic System Start to develop from ectoderm at week 3 Continue to develop after birth Affected by maternal anemia and nutrition and other factors (disease, trauma)

Gastrointestinal system forms during the 4th week fetus begins to swallow amniotic fluid during second trimester. Receives nutrients from mother. Secretes his own insulin and synthesize glycogen. Meconium: is a sterile, dark greenish brown, semisolid residue of bile and embryonic secretions plus cellular waste (epithelial tissue) and hair swallowed in utero. presence of meconium in amniotic fluid before delivery usually indicates fetal hypoxia

Hepatic system begins to function around 4th week Hematopoiesis starts at about the 6th week Metabolic and glycogen store organ, secretes bile. Full liver function is not achieved well until after delivery

Endocrine system The fetal adrenal cortex produces cortisol, which may be important in the initiation of labor. The thyroid gland develops by the 4th week, it can synthesize thyroxin. Island of Langerhans are developed by the 12th week, and insulin can be extracted from the pancreas by week 20.

Reproductive system By the end of the 9th week, male and female external genitalia appear somewhat similar. At the 12th week, the external genitalia are well developed enough to be easily distinguished. The fetal ovary has many primordial follicles and produces small but increasing amounts of estrogen. Withdrawal bleeding follows rapid drop of maternal estrogen following birth. Estrogen passed to fetus causes enlargement of breast in both male and female infants

Musculoskeletal system Bones and muscles are developed from mesoderm by 4th week. Muscle contract spontaneously by 7th week. Integumentary system Skin derives from ectoderm at 4th week. By 16th week, hand and foot prints are formed. Lanugo hair appears at 12 week on the eye brows and upper lip and covers the body by 20th week. Immunologic system During third trimester, albumin and globulin are present in the fetus. The only immunoglobulin that crosses the placenta is IgG (passive acquired immunity). The fetus produces IgM by the end of first trimester. IgA is not produced by the fetus, but it is gained from colostrums.

Factors affect fetal Development General Risk Factors Teratogens: Diseases, Drugs, and Environmental Hazards Torch infections

General Risk Factors Nutrition: adequate amount of food, protein, vitamins, & minerals Stress: decreases oxygen to fetus and weakens mother’s immune system Mother’s Age: neither too young, nor too old

TORCH INFECTIONS TORCH infections are a group of agents that can infect the fetus or newborn. These include Toxoplasmosis, Other infections, Rubella virus, Cytomegalovirus, and the Herpes simplex virus. Nursing Role At the initial prenatal visit, the nurse performs an assessment that includes careful consideration of cultural, emotional, physical, and physiological factors that may signal a need for genetics counseling and comprehensive fetal evaluation.

Teratogens: Diseases, Drugs, and Environmental Hazards Many diseases pass through the placenta directly and attack the fetus Potentially dangerous drugs not limited to cocaine but include alcohol and caffeine Environmental hazards are treacherous because we’re often unaware of their presence

Effects of Teratogens

Prenatal Diagnosis and Treatment Diagnosis: ultrasound, amniocentesis, and chorionic villus sampling can detect physical deformities and genetic disorders.

Prenatal Diagnosis Amniocentesis late Dx Chorionic Villus Sampling early Dx

Multifetal Pregnancy Monozygotic (identical) twins develop from one fertilized oocyte (zygote) that divides into equal halves during an early cleavage phase (series of mitotic cell divisions) of Development. This type of twinning occurs in approximately 1 of 250 live births (Benirschke, 2004). Monozygotic twins are genetically identical, always the same gender, and very similar in physical appearance

Dizygotic (fraternal) twins develop from two zygotes and may be the same or different genders. Dizygotic twins are no more genetically similar than other siblings born to the same parents Triplets may result from the division of a single zygote into three zygotes (one original fertilized egg), or from the division of one zygote (identical twins are formed) plus another zygote (a total of two original fertilized eggs), or from three different zygotes (a total of three original

Happy Birthday!!! THANKS