Fetal Milestones
End of 4th Gestational Week
At the end of the fourth week of gestation, the human embryo is a group of rapidly growing cells but does not yet resemble a human being.
• Length: 0.75-1 cm Weight: 400 mg The spinal cord is formed and fused at the midpoint.
: Lateral wings that will co anth fibody ate olided forward
to fuse at the midline.
* The head folds forward and becomes prominent, representing about one-third of the entire structure.
* The back is bent so that the head almost touches the tip of the tail.
* The rudimentary heart appears as a prominent bulge on the anterior surface.
: Arms and legs are budlike structures.
Rudimentary eyes, ears, and nose are discernible.
End of 8th Gestational Week
: Wagth: 2,5 cm (1 in)
Weight: 20 g
* Organogenesis is complete.
* The heart, with a septum and valves, is beating rhythmically.
* Facial features are definitely discernible.
* Arms and legs have developed.
* External genitalia are forming, but sex is not yet distinguishable by simple observation. 'The primitive tail is regressing.
• The abdomen bulges forward because the fetal intestine is An ultraso ad shows a gestational sac, diagnostic of pregnancy (Fig. 9.8).
End of 12th Gestational Week (First Trimester)
• Length: 7-8 cm Weight: 45 g Nail beds are forming on fingers and toes. Spontancous movements are possible, although they are usually too faint to be felt by the mother.
• Some reflexes, such as the Babinski reflex, are present. Bone ossification centers begin to form.
* Tooth buds are present. Sex is distinguishable by outward appearance.
* Urine secretion begins but may not yet be evident in amniotic fluid.
* The heartbeat is audible through Doppler technology.
End of 16th Gestational Week
Length: 10-17 cm
• Weight: 55-120 g Fetal heart sounds are audible by an ordinary stethoscope. Lanugo is well formed. Liver and pancreas are functioning.
: Fives acd pay salare unioric fuid, demonstating an
intact but uncoordinated swallowing reflex; urine is present in amniotic fluid.
• Sex can be determined by ultrasound.
Eyebrows and eyelashes become well defined.
Eyelids, previously fused since the 12th week, now open.
* Pupils are capable of reacting to light.
* When fetuses reach 24 weeks, or 601 g,
they have
achieved a practical low-end age of viability (earliest age at which fetuses could survive if born at that time), if they are cared for after birth in a modern intensive care facility.
• Hearing can be demonstrated by response to sudden sound.
End of 28th Gestational Week
• Length: 35-38 cm
: Weighi do
Weight: 1200 g
begin to mature, and surfactant can be
demonstrated in amniotic fluid.
* Testes begin to descend into the scrotal sac from the lower abdominal cavity.
* The blood vessels of the retina are formed but thin and extremely susceptible to damage from high oxygen concentrations (an important consideration when caring for preterm infants who need oxygen).
End of 32nd Gestational Week
• Length: 38-43 cm
Weight: 1600 g
* Subcutaneous fat begins to be deposited (the former stringy, "little old man" appearance is lost).
* Fetus responds by
movement to sounds outside the
mother's body.
: Arcises, wrex is presen.
Iron stores, which provide iron for the time during which the neonate will ingest only milk after birth, are beginning to be developed.
• Fingernails grow to reach the end of fingertips.
End of 20th Gestational Week
Length: 25 cm
Weight: 223 g
Spontaneous fetal movements can be sensed by the mother.
Antibody production is possible.
The hair forms on the head, extending to include eyebrows.
Meconium is present in the upper intestine.
lation at birth, begins to be formed behind the kidneys, sternum, and posterior neck.
Vernix caseosa begins to form and cover the skin.
Passive antibody transfer from mother to fetus begins.
Definite sleeping and activity patterns are distinguishable (the fetus has
developed biorhythms that will guide
sleep/wake patterns throughout life).
End of 24th Gestational Week (Second Trimester)
• Length: 28-36 cm Weight: 550 g Meconium is present as far as the rectum.
• Ative producion of lung surfactant begins.
End of 36th Gestational Week
: Wage: 1500 270
Weight: 1800-2700 g (5-6 1b)
Body stores of glycogen, iron, carbohydrate, and calcium are deposited.
: Sodional amount subcutaneous a are deposited.
Sole of the foot has only one or two crisscross creases, compared with the full crisscross pattern that will be evident at term.
: Amount of lango begins to diminish.
Most babies turn into a vertex (head down) presentation during this month.
End of 40th Gestational Week (Third Trimester)
Length: 48-52 cm (crown to rump, 35-37 cm)
Weight: 3000 g (7-7.5 lb)
* Fetus kicks actively, hard enough to cause the mother considerable discomfort.
* Fetal hemoglobin begins its conversion to adult hemoglo-bin. The conversion is so rapid that, at birth, about 20% of hemoglobin will be adult in character.
* Vernix caseosa is fully formed.
• Fingernails extend over the fingertips.
• Creases on the soles of the feet cover at least two thirds of the surface.