Fetal Development Overview

Questions and Answers

What proportion of the crown-rump length (CRL) does the head constitute at the beginning of the third month?

Two thirds

One quarter

One half (correct)

One third

By the end of the fifth month, what proportion of the crown-heel length (CHL) does the head occupy?

Three quarters

One quarter

One half

One third (correct)

During which week does the fetal period begin?

11th week

7th week

9th week (correct)

13th week

What is the expected maximum crown-rump length (CRL) for a full-term baby by 37-38 weeks?

36 cm Signup and view all the answers

What happens to the growth rate of the head compared to the body as the fetus matures?

The body growth accelerates while head growth slows Signup and view all the answers

What is the primary function of the placenta?

Exchange of nutrients and waste Signup and view all the answers

How is crown-heel length (CHL) defined?

From the vertex of skull to the heel Signup and view all the answers

What is the expected developmental change in the head size from the third month to birth?

Decrease in size relative to body size Signup and view all the answers

What is the range for crown-heel length (CHL) at 9 weeks gestation?

Up to 51 cm Signup and view all the answers

During which months is growth in length particularly striking for a fetus?

3rd, 4th, and 5th months Signup and view all the answers

How is the length of pregnancy typically calculated?

266 days after the onset of the last normal menstrual period Signup and view all the answers

When is the increase in weight during pregnancy most noticeable?

During the last 2 months of gestation Signup and view all the answers

What accurately describes the chorion in a 9-week fetus?

Has both chorion frondosum and chorion laeve Signup and view all the answers

What structure is involved in the herniation of intestinal loops in a 9-week fetus?

Umbilical cord Signup and view all the answers

How is the age of a fetus typically expressed?

In calendar months or weeks after fertilization Signup and view all the answers

Which statement about fetal development is true at 9 weeks?

The head is proportionately larger than the rest of the body. Signup and view all the answers

What components contribute to the fetal side of the placenta?

Trophoblast and extraembryonic mesoderm Signup and view all the answers

Which measurement is NOT typically used to determine fetal size?

Weight of newborn Signup and view all the answers

What is the average weight range for a newborn?

2,500-4,000g Signup and view all the answers

Which layer of the placenta is specifically formed from the uterine endometrium?

Decidua basalis Signup and view all the answers

Which structure connects the fetus to the placenta?

Umbilical cord Signup and view all the answers

What significant development occurs in the fetus by the 3rd month regarding external genitalia?

The testicles are visible inside the scrotum via ultrasound. Signup and view all the answers

Which physical changes are observed in the fetus during the 3rd month of development?

Facial features become more human-like and the limbs attain relative length. Signup and view all the answers

What is the percentage chance of survival for a fetus at the 7th month of gestation?

90% Signup and view all the answers

What characteristic distinguishes the skin of a fetus at 6 months of gestation?

Reddish and wrinkled due to lack of connective tissue Signup and view all the answers

At which developmental stage can fetal movement be typically felt by the mother?

4th to 5th month Signup and view all the answers

What term describes the fine hair covering the fetus around the 4th to 5th month?

Lanugo Signup and view all the answers

What notable feature is observed on a baby born at the 8th month of gestation?

Vernix caseosa covering the body Signup and view all the answers

How can the month of pregnancy be determined if the last menstrual period is unknown?

By observing fetal movement. Signup and view all the answers

At what point in development is the skull circumference of the fetus larger than other body parts?

9 months Signup and view all the answers

What is the typical weight range of a full-term baby at birth?

3,000 to 3,400 g Signup and view all the answers

What happens to the intestines around the 6th week of fetal development?

They cause herniation within the umbilical cord. Signup and view all the answers

What is a characteristic feature of the fetal skin during the 3rd month?

It is thin enough to see the underlying blood vessels. Signup and view all the answers

When is subcutaneous fat deposition notably visible in the growth of a fetus?

At 18 weeks Signup and view all the answers

Which of the following is NOT a feature of the fetus during the 4th and 5th month?

Breathing movements begin. Signup and view all the answers

What is the correct duration of pregnancy calculated from the last normal menstrual period to determine full-term?

40 weeks Signup and view all the answers

What is the fundamental role of the umbilical cord in fetal development?

It transports oxygen and nutrients from the placenta Signup and view all the answers

Study Notes

Development of Fetus

Fetal development begins at the 9th week and continues until birth, with significant maturation of tissues and organs.
Crown-rump length (CRL) measures from the top of the head to the heel, reaching approximately 36 cm at full term.
Crown-heel length (CHL), measuring from the head to the heel in a standing position, can reach up to 51 cm.
During the 3rd month, primary ossification centers form, and external genitalia develop, allowing sex determination via ultrasound.
By the end of the 3rd month, the fetus resembles a human, with notable facial features and thin skin showing blood vessels beneath.

Monthly Changes

3rd Month: Rapid growth; limbs reach proportionate lengths; external genitalia become distinguishable.
4th and 5th Months: Development of lanugo hair; fetal movements felt by the mother; significant length increase.
6th Month: The respiratory and central nervous systems are not fully developed; survival chances are low.
7th Month: Developmental milestones achieved; 90% chance of survival; sucking and swallowing mechanisms functional.
8th Month: Presence of vernix caseosa, a whitish protective substance on the skin, indicating gestational age.
9th Month: Skull is the largest part of the body; head circumference important for delivery, especially in breech presentations.

Time of Birth

A full-term pregnancy is typically around 280 days or 40 weeks from the last normal menstrual period (LNMP).
Accurate age calculation starts from fertilization, approximating 266 days or 38 weeks.

Placenta

Fully developed placenta serves vital functions including nutrient transfer and waste disposal.
Composed of fetal and maternal components; fetal side derived from trophoblast and extraembryonic mesoderm, maternal side from uterine endometrium.
The placental barrier selectively permits substances to pass, protecting the fetus.

Umbilical Cord

Connects the fetus to the placenta, facilitating nutrient and oxygen exchange via blood vessels.
Critical for fetal development, providing necessary support throughout pregnancy.

Amniotic Fluid

Surrounds the fetus, providing cushioning, temperature regulation, and facilitating movement, which is important for muscle and bone development.

Parturition (Birth)

Involves three stages of labor: dilation, expulsion, and placental delivery.
Proper fetal positioning during birth is crucial, with head circumference being a key measurement for safe delivery.

Weight and Size at Birth

Average fetal weight at term ranges from 2,500 to 4,000 grams, with a typical length of about 51 cm.
Normal fetal size assessment is essential for pregnancy management, especially in cases of potential complications. Low Birth Weight (LBW) is defined as weight below 2,500 grams.

Ultrasound and Fetal Monitoring

Ultrasound is vital for determining gestational age and fetal development, measuring CRL, biparietal diameter, abdominal circumference, and femur length.

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Description

Explore the fascinating journey of fetal development from the 9th week until birth. This quiz covers key milestones such as organ maturation, size measurements, and notable changes during each month of pregnancy. Test your knowledge on the critical stages and factors influencing fetal growth.