Third Month to Birth: The Fetus

Question 1

When does the greatest length increase occur?

Answer 1

months 3, 4, and 5

Question 2

When does the greatest weight increase occur?

Answer 2

months 8 and 9

Question 3

Length of pregnancy

Answer 3

38 weeks (266 days) after fertilization or 40 weeks after the last menstrual period

Question 4

When does the external genitalia develop?

Answer 4

week 12 (the sex of the fetus can be determined by ultrasound)

Question 5

Highlights of 13 to 16 weeks

Answer 5

growth is very rapid here, limb movements are more coordinated, face becomes more human-looking, by 16 weeks the ovaries are differentiated and contain primordial follicles that have oogonia

Question 6

Highlights of 17 to 20 weeks

Answer 6

growth slows down, movements are felt by mother, brown fat forms, testes begin to descend

Question 7

Highlights of 21 to 25 weeks

Answer 7

substantial weight gain, secretory epithelial cells in the lung have begun to secrete surfactant, sucking movements and can react to sounds, respiratory system immature

Question 8

Highlights of 26 to 29 weeks

Answer 8

lungs have developed sufficiently for gas exchange, CNS has matured where it can direct rhythmic breathing and control body temp., formation of red blood cells moves to bone marrow

Question 9

Highlights of 30 to 34 weeks

Answer 9

pupillary light reflex of the eyes, 32 weeks and older typically survive if born

Question 10

Highlights of 34 to 38 weeks

Answer 10

finishing period, circumference of head and the abdomen are approx. equal, growth slows, CRL of 36cm, CHL of 50cm, and weigh approx. 3000-3400g