3.4 Gestation and Birth

Question 1

How long does human gestation last?

Answer 1

280 days.

Question 2

What develops in the first trimester?
Heart beats.
Length at 5 and 6 weeks.
Bones form.
Considered fetus.

Answer 2

First Trimester: Major organs begin to develop.
Heart beats: 22 days.
5 Weeks: 10 mm in length
6 Weeks: 15 mm in length.
Bones Harden: 7th week
Considered Fetus: after 8 weeks, most organs have formed.

Question 3

What happens in the second semester?

Answer 3

Mostly growing.
The face has a human appearance.
Toes and fingers get longer.
At the end of 6th months, it is 30-36 cm long (36 cm= 14 inches)

Question 4

What happens in the third semester?

Answer 4

More rapid growth.
Antibodies are transported to the fetus for protection. It is most active in the ninth month just before birth.

Question 5

If a baby is born at 24 weeks, what are the organs most affected?

Answer 5

Respiratory, GI, and nervous system.

Question 6

What is parturition?

Answer 6

Vaginal childbirth.

Question 7

What hormones mediate childbirth? (X2)

Answer 7

Oxytocin and prostaglandins.

Question 8

What are the three phases of child birth?

Answer 8

1. Cervix thins out and the amniotic sac ruptures.
2. Strong uterine contractions result in the birth of the fetus.
3. The placenta and umbilical cord are expelled.