Later Development

• at ~ 8 weeks > fetus

• human gestation 38 weeks (from conception)

Do not copy these notes on later development.....

1 to 2 inches long

heart has divided into right and left chambers.

3 inches long

organs and muscles beginning to function

baby is covered with a layer of thick, downy hair called lanugo (La nu go).

heartbeat can be heard clearly.

baby's first kicking.

lungs are filled with amniotic fluid

breathing motions begin.

can hear sounds.

turned head down in preparation for birth

4 - 5 pounds

6 - 8 pounds

18-22 inches

Stages of Childbirth

1. Dilating Stage

• the uterus contracts mildly at first then strongly and regularly (early and active labour).

• cervix dilates with each contraction, and the baby’s head rotates to fit through the mothers pelvis.

• leads to a transition phase of intense contractions and full dilation of the cervix

2. Expulsion stage• the mother pushes, or bears down, in

response to pressure against her pelvic muscles.

• baby’s head becomes visible

• babys shoulders, which emerge one at a time with the next contractions. The rest of the body then slides out relatively easily

• the umbilical cord is sealed and cut.

3. Placental stage

• within ten minutes of the baby’s birth.

• uterus continues to contract, expelling the severed umbilical cord and placenta.