Download The Fetal Period (9th-38th Week)

The Fetal Period (9th-38th Week)
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Chronology of Human Development
Day 1 - conception takes place.
7 days - blastocyst implants in mother’s uterus.
18 days - heart begins to beat.
4 weeks - eye, ear and respiratory system begin to form.
6 weeks - brain waves recorded, skeleton complete, reflexes present.
8 weeks - all body systems present.
12 weeks - weighs one ounce.
16 weeks - genital organs clearly differentiated, fetus kicks and turns
20 weeks - has hair on head, weighs one pound, 12 inches long.
23 weeks - 15% chance of viability outside of womb if birth premature.
24 weeks - 56% of babies survive premature birth.
25 weeks - 79% of babies survive premature birth.
10 week fetus
Video of Embryonic
Development
http://www.pbs.org/wgbh/nova/miracle/program.html
10 Week Old Fetus and Placenta
Development of the Placenta and Fetal Membranes
Implantation of the Blastocyst (Day 7)
By 8 Days, the Amniotic Cavity Appears
By 9 Days, the Embryo is Completely Implanted
in the Uterine Endometrium
Days 10-13 of Embryonic Development
Days 12-15 of Embryonic Development
Formation of the Chorionic Villi
Human Embryo at the Beginning of the
Second Month of Development
Transverse Section through a Full Term
Placenta
Functions of the Placenta
1.) provide nutrients and oxygen
2.) remove metabolic waste
3.) provide maternal antibodies
4.) produce steroid hormones
(estrogen and progesterone)
to maintain pregnant state
5.) produce HCG to support
corpus luteum
http://www.pbs.org/wgbh/nova/miracle/program.html
6.) produce prostaglandins which
is involved in maintenance of
pregnancy and onset of labor.
RH Incompatibility: Erythroblastosis Fetalis
Rh factors are a group of surface molecules that are present on the
surface membrane of red blood cells in most individuals.
Rh factors provoke a strong immune response in Rh- individuals
Anti-Rh antibodies can be administered to the Rh- mother immediately
after birth of each Rh+ baby. These antibodies destroy Rh+ red blood
cells in her circulation before they stimulate her own immune response;
this prevents her from manufacturing anti-Rh antibodies.
Prenatal Screening Techniques
Amniocentesis
-usually between 15-18 weeks of gestation
-.5% fetal loss with Amniocentesis
Chorionic Villus Sampling
- performed 10-12 weeks of gestation
- 0.8-1.0% fetal loss with CVS
Ultrasonography
Transducer produces a stream of inaudible, high frequency sound
waves (3.5-7.0 megahertz) that penetrate the body and bounce off
organs inside.
Example of Ultrasound
Ultrasound can be used to determine gestational age
and assess fetal size
a) The Crown-rump length (CRL)
This measurement can be made between 7 to 13 weeks and gives
very accurate estimation of the gestational age.
b) The Biparietal diameter (BPD)
The diameter between the 2 sides of the head. This is measured
after 13 weeks. It increases from about 2.4 cm at 13 weeks to about
9.5 cm at term. Different babies of the same weight can have
different head size, therefore dating in the later part of pregnancy is
generally considered unreliable.
c) The Femur length (FL)
Measures the longest bone in the body and reflects the longitudinal
growth of the fetus.
d) The Abdominal circumference (AC)
The single most important measurement to make in late pregnancy.
It reflects more of fetal size and weight rather than age.
2-D Versus 3-D Ultrasonography
Body Changes during Pregnancy
Your Changing Body
1 Month
3 Months
6 Months
9 Months
Weight Gain During Pregnancy
Total Weight Gain = 24-30lbs
External and Internal Fetal Monitoring
Approaches
Fetal Monitoring Graph
Fetal
Heartbeat
Uterine
Contractions
Presentation Positions
97% of all Preg.
2.5% of all Preg.
<.5% of all Preg.
Cesarean Section
Occurs about 20-25% of the time
4 Stages of Labor
Stage 1: begins with the onset of true labor contractions
and lasts until the cervix is completely dilated.
Stage 2: begins when the cervix is completely dilated
and ends when the baby is born.
Stage 3: begins after the baby is delivered and ends when
the placenta is expelled.
Stage 4: begins when the placenta is expelled and lasts until
the woman’s medical condition is stabilized.
First Stage of Labor
Common Methods of Anesthesia
Negotiating the Birth Canal
Common Types of Episiotomies
Stage 2: Delivery of Baby and Placenta
Serge and Melinda are having a
baby
http://www.pbs.org/wgbh/nova/miracle/program.html