Problems in Prenatal Development

Chapter 8

Miscarriage

Miscarriage—spontaneous loss of the pregnancy after less than 20 weeks of fetal development• the zygote, embryo, or fetus dies

and is expelled from the mother’s body

• between 15-20% of known pregnancies end in miscarriage

• many other pregnancies end before the mother even knew she was pregnant

Miscarriage Myths

• physical activity, stress, and minor falls are NOT believed to cause the loss of pregnancy

• Miscarriages that occur early in pregnancy are usually due to a genetic abnormality– Most often the problem was not inherited, but

happened by chance– Couples could not have done anything to prevent

the miscarriage– Most of these couples are able to have a successful

pregnancy later

Risk Factors for Miscarriage

• age: women over age 35 are at a greater risk• having had a previous miscarriage• family history of miscarriage• certain diseases or infections• exposure to hazards during pregnancy such

as: alcohol, drugs, smoking, heavy caffeine use, or certain chemicals

Stillbirth

• Stillbirth if the fetus dies after the 20th week of pregnancy

• occurs in 1 out of 200 pregnancies

• death can occur during labor or delivery, but more often it occurs before labor

• causes vary and sometimes no cause can be found

Ectopic Pregnancy

• Ectopic Pregnancy—when a fertilized egg implants outside the uterus

• in most cases, the egg implants in the fallopian tube• another name for ectopic pregnancy is: Tubal

Pregnancy• without the nourishment and protection of the

uterus, the embryo cannot survive• Risk to mother’s health: as embryo grows, it may

eventually burst the fallopian tube– This can cause life threatening bleeding

• -physician must end a discovered ectopic pregnancy

Premature Labor and Birth

• Premature Labor and Birth—when labor and/or birth occurs before the 37th week of pregnancy

• about 1 out of every 10 babies is premature• Premature babies have less time to develop in the

uterus • babies with the most serious health problems:

babies born before 26 weeks and weigh less than 2 pounds– These babies underdeveloped lungs, fluid accumulation

in the brain, seizures, and growth and learning delays

Prenatal Testing• Various tests are used to determine if the fetus has a birth defect or

other health problem• Some tests reveal other info such as if the new arrival will be a boy

or a girl• Some tests, such as various blood tests are routinely given to

almost all pregnant women• Other tests are warranted only when there is reason to suspect a

problem• A family history of genetic defect is another possible reason for

prenatal testing• EVEN WHEN A DR. RECOMMENDS PRENATAL TESTING, THE

MOTHER-TO-BE CHOOSES WHETHER OR NOT TO UNDERGO THE PROCEDURE

• Most prenatal tests involve some risks

Ultrasound Imaging• Ultrasound imaging—uses sound waves to create video

and still images of the fetus inside the uterus– A woman lies on a padded table– A technician applies thick, clear gel to woman’s abdomen

and rubs a transducer (handheld device) over the area covered by the gel

– Sound waves bounce off the fetus’s bones, tissues, and organs producing images that are viewed on a monitor

• ultrasound image—often called a sonogram– involves little or NO risk– Used to check fetal position and movement, measure fetus’s

heart rate, and asses whether prenatal development is proceeding normally

– can reveal the fetus’s gender and the presence of twins

Amniocentesis• Amniocentesis—test involving removing a small amount

of amniotic fluid that surrounds the developing fetus• while viewing an ultrasound, a doctor guides a needle

thru the abdomen and wall of the uterus• performed at 15 to 18 weeks of pregnancy, but is

sometimes done as early as 11 weeks• slightly increases the risk of miscarriage so it is NOT

routinely offered• reasons for amniocentesis:

– check for genetic or chromosomal problems– if woman is over age 35– if there is a family history of genetic disorders– if blood tests indicate a problem

Amniocentesis

Chorionic Villi Sampling

• Chorionic Villi Sampling (CVS)—take a sample of cells from the placenta

• What are Chorionic Villi?– They are microscopic, fingerlike projections on the placenta

• insert a tube/needle thru abdomen or vagina– Ultrasound is used to guide the tube or needle– The cells are removed and checked for their genetic structure

• Doctors can use this to test for about 200 genetic defects

• Chorionic Villi Sampling is preformed at 10 to 12 weeks of pregnancy

• higher risks only done if a serious problem is suspected

Chorionic Villi Sampling