Teratogens, Infertility, and Sex

Chromosome disorders

Ms. Chabot

Honors Anatomy & Physiology

Definitions• Teratogen

– Agent or factor that causes malformation of an

embryo

– Can cause a birth defect

– Can lead to loss of the pregnancy

– Usually due to maternal exposure during

pregnancy

• Teratology

– Study of abnormalities of development

Periods of Fetal Development• To understand the

impact of

teratogens, you

need to know a

little about fetal

development.

• The dates shown

at right are

predictable events

during the 40 week

period of human

gestation.

• Human viability is

now possible as

early as 24 weeks.

Fetal Alcohol Syndrome

What is FAS?• Alcohol is the teratogen that leads to poor

development of the fetus.

– Damage can occur in the first few weeks of

pregnancy

– Risk increases with level of alcohol consumption

• In addition to physical features, children

experience:

– Poor vision and hearing

– Attention span and memory issues

– Learning and speech communication problems

Medications• Many prescription drugs are known teratogens

• Prescription guidelines require special labeling

• Impact on fetus will vary, dependent on drug

category

• Examples:

– ACE inhibitors for blood pressure

– Acne medicine like Acutane

– Antibiotics like tetracycline

– Seizure medications like Dilantin and Depakote

– Thalidomide for nausea

Thalidomide

Thalidomide• Prescribed in the 1950’s to treat nausea n

pregnant women in Europe and Canada.

• Children born to women that took thalidomide

suffered from PHOCOMELIA.

– Severe malformation of the limbs

– Absent pelvis

– Can also result in undeveloped nose, disfigured

ears, small jaw, and cleft lip/palate

• 10,000 cases reported

• These cases led to more rigorous testing and

prescription regulations for pregnant women.

Accutane

Accutane• Used to treat severe acne.

• Prescription requires women of childbearing

age to also take birth control to prevent

counseling and/or participate in counseling.

• 70-80% efficacy in treating cystic acne.

• Neonatal deformities include:

– Cleft palate

– Heart defects

– Hydrocephalus

– CNS malformations

Environmental Exposure

Environmental Exposure

• Can include

– Pesticides

– Pollution

– Radiation exposure

– Infection during pregnancy

• Often results in malformation of the CNS due

to early exposure

• Pesticide exposure most common in

agricultural areas

Infertility

Infertility Definitions

• Inability to

– Conceive after 12 consecutive months of regular

intercourse without use of “unmentionables”

– Produce gametes

– Carry a pregnancy to term

• 20% are due to issues with the man

• 50% are due to issues with the woman

• 30% are unidentified/unexplained

Infertility Risk Factors

• Age

• Smoking

• Alcohol

consumption

• Obesity

• Eating disorders

• STD’s

• Stress

Increasing Infertility?

• 1 in 6 couples have difficulty conceiving.

• Sperm counts have fallen by almost half in the

last 60 years.

– Millions of healthy, motile sperm are needed for 1

to fertilize an egg

– Not only are counts going down, sperm are more

abnormal in shape and motility

• Increased rates of chlamydia resulting in PID

• More women waiting until later in life to start a

family.

Treating Infertility

• Induce ovulation

• Surgery to unblock Fallopian

tubes

• IVF

• ICSI

Septuplet Ultrasound

Quadruplet Ultrasound