Prenatal Development: Environmental Factors (II)

B. Teratogens and Health Problems of the Mother

• Teratogens are environmental agents that can harm the embryo or fetus (e.g., drugs, alcohol, radiation, etc.)
• The harmful effects of teratogens varies according to the critical period that correspond to the times when organs are developing.
• For example, the heart is most vulnerable to certain teratogens in the third to fifth weeks after conception. Thus, the same teratogens that can harm a 4-week-old embryo may have no effect on a 4-month-old fetus.

Sexually Transmitted Infections

1) Syphilis

• Syphilis bacterium can cause miscarriage, stillbirth or congenital syphilis.
• If an infected mother is treated with an antibiotic before the fetus is 4-month old, the fetus may not get affected.
• If the mother isn't treated, there will be a 40-70% chance for the fetus to have congenital syphilis.
• Symptoms of congenital syphilis include:
• skin sores
• bloody and runny nose
• slimy patches in mouth
• inflamed bones in the arms and legs
• jaundice
• anemia
• small head
• Congenital syphilis can:
• impair vision and hearing
• damage the liver
• deform the bones and teeth
• Untreated babies may develop mental retardation or have seizures.

2) HIV/AIDS

• HIV or AIDS disables the body's immune system and expose victims to fatal illnesses such as respiratory problems and cancer.
• HIV can be transmitted to a baby while childbirth and breast-feeding.

Rubella

• If during the 20 weeks of pregnancy a women gets infected by this viral infection, there is 20% chance that the baby will have defects such as:
• deafness
• mental retardation
• heart disease
• eye problem, including blindness
• Women who are not immune to this viral are best vaccinated before pregnancy.

Toxemia

• Toxemia is a severe condition characterized by high blood pressure that may occur in the latter week of pregnancy, worst can cause maternal deaths.
• Rather than transmitted to the embryo and fetus, toxemia affect the environment in which it develops.
• Women with toxemia often have premature and undersized babies.
• Toxemia is linked with malnutrition, and women who did not receive prenatal care are more likely to die from toxemia.

Rh Incompatibility

• Rh factor is a protein on red blood cells.
• In Rh Incompatibility, pregnant women produce and transfer antibodies to a fetus or inborn.
• These antibodies can cause:
• brain damage
• anemia
• death
• It occurs when a pregnant woman has a Rh-positive blood while her unborn baby has a  Rh-negative blood.
• The mother produces Rh-positive antibodies to the baby's Rh-positive blood when there's an exchange of blood between the mother and her baby occurs during childbirth.
• These antibodies usually don't affect the first child because the baby is born before the antibodies develop.
• But, children from subsequent pregnancies are likely to get affected by these antibodies.
• These antibodies will not developed if the mother is injected with Rh immunoglobulin within 72 hours after delivery.
• Also, a fetus or infant who is at risk of Rh disease may receive blood transfusion to remove the mother's antibodies .

Reference:
Rathus, S. A. (2008). Childhood and Adolescence: Voyages in Development. Belmont, CA: Thomson Wadsworth.

Other teratogens are explained here.