Teratogens

Development and the Prenatal Environment

Teratogen – from teras for “monster” and genesis for “origin,” any agent that can cause permanent damage to the embryo or fetus

Dose-response effect: the relationship between the dosage of a substance and the result of exposure

Threshold effect: related to the dose-response effect, the point of exposure below which no effect can be identified

Sensitive Periods in Prenatal Development

Alcohol

Alcohol is one of the most common causes of birth abnormalities and one of the most preventable causes of birth defects. Fetal Alcohol Syndrome (FAS): characterized by

distinctive facial features, intellectual disabilities (IQ less than 70), and physical growth below the 10th percentile in height or weight for age and race.

Fetal Alcohol Syndrome

• FAS can cause many physical, mental and behavioral abnormalities

• Caused by maternal moderate to heavy drinking during the embryonic period

• Most harm is often done before the mother even knows she is pregnant.

Tobacco

Women who smoke during pregnancy are twice as likely to experience two specific complications: Placenta previa: a condition in which the placenta attaches

low on the wall of the uterus, with the potential to cause bleeding late in pregnancy

Placenta abruptio: a life-threatening emergency condition in which the placenta peels away from the wall of the uterus, causing massive bleeding

Drugs and Medications

Cocaine: This powerful stimulant directly affects the brain, heart rate, and blood pressure of both mother and fetus. Increases the risk of miscarriage, premature birth, and death.

Opiates: Women taking opiates are six times more likely to experience complications during pregnancy. The fetus may experience withdrawal symptoms, which causes fetal distress.

OTC Medications

Medications: The FDA has a classification system for drugs to guide physicians’ decisions regarding medications.

Herbal medicines and supplements: Chemical compounds created by nature are largely unregulated. Women should discuss the use of these substances with their professional health care provider.

Maternal Disease, Illness, and Stress

Communicable diseases: may be caused by viruses, bacteria, or parasites that cross the placenta or are transmitted during vaginal birth. Some diseases may cause serious birth defects depending on timing and extent of exposure.

HIV and AIDS: attacks the immune system, leaving the person vulnerable to infections and eventually leading to death. AIDS can be transmitted during pregnancy, vaginal birth, and breastfeeding.

Diabetes Mellitus: Diabetes affects more women than HIV/AIDS and all sexually transmitted diseases combined. A chronic condition characterized by high glucose (sugar) in the blood. Early in pregnancy, it may cause heart defects and hydrocephalous (excess fluid in the brain). Later, it can lead to the development of insulin resistant diabetes in the fetus.

Maternal Stress: High levels of maternal stress and anxiety may increase the risk for miscarriage and premature labor.

Environmental Pollutants and Hazards

Radiation: Prior to 8 weeks of fetal development, abnormalities of major organs and limb deformities are apparent. Between 8 and 15 weeks, there is an increased risk of microcephaly (small brain) and severe intellectual disabilities.

Environment Chemicals: Chemicals may cause neurological disorders, severe developmental delays, cerebral palsy, diseases of the eyes and lungs, chromosomal abnormalities, impaired motor function, cognitive problems, and four times the normal rate of miscarriage.

Health During Pregnancy

Physiology of pregnancy: The uterus grows to 20 times its normal size, there is a 15 – 20% increase in oxygen intake, the woman’s heart enlarges 12% and pumps 30 to 50% more blood. Morning sickness, fatigue, and swelling in the legs and ankles are common. Some may experience shortness of breath when lying down due to pressure on the diaphragm.

Recommendations for a Healthy Pregnancy

Recommendations for a Healthy Pregnancy

Gestational Diabetes

High-Risk Pregnancies

Prenatal care: health care during pregnancy which monitors health of mother and baby, provides education and counseling about pregnancy, birth, and newborns to women and their partners Preeclampsia: a treatable medical condition that begins

after the 20th week, characterized by high blood pressure, protein in the urine, and sometimes swelling

Eclampsia: a medical emergency which left untreated leads to maternal seizures and/or coma and even death of mother and baby

Ectopic pregnancy: a condition in which the blastocyst phase of the embryo implants outside of the uterus, usually in the fallopian tube, where it cannot continue to develop. It quickly outgrows the space, resulting in pain and possible rupture of the fallopian tube.

Rh incompatibility: a complication of pregnancy in which a mother who is Rh negative carries an Rh-positive fetus; under certain conditions, antibodies in the mother’s blood can attach the fetus’s red blood cells.

Access to health care: Nearly 1 million pregnant women in the United

States do not receive adequate prenatal care. Lack of access to quality affordable health care

increases the risk of complications.