Stress represents the effects of any factor able to threaten the homeostasis of an organism; these either real or perceived threats are referred to as the “stressors” and comprise a long list of potentially adverse factors, which can be emotional or physical. Because of a link in blood supply between a mother and fetus, it has been found that stress can leave lasting effects on a developing fetus, even before a child is born. The best-studied outcomes of fetal exposure to maternal prenatal stress are preterm birth and low birth weight. Maternal prenatal stress is also considered responsible for a variety of changes in the child’s brain, and a risk factor for conditions such as behavioral
3. STDs during Pregnancy - CDC Fact Sheet. Centers for Disease Control and Prevention. Retrieved from https://www.cdc.gov/std/pregnancy/stdfact-pregnancy.htm
4. Maternal Illness – Birth Defect Prevention for Expecting Parents. Birth Defect Research for Children. Retrieved from https://www.birthdefects.org/healthy-baby/maternal-illness/
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problems, learning disorders, high levels of anxiety, attention deficit hyperactivity disorder, autism, and schizophrenia. Furthermore, maternal prenatal stress has been associated with a higher risk for a variety of immune and metabolic changes in the child such as asthma, allergic disorders,
cardiovascular diseases, hypertension, hyperlipidemia, diabetes, and obesity.5
Factors influencing prenatal risks
There are several considerations in determining the type and amount of damage that might result from exposure to a particular teratogen (Berger, 2004). These include:
• The timing of the exposure: Structures in the body are vulnerable to the most severe damage when they are forming. If a substance is introduced during a particular structure’s critical period (time of development), the damage to that structure may be greater. For example, the ears and arms reach their critical periods at about 6 weeks after conception. If a mother exposes the embryo to certain substances during this period, the arms and ears may be malformed.
• The amount of exposure: Some substances are not harmful unless the amounts reach a certain level. The critical level depends in part on the size and metabolism of the mother.
• Genetics: Genetic make-up also plays a role in the impact a particular teratogen might have on the child. This is suggested by fraternal twin studies who are exposed to the same prenatal environment, yet do not experience the same teratogenic effects. The genetic make-up of the mother can also have an effect; some mothers may be more resistant to teratogenic effects than others.
• Being male or female: Males are more likely to experience damage due to teratogens than are females. It is believed that the Y chromosome, which contains fewer genes than the X, may have an impact.
5. Douros Konstantinos, Moustaki Maria, Tsabouri Sophia, Papadopoulou Anna, Papadopoulos Marios, Priftis Kostas N. (2017).
Prenatal Maternal Stress and the Risk of Asthma in Children. Frontiers in Pediatrics. Retrieved from https://www.frontiersin.org/article/10.3389/fped.2017.00202
Figure 7. Critical Periods of Prenatal Development. This image summarizes the three developmental periods in prenatal development. The blue images indicate where major development is happening and the aqua indicate where refinement is happening. As shown, the majority of organs are particularly susceptible during the embryonic period. The central nervous system still continues to develop in major ways through the fetal period as well.
Interactive Example
Did you know that pregnant women can improve outcomes for themselves and their babies through a balanced diet and adequate exercise? Click through this interactive to learn more about the importance of maternal health.
An interactive or media element has been excluded from this version of the text. You can view it online here:
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Figure 8. Pregnancy affects women in different ways; some notice few adverse side effects, while others feel high levels of discomfort, or develop more serious complications.
Complications of Pregnancy and Delivery
There are a number of common side effects of pregnancy.
Not everyone experiences all of these nor do women experience them to the same degree. And although they are considered “minor” these problems are potentially very uncomfortable. These side effects include nausea
(particularly during the first 3-4 months of pregnancy as a result of higher levels of estrogen in the system), heartburn, gas, hemorrhoids, backache, leg cramps,
insomnia, constipation, shortness of breath or varicose veins (as a result of carrying a heavy load on the abdomen).
What is the cure? Delivery!
Major Complications
The following are some serious complications of
pregnancy which can pose health risks to mother and child and that often require special care.
• Gestational diabetes is when a woman
without diabetes develops high blood sugar levels during pregnancy.
• Hyperemesis gravidarum is the presence of severe and persistent vomiting, causing dehydration and weight loss. It is more severe than the more common morning sickness.
• Preeclampsia is gestational hypertension. Severe preeclampsia involves blood pressure over 160/110 with additional signs. Eclampsia is seizures in a pre-eclamptic patient.
• Deep vein thrombosis is the formation of a blood clot in a deep vein, most commonly in the legs.
• A pregnant woman is more susceptible to infections. This increased risk is caused by an increased immune tolerance in pregnancy to prevent an immune reaction against the fetus.
• Peripartum cardiomyopathy is a decrease in heart function which occurs in the last month of pregnancy, or up to six months post-pregnancy.