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UNSW Embryology

Abnormal Development - Maternal

© Dr Mark Hill (2011)

Acknowledgements

Introduction

Materal effects should really be called environmental (in contrast to genetic) removing the association of mother with the deleterious agent. Accepting this caveat, there are several maternal effects from lifestyle, environment and nutrition that can be prevented or decreased by change which is not an option for genetic effects.

congenital syphilis
Young child with smallpox scars (Image CDC)

Infections, collectively grouped under the acronym TORCH for Toxoplasmosis, Other organisms (parvovirus, HIV, Epstein-Barr, herpes 6 and 8, varicella, syphilis, enterovirus) , Rubella, Cytomegalovirus and Hepatitis. See related pages on Maternal Hyperthermia and Bacterial infections.

Maternal diet the best characterised is the role of low folic acid and Neural Tube Defects (NTDs) see also Abnormal neural development and Neural Tube Defects and the sample environmental effects listed below.

Maternal drugs effects either prescription drugs (therapeutic chemicals/agents, thalidomide limb development), non-prescription drugs (smoking), and illegal drugs (Cannabis/Marijuana, Methamphetamine/Amphetamine, Cocaine, Heroin, Lysergic Acid Diethylamide)

Environment (smoking, chemical, heavy metals) and maternal endocrine function (maternal diabetes, thyroid development) and maternal stress.

Different environmental effects can act individually or in combination on the same developing system. For example, neural development can be impacted upon by alcohol (fetal alcohol syndrome), viral infection (rubella) and/or inadequate dietry folate intake (neural tube defects). These effects may also not be seen as a direct effect on a system or systems but result in a reduced birth weight and the potential postnatal developmental effects.

Finally, when studying this topic remember the concept of "critical periods" of development that will affect the overall impact of the above listed factors. This can be extended to the potential differences between prenatal and postnatal effects, for example with infections and outcomes.

Low Birth Weight

The USA for "Disorders relating to short gestation and unspecified low birthweight" in 1980 was the 4th highest cause of infant mortality (3,648), in 2002 it was ranked 2nd (4,637) (Data: table 32, Health, United States, 2004). In addition to mortality, there is strong evidence that interuterine environment has an influence on later postnatal health and neurological development. This theory is based on the early statistical analysis of disease/longevity in babies with low birth weights in England by Barker, and was initially called the "Barker Hypothesis" and now called the Fetal Origins Hypothesis.

Birth Weight Definitions:

Low Birth Weight (less than 2,500 g or 5 lb, 8 oz)

Very Low Birth Weight (less than 1,500 g or 3 lb, 5 oz)

Extremely Low Birth Weight (less than 1,000 g or 2 lb, 3 oz).

Links: Fetal Origins Hypothesis | Health Services/Technology Assessment Text (HSTAT, USA) 70. Criteria for Determining Disability in Infants and Children: Low Birth Weight | Health, United States, 2004 table 32. Leading causes of death and numbers of deaths, according to age: United States, 1980 and 2002

References:

Sheridan C.    [See Related Articles] Intrauterine growth restriction--diagnosis and management. Aust Fam Physician. 2005 Sep;34(9):717-23.

Maternal Stress

There is mainly anechdotal evidence in humans linking maternal stress to pregnancy loss. A recent paper (Nepomnaschy etal., 2006) has attempted to initially address this scientifically by measuring a marker of stress (urinary cortisol levels) to correlate with the occurance of spontaneous abortion. Note that altered urinary cortisol levels can also be associated with other endocrine disorders and medications. "...We examined the association between miscarriage and levels of maternal urinary cortisol during the first 3 weeks after conception. Pregnancies characterized by increased maternal cortisol during this period (within participant analyses) were more likely to result in spontaneous abortion (P < 0.05)." Nepomnaschy PA, Welch KB, McConnell DS, Low BS, Strassmann BI, England BG. Cortisol levels and very early pregnancy loss in humans. Proc Natl Acad Sci U S A. 7 March 2006; Vol. 103, No. 10

Links: Endocrine Abnormalities | MedlinePlus Cortisol - urine

References:

Nepomnaschy PA, Welch KB, McConnell DS, Low BS, Strassmann BI, England BG.    [See Related Articles] Cortisol levels and very early pregnancy loss in humans. Proc Natl Acad Sci U S A. 7 March 2006; Vol. 103, No. 10

Mastorakos G, Ilias I.    [See Related Articles] Maternal and fetal hypothalamic-pituitary-adrenal axes during pregnancy and postpartum. Ann N Y Acad Sci. 2003 Nov;997:136-49.

TORCH Infections

Maternal viral, protozoan and bacterial infections (the most commonly occuring are rubella, cytomegalovirus and toxoplasmosis) and can have a variety of different effects on development from insignificant to fetal morbidity and abortion.

Often most serious effects are often seen in the long developing neural system and the associated sensory system (hearing, vision).

There are several prenatal diagnostic techniques that can be used to identify specific infections, but in some cases infections go maternally undiagnosed and only seen by the developmental impact of the infection.

Toxoplasmosis | Other organisms (parvovirus, HIV, Epstein-Barr, herpes 6 and 8, varicella, syphilis, enterovirus) | Rubella, Cytomegalovirus | Hepatitis. (See also a page on bacterial infections)

References:

Khan NA, Kazzi SN.    [See Related Articles] Yield and costs of screening growth-retarded infants for torch infections. Am J Perinatol. 2000;17(3):131-5.

Abdel-Fattah SA, Bhat A, Illanes S, Bartha JL, Carrington D.    [See Related Articles] TORCH test for fetal medicine indications: only CMV is necessary in the United Kingdom. Prenat Diagn. 2005 Nov;25(11):1028-31.

Bailao LA, Osborne NG, Rizzi MC, Bonilla-Musoles F, Duarte G, Bailao TC.    [See Related Articles] Ultrasound markers of fetal infection part 1: viral infections. Ultrasound Q. 2005 Dec;21(4):295-308.

Newton ER.    [See Related Articles] Diagnosis of perinatal TORCH infections. Clin Obstet Gynecol. 1999 Mar;42(1):59-70; quiz 174-5.

Maternal Factors Prenatal

Alcohol "Fetal Alcohol Syndrome" | Smoking | Chemical | Drug Use | Legal Drugs | Trauma | Nutrition | Iodine Deficiency

Infection: viral infection | Rubella | bacterial infection | cytomegalovirus

Merck Manual (external links require online access): Women's Health Issues | Risk Factors Present Before Pregnancy | Risk Factors That Develop During Pregnancy | Diseases that complicate Pregnancy | Problems Affecting the Fetus or Newborn | Heart Disease | Heart Failure | Rheumatic Heart Disease | Birth Defects of Heart | Mitral Valve Prolapse | High Blood Pressure | Anemias | Kidney Disease | Infectious Disease | Diabetes | Thyroid | Liver | Asthma | Systemic Lupus Erythematosus | Rheumatoid Arthritis | Myasthenia Gravis | Idiopathic Thrombocytopenic Purpura | Surgery During Pregnancy

Glossary of Terms

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers

WWW Links

Organization of Teratology Information Specialists (USA) OTIS | OTIS Fact sheets

Quick Links

Finally

For those wanting to see dynamic processes of development (and have a reasonably quick connection) then the Movies pages are good for watching changes occur.

Other Embryos

The study of human development has relied extensively on studying the process in other model animals. For those wanting to see the process of development in other species then the other embryos pages are a good start.

UNSW Embryology ISBN: 978 0 7334 2609 4

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