Prenatal factors affecting growth and development of fetus pdf
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- Prenatal Risk Factors for Developmental Delay in Newcomer Children
- Environmental Influences on Prenatal Development
- Factors influencing fetal growth
Prenatal Risk Factors for Developmental Delay in Newcomer Children
Health care providers who see newcomer families have a pivotal role to play in identifying and initiating early treatment for developmental disabilities. Developmental disabilities may last a lifetime but early recognition of their existence, a timely diagnosis and an appropriate treatment plan can make a difference for the children and families involved.
When seeing newcomer families, recognize that risk factors are cumulative. In many parts of the world, suboptimal conditions and care during pregnancy and childbirth can have a range of impacts on developmental health. Developmental disabilities in immigrant and refugee children do not always have a known cause. Common prenatal and perinatal risk factors to consider when taking a patient or family history are reviewed here.
Information and approaches for conducting a culturally sensitive patient history are available on this website. Preconceptional causes of developmental disability relate predominantly to genetic disorders or malformation syndromes.
Genetic disorders are the most commonly identified causal factor for intellectual and other disabilities, and include single gene disorders, multifactorial and polygenic disorders, and chromosomal abnormalities.
Genetic disorders associated with developmental delay include aneuploidies and inborn errors of metabolism. Consanguinity increases the prevalence of rare genetic disorders and significantly increases the risk for intellectual disability and serious birth anomalies, especially in first cousins. Some ethnic communities e. Causes of intellectual disability can be divided into the following categories, listed here with their associated prevalence: 1.
When taking a patient history for a newcomer child with signs of developmental disability, health care providers need to consider the following infections, and screen accordingly.
Women who are pregnant and new to Canada must be screened for HIV, syphilis and rubella. Children younger than 14 years of age are rarely screened for HIV before arriving in Canada, and may not have been tested even if their mother was known to be infected. Maternal HIV increases the risks for prematurity and being small for gestational age SGA ; both effects are associated with increased risk of mortality and developmental delay. HIV enters the central nervous system days to weeks after primary exposure.
The virus causes neuronal damage and cell death, leading to progressive encephalopathy with motor disabilities, as well as to microcephaly and brain atrophy, with cognitive and language delays. The effects of being exposed to but not infected by HIV in utero, or of exposure to perinatal antiretroviral therapy, remain unclear. While preliminary U. In the developed world, CMV is the most common congenital viral infection, with an overall prevalence of 0.
More information on hearing screening for newcomer children is available in this resource. Both hearing loss and visual problems can occur in an otherwise asymptomatic infant. CMV is a herpes virus spread by close interpersonal contact with saliva, blood, genital secretions, urine or breast milk.
Maternal transmission to the fetus from a new or reactivated infection can occur at any gestational age but is highest with a primary infection compared to a reactivated infection. CMV occurs more frequently in nonwhites and individuals living in poverty. Congenital toxoplasmosis occurs at a rate of 1. Toxoplasma gondii is a parasite and a food-borne pathogen.
Human infection results from ingesting or handling undercooked or raw meat containing cysts, by direct contact with infected cats or by consuming food or water contaminated by oocytes egg cells from infected cat feces. Higher rates of infection occur in South America, the eastern Mediterranean and parts of Africa. There are an estimated , cases of congenital rubella annually worldwide. Maternal infection during pregnancy transmits the rubella virus to the fetus, causing deafness, congenital cataracts, microcephaly, seizures, intellectual disability, autism, diabetes, and thyroid dysfunction.
Making sure that women new to Canada are screened for rubella and immunized before pregnancy prevents congenital rubella syndrome. Congenital syphilis can cause deafness, microcephaly, intellectual disability and visual impairment through interstitial keratitis. Zika virus has been recognized to be teratogenic and is caused by the bite of primarily Aedes mosquitoes.
Patients themselves are often asymptomatic other than a rash and transmission occurs via blood products, semen and female genital secretions. Congenital Zika syndrome CZS is associated with microcephaly, cerebral atrophy, abnormal cortical development, callosal hypoplasia, diffuse subcortical calcifications, microphthalmia, cataracts, retinal abnormalities and congenital contractures.
CZS should be considered for a child born since onwards with unexplained microcephaly, intracranial calcifications, ventriculomegaly or major CNS abnormality and a maternal history of travel to a Zika endemic country or sexual contact during pregnancy with a male who travelled to a Zika endemic country in the preceding 6 months.
The developing fetal brain is especially vulnerable to environmental toxins. The blood brain barrier is more immature and more permeable to toxins. The rapid growth of the brain during the 2nd trimester is followed by neuronal migration, differentiation, proliferation and pruning throughout early childhood. Growing cells are more vulnerable to toxins as the brain forms over a longer period than other organs.
Maternal smoking during pregnancy increases the risk of placenta previa, placental abruption, and preterm labour. It also has adverse affects on fetal growth. Exposure to alcohol in utero is the most common teratogenic cause of developmental disabilities, including microcephaly, cognitive disability, learning disabilities, ADHD and behavioural challenges.
Maternal exposure to other toxins, including recreational drugs and certain medications e. The amino acid phenylalanine is a neurotoxin to the developing fetal brain.
Untreated PKU, both maternal and postnatal in the infant, causes intellectual disabilities. Once in the body, lead is distributed to the brain, kidney, liver and bones. Storage in teeth and bones accumulates over time and may be remobilized during pregnancy.
Dependent upon level of exposure lead can lead to reduced IQ, behavioural changes such as reduced attention span, increased antisocial behaviour and reduced educational attainment. The most common cause of prenatal mercury poisoning is eating fish and shellfish species known to contain higher levels of mercury during pregnancy. Arsenic is also present in soil, and prenatal exposure is associated from both sources with intellectual disability and developmental delay.
Chronic pesticide exposure in the occupational setting, especially in poor rural populations, is a problem for all workers and particularly hazardous for pregnant women and children who work and live near areas where these chemicals are used.
Prenatal exposure to the pesticide commonly known as DDT is associated with neurodevelopmental delays in early childhood. It persists in the environment for years and accumulates in the food chain and fatty tissues of humans. An apparently hyperactive year-old boy is brought to your office for assessment. The family moved to Canada from Eastern Europe as refugees, and although they have been in Canada for over 6 months, they speak little French or English.
Their boy was reported to be disruptive in class and was thought to have attention-deficit hyperactivity disorder. A routine examination reveals poor vision in his left eye and moderately impaired vision in his right eye. This spurs a funduscopic examination that reveals severe chorioretinitis. Further questioning of the parents reveals that he had been treated for toxoplasmosis for one month when he was 2 years of age. Follow-up investigations confirm the congenital toxoplasmosis diagnosis and severe developmental delay, even when he is tested in his mother tongue.
Illnesses such as diabetes, hypertension, renal disease and autoimmune disorders are associated with complications to pregnancy that can adversely affect a fetus or newborn child. Hypertension, alone or combined with a renal or autoimmune disorder, can cause placental insufficiency and inadequate fetal growth. Figure 1.
Congenital central nervous system anomalies associated with malnutrition occur more frequently in resource-constrained populations and countries.
This risk factor for developmental disability may also be combined with increased exposure to prenatal toxins, infection, alcohol and poorer access to healthcare and screening.
Folic acid deficiency is associated with neural tube defects. More information on folic acid deficiency is available in this resource. Iodine deficiency is considered by the WHO to be the leading and most preventable cause of brain damage worldwide.
Severe deficiency is associated with intellectual disability, growth failure and cretinism. One U. More information on iodine deficiency is available in this resource. Be sure to explore these questions in an open, nonjudgmental way.
The WHO and the Society of Obstetricians and Gynaecologists of Canada define the perinatal period as commencing at 22 weeks gestation and ending 7 days after birth. The inadequate care of immigrant and refugee women in this critical period in much of the developing world puts mothers and children at higher risk for several pregnancy-related complications, such as birth trauma, hypoxia and ischemia, hypoglycemia, hyperbilirubinemia and various serious infections.
In countries where prenatal and obstetrical care are difficult to access, chronic maternal disease and pregnancy-related complications often go undetected. Undiagnosed or untreated Rh isoimmunization is associated with anemia and severe hyperbilirubinemia, and may result in seizures, deafness, cognitive delays and cerebral palsy in infants who survive. Sources: WHO 19 February www. National, regional and worldwide estimates of preterm birth. The Lancet; Risk factors for preterm delivery include: multi-fetal pregnancy, uterine abnormalities, placental bleeding, prenatal drug exposure, chronic maternal illness, hypertensive disorders, chorioamnionitis, prolonged rupture of the membranes and bacterial vaginosis.
Lack of prenatal care, underimmunization and inadequate treatment for maternal infections or other medical issues, including STIs, can all contribute to developmental disabilities in a preterm infant. An estimated 15 million infants are born prematurely each year, approximately 1 in every 10 births.
Within countries, poorer families are at higher risk. Developmental disabilities can reflect a complex constellation of problems in any child, but particularly for newcomer children, where etiology is often unclear. Sometimes a number of pre- and perinatal risk factors are involved, coexisting and having multiple, cumulative effects on developmental outcomes.
Some signs of disability are evident at birth, others present as late as school age. Developmental disabilities occur worldwide. Immigrant and refugees are at higher risk of developmental disabilities, with specific risk factors depending on their country of origin. Health care providers need to be mindful of general risks for all newcomers but also alert to specific patient risks, recognizing the contribution of family, immigration and ethnic history as well.
Prenatal Risk Factors for Developmental Delay in Newcomer Children Key points Developmental disabilities can occur singly or concurrently in one person. Prenatal risk factors include chronic maternal illness, certain maternal infections, toxin exposures and nutritional deficiencies. Risk factors in the perinatal period include pregnancy-related complications, prematurity and low birth weight, and infection exposure during pregnancy or at time of birth.
Lack of access to quality care during pregnancy, delivery and soon after birth can significantly, adversely affect outcomes for both mother and child, including contributing to developmental disabilities. The lack of maternal and child health care is a significant problem in developing countries.
Lack of health insurance and inadequate access to health care for newcomers in Canada could similarly adversely affect health outcomes.
Environmental Influences on Prenatal Development
Relationships of Maternal Amino Acid Blood Levels to Fetal Development K. S.. Moghissi Familial Factors Affecting Fetal Growth Margaret Ounsted.
Factors influencing fetal growth
However, a number of things, usually caused by genetics or environmental problems, can go wrong during this time. Genetics plays a major role in development. In some cases, genetic problems can emerge that may impact both the current and future growth of the developing child in the womb. Environmental variables can also play a major role in prenatal development.
The environment can have an important influence on development, and this also includes the prenatal period. The growth that happens during the nine months of prenatal development is nothing short of astonishing, but this period is also a time of potential vulnerability.
The central nervous system CNS as the most complex human organ is frequently affected. Sometimes exposures cause gross damage to the brain, but subtle effects due to exposures to single and frequently multiple risk factors are much more common. Multiple risk factors with small effects are difficult to unravel and trace back to their individual effect. In the preconception phase, the parental haploid genomes can harbor genetic polymorphisms and molecular genetic or chromosomal aberrations that are associated with variations in CNS functioning of the offspring. The extent to which functionally relevant epigenetic alterations are transmitted via the germ lines is currently a subject of scientific debate.
Health care providers who see newcomer families have a pivotal role to play in identifying and initiating early treatment for developmental disabilities. Developmental disabilities may last a lifetime but early recognition of their existence, a timely diagnosis and an appropriate treatment plan can make a difference for the children and families involved. When seeing newcomer families, recognize that risk factors are cumulative. In many parts of the world, suboptimal conditions and care during pregnancy and childbirth can have a range of impacts on developmental health. Developmental disabilities in immigrant and refugee children do not always have a known cause. Common prenatal and perinatal risk factors to consider when taking a patient or family history are reviewed here. Information and approaches for conducting a culturally sensitive patient history are available on this website.
Jan E. Growth means increase in size due to an increase of existing structural and functional units. Differentiation is a process whereby a relatively simple system is changed into a more complicated one. Differentiation is accomplished by formation of new structures morphologic differentiation and by formation of new chemical compounds chemical differentiation. Development is related to biological systems a process resulting from a selective, time-related switching on and off of genes. In different biological systems, growth and differentiation are closely related. In human biology, it is necessary to specify growth and differentiation of cells, tissues, and organs, the end result being growth and differentiation of human beings.