Editing Language delay (section)

===Natural/medical factors===
'''Hearing loss'''

The process of children acquiring language skills involves hearing sounds and words from their caregivers and surroundings. Hearing loss causes that lack of these sound inputs, causing these children to have difficulties learning to use and understand language, which will eventually lead to delayed speech and language skills.<ref>{{cite web|url=https://www.asha.org/public/hearing/effects-of-hearing-loss-on-development/|title=Effects of Hearing Loss on Development|website=asha.org|access-date=31 March 2021}}</ref>  For example, they may struggle with putting sentences together, understanding speech from other people or using the correct grammar,<ref>{{cite web|url=https://www.cincinnatichildrens.org/health/h/hearing-communication#:~:text=Hearing%20loss%20can%20affect%20a,understanding%20and%20talking%20very%20difficult|title=Hearing Loss: How it affects Communication|website=cincinnatichildrens.org|access-date=31 March 2021}}</ref> which are some language skills that typically developing children possess.

'''Autism'''

There is strong evidence that [[autism]] is commonly associated with language delay.<ref name="pmid166085442">{{cite journal|vauthors=Miniscalco C, Nygren G, Hagberg B, Kadesjö B, Gillberg C|title=Neuropsychiatric and neurodevelopmental outcome of children at age 6 and 7 years who screened positive for language problems at 30 months|journal=Developmental Medicine and Child Neurology|volume=48|issue=5|pages=361–6|date=May 2006|pmid=16608544|doi=10.1017/S0012162206000788|s2cid=23692745|hdl=2077/851|doi-access=free |hdl-access=free}}</ref><ref name="pmid197130732">{{cite journal|vauthors=Hagberg BS, Miniscalco C, Gillberg C|title=Clinic attenders with autism or attention-deficit/hyperactivity disorder: cognitive profile at school age and its relationship to preschool indicators of language delay|journal=Research in Developmental Disabilities|volume=31|issue=1|pages=1–8|year=2010|pmid=19713073|doi=10.1016/j.ridd.2009.07.012 }}</ref>  Children with autism may have difficulties in developing language skills and understanding what is being said to them. They may also have troubles communicating non-verbally by using hand gestures, eye contact and facial expressions.<ref name=":27" /> The extent of their language usage is heavily influenced by their intellectual and social developments. The range of their skills can be very different and on opposite ends of a spectrum. Many children with autism develop some speech and language skills, but not like typically developing children, and with uneven progress.<ref name=":27">{{cite web|url=https://www.nidcd.nih.gov/health/autism-spectrum-disorder-communication-problems-children|title=Autism Spectrum Disorder: Communication Problems in Children|website=nidcd.nih.gov|date=13 April 2020 |access-date=31 March 2021}}</ref>

[[Asperger syndrome]], which is classified under the broad umbrella term of autistic spectrum disorder, however, is not associated with language delay.<ref name="DSM-IV-TR-299.002">{{cite book|title=Diagnostic and statistical manual of mental disorders: DSM-IV|author=American Psychiatric Association|publisher=American Psychiatric Association|year=2000|isbn=0-89042-025-4|edition=4|location=Washington, DC|chapter=Diagnostic criteria for 299.00 Autistic Disorder|oclc=768475353|chapter-url=http://cdc.gov/ncbddd/autism/hcp-dsm.html}}</ref> Children diagnosed with Asperger syndrome have decent language skills but use language in different ways from others. They may not be able to understand the use of language devices, such as irony and humor, or conversation reciprocity between involved parties.<ref>{{cite web|url=https://www.autism-society.org/what-is/aspergers-syndrome/|title=Asperger's Syndrome|website=autism-society.org|access-date=31 March 2021}}</ref>

'''Heritability'''

[[Gene]]s have a very big influence in the presence of language impairments.<ref>{{cite journal|vauthors=Bishop DV, North T, Donlan C|title=Genetic basis of specific language impairment: evidence from a twin study|journal=Developmental Medicine and Child Neurology|volume=37|issue=1|pages=56–71|date=January 1995|pmid=7828787|doi=10.1111/j.1469-8749.1995.tb11932.x|s2cid=21594745 }}</ref> Neurobiological and genetic mechanisms have a strong influence on late language emergence. A child with a family history of language impairments is more likely to have delayed language emergence and persistent language impairments.<ref>{{cite journal|vauthors=Lyytinen P, Poikkeus AM, Laakso ML, Eklund K, Lyytinen H|title=Language development and symbolic play in children with and without familial risk for dyslexia|journal=Journal of Speech, Language, and Hearing Research|volume=44|issue=4|pages=873–85|date=August 2001|pmid=11521780|doi=10.1044/1092-4388(2001/070) }}</ref> They are also 2 times more likely to be late talkers as compared to those with no such family history.<ref>{{cite journal|vauthors=Zubrick SR, Taylor CL, Rice ML, Slegers DW|title=Late language emergence at 24 months: an epidemiological study of prevalence, predictors, and covariates|journal=Journal of Speech, Language, and Hearing Research|volume=50|issue=6|pages=1562–92|date=December 2007|pmid=18055773|pmc=3521638|doi=10.1044/1092-4388(2007/106) }}</ref>

[[genetic disorder|Genetic abnormalities]] may also be a cause of language delays. In 2005, researchers found a connection between expressive language delay and a genetic abnormality: a duplicate set of the same genes that are missing in individuals with [[Williams-Beuren syndrome]]. Also so called [[XYY syndrome]] can often cause speech delay.<ref>{{Cite web|url=https://medlineplus.gov/genetics/condition/47xyy-syndrome/|title=47,XYY syndrome: MedlinePlus Genetics|website=medlineplus.gov}}</ref>

'''Twins'''

Being a twin increases the chance of speech and language delays. Reasons for this are thought to include less one-on-one time with parents, the premature birth of twins, and the companionship of their twin sibling reducing their motivation to talk to others.<ref>{{Cite news|url=https://twinpickle.com/2017/11/07/do-twins-talk-to-each-other/|title=Do Twins Talk to Each Other in a Secret Language?|date=2017-11-07|work=Twin Pickle|access-date=2018-03-06|language=en}}</ref>{{more citations needed|date=July 2022}} A [[twin study]] has also shown that [[Genetics|genetic]] factors have an important role in language delay. [[Monozygotic twin]] pairs (identical twins) recorded a higher consistency than [[dizygotic twin]] (fraternal twins) pairs, revealing monozygotic twins experiencing early vocabulary delay is attributed to genetic etiology.<ref name=":28">{{cite journal|vauthors=Bishop DV, Price TS, Dale PS, Plomin R|title=Outcomes of early language delay: II. Etiology of transient and persistent language difficulties|language=en|journal=Journal of Speech, Language, and Hearing Research|volume=46|issue=3|pages=561–75|date=June 2003|pmid=14696986|doi=10.1044/1092-4388(2003/045) }}</ref> The environmental factors that influences both twins also play a big role in causing early language delay, but only when it is transient.<ref name=":28" />

'''Gender'''

Research has shown that boys are at greater risk for delayed language development than girls.<ref name=":29">{{cite web|url=https://www.sciencedaily.com/releases/2014/02/140217085246.htm|title=Gender, genes play an important role in delayed language development|website=sciencedaily|access-date=31 March 2021}}</ref> Almost all developmental disorders that affect communication, speech and language skills are more common in males than in females.<ref>{{cite journal|vauthors=Adani S, Cepanec M|title=Sex differences in early communication development: behavioral and neurobiological indicators of more vulnerable communication system development in boys|journal=Croatian Medical Journal|volume=60|issue=2|pages=141–149|date=April 2019|pmid=31044585|pmc=6509633|doi=10.3325/cmj.2019.60.141 }}</ref> British scientists have found that the male sex hormone ([[testosterone]]) levels were related to the development of both autism and language disorders, which explains why boys are at a greater risk of developmental disorders biologically.<ref name=":29" />

'''Perinatal conditions'''

There is a high prevalence of early language delay among toddlers with [[palsy|neonatal brachial plexus palsy]].<ref name=":31">{{cite journal|vauthors=Chang KW, Yang LJ, Driver L, Nelson VS|title=High prevalence of early language delay exists among toddlers with neonatal brachial plexus palsy|journal=Pediatric Neurology|volume=51|issue=3|pages=384–9|date=September 2014|pmid=25160543|pmc=4792271|doi=10.1016/j.pediatrneurol.2014.04.021 }}</ref> Hand usage and gestures are part of the [[motor system]] and have been proven correlate to comprehension and production aspects in language development. An interruption in the hand/arm usage caused by this condition during stages of language development could possibly cause these children to experience language delays.<ref name=":31" />

Stress during pregnancy is associated with language delay.<ref name="pmid173553982">{{cite journal|vauthors=Talge NM, Neal C, Glover V|title=Antenatal maternal stress and long-term effects on child neurodevelopment: how and why?|journal=Journal of Child Psychology and Psychiatry, and Allied Disciplines|volume=48|issue=3–4|pages=245–61|year=2007|pmid=17355398|doi=10.1111/j.1469-7610.2006.01714.x |pmc=11016282}}</ref> High levels of prenatal stress can result in poorer general intellectual and language outcomes.<ref>{{cite journal|vauthors=Laplante DP, Barr RG, Brunet A, Galbaud du Fort G, Meaney ML, Saucier JF, Zelazo PR, King S|display-authors=6|title=Stress during pregnancy affects general intellectual and language functioning in human toddlers|journal=Pediatric Research|volume=56|issue=3|pages=400–10|date=September 2004|pmid=15240860|doi=10.1203/01.PDR.0000136281.34035.44|s2cid=13333204|doi-access=free }}</ref> Chemical exposure during pregnancy may also be a factor that causes language delays.<ref>{{cite journal|vauthors=Repouskou A, Papadopoulou AK, Panagiotidou E, Trichas P, Lindh C, Bergman Å, Gennings C, Bornehag CG, Rüegg J, Kitraki E, Stamatakis A|display-authors=6|title=Long term transcriptional and behavioral effects in mice developmentally exposed to a mixture of endocrine disruptors associated with delayed human neurodevelopment|journal=Scientific Reports|volume=10|issue=1|pages=9367|date=June 2020|pmid=32518293|pmc=7283331|doi=10.1038/s41598-020-66379-x|doi-access=free|bibcode=2020NatSR..10.9367R }}</ref>