Editing Microcephaly (section)

===Historical causes of microcephaly===

After the dropping of [[atomic bombs]] "Little Boy" on [[Hiroshima]] and "Fat Man" on [[Nagasaki]], several women close to [[ground zero]] who had been pregnant at the time gave birth to children with microcephaly.<ref>{{cite web|url=http://www.pcf.city.hiroshima.jp/kids/KPSH_E/hiroshima_e/sadako_e/subcontents_e/13kousyougai_1_e.html#|title=Aftereffects|archive-url=https://web.archive.org/web/20090525013355/http://www.pcf.city.hiroshima.jp/kids/KPSH_E/hiroshima_e/sadako_e/subcontents_e/13kousyougai_1_e.html|archive-date=2009-05-25|url-status=live}}</ref> Microcephaly was present in 7 children from a group of 11 pregnant women at 11–17 weeks of [[gestation]] who survived the blast at less than {{convert|1.2|km|mi|abbr=on}} from ground zero.<ref name=Kalter10>{{cite book |chapter=Pioneering Studies §Atomic Radiation §Microcephaly and Mental Retardation |chapter-url={{GBUrl|DykKlVU0V-oC|pg=PA21}}|title=Teratology in the Twentieth Century Plus Ten|last1=Kalter|first1=Harold|date=2010 |publisher=Springer |isbn=978-90-481-8820-8 |page=21 |doi=10.1007/978-90-481-8820-8_2}}</ref> Due to their proximity to the bomb, the pregnant women's ''[[Uterus|in utero]]'' children received a [[Relative biological effectiveness|biologically significant radiation dose]] that was relatively high due to the massive [[neutron]] output of the lower explosive-yielding [[Little Boy]].<ref name=Kalter10/> Researchers studied 286 additional children who were in utero during the atomic bombings, and after a year they found these children had a higher incidence of microcephaly and mental retardation.<ref>{{Cite journal|last1=Burrow|first1=Gerard N.|last2=Hamilton|first2=Howard B.|last3=Hrubec|first3=Zdenek|date=June 1964|title=Study of Adolescents Exposed in Utero to the Atomic Bomb, Nagasaki, Japan|journal=[[Yale Journal of Biology and Medicine]]|volume=36|issue=6|pages=430–444 |pmc=2604646|pmid=14173443}}</ref><ref name=Kalter10/>