Editing Morning sickness (section)

==Cause==

The cause of morning sickness is unknown but may relate to changing levels of estrogen and the hormone [[human chorionic gonadotropin]].<ref name=Fes2009/><ref name=":0">{{cite journal |vauthors=Viljoen E, Visser J, Koen N, Musekiwa A |date=March 2014 |title=A systematic review and meta-analysis of the effect and safety of ginger in the treatment of pregnancy-associated nausea and vomiting |journal=[[Nutrition Journal]] |type=Systematic review; meta-analysis<!-- from title and pubmed --> |volume=13 |pages=20 |doi=10.1186/1475-2891-13-20 |pmc=3995184 |pmid=24642205 |doi-access=free}}</ref> Some have proposed that morning sickness may be useful from an [[evolutionary]] point of view -it may protect both the pregnant woman and the developing embryo just when the fetus is most vulnerable.<ref name=ACOG2015Full/> Diagnosis should only occur after other possible causes have been ruled out.<ref name=ACOG2015/> [[Abdominal pain]], fever, or [[headache]]s are typically not present in morning sickness.<ref name=ACOG2015Full/>

Nausea and vomiting may also occur with [[molar pregnancy]].<ref>{{cite journal | vauthors = Verberg MF, Gillott DJ, Al-Fardan N, Grudzinskas JG | title = Hyperemesis gravidarum, a literature review | journal = Human Reproduction Update | volume = 11 | issue = 5 | pages = 527–539 | date = 2005 | pmid = 16006438 | doi = 10.1093/humupd/dmi021 | doi-access = free }}</ref>

Morning sickness is related to diets low in cereals and high in sugars, oilcrops, alcohol and meat.<ref name = "Pepper_2006">{{cite journal | vauthors = Pepper GV, Craig Roberts S | title = Rates of nausea and vomiting in pregnancy and dietary characteristics across populations | journal = Proceedings. Biological Sciences | volume = 273 | issue = 1601 | pages = 2675–2679 | date = October 2006 | pmid = 17002954 | pmc = 1635459 | doi = 10.1098/rspb.2006.3633 }}</ref>