Editing Fellatio (section)

===Pregnancy and semen exposure===
{{See also|Paternal tolerance}}

Fellatio cannot result in [[pregnancy]], as there is no way for ingested [[sperm]] to reach the [[uterus]] and [[fallopian tube]]s to fertilize an [[egg cell]]. At any rate, acids in the stomach and [[digestive enzyme]]s in the [[gastrointestinal tract]] break down and kill spermatozoa.

Clinical research has tentatively linked fellatio with immune modulation,<ref name="Robertson2001">{{Cite journal |last1=Robertson |first1=Sarah A |last2=Ingman |first2=Wendy V |last3=O'Leary |first3=Sean |last4=Sharkey |first4=David J |last5=Tremellen |first5=Kelton P |date=1 October 2002 |title=Transforming growth factor β—a mediator of immune deviation in seminal plasma |url=https://www.sciencedirect.com/science/article/pii/S0165037802000153 |journal=Journal of Reproductive Immunology |volume=57 |issue=1 |pages=109–128 |doi=10.1016/S0165-0378(02)00015-3 |pmid=12385837 |issn=0165-0378}}</ref> indicating it may reduce the chance of complications during pregnancy. The potentially fatal complication [[pre-eclampsia]] was observed to occur less in women who regularly engaged in fellatio, with those who also ingested their partner's semen being at the least risk.<ref>{{cite journal |last1=Koelman |year=2000 |title=Correlation between oral sex and a low incidence of preeclampsia: A role for soluble HLA in seminal fluid? |journal=Journal of Reproductive Immunology |volume=46 |pages=155–166 |doi=10.1016/S0165-0378(99)00062-5 |pmid=10706945 |first1=CA |issue=2 |url=https://research.rug.nl/en/publications/79065d3c-9efc-4a5d-a084-8fca0c46c6aa |display-authors=etal}}</ref> The results were consistent with the fact that semen contains [[TGF beta 1|TGF-β1]], the exchange of which between partners has a causal reduction in risk of pre-eclampsia caused by an [[immunological]] reaction. However, fellatio is not the only viable mechanism for the transmission of TGF-β1.<ref name="Robertson2001" /><ref name="Taylor1997">{{Cite journal |last=Taylor |first=Robert N. |date=January 1997 |title=Review: Immunobiology of Preeclampsia |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1600-0897.1997.tb00195.x |journal=American Journal of Reproductive Immunology |language=en |volume=37 |issue=1 |pages=79–86 |doi=10.1111/j.1600-0897.1997.tb00195.x |pmid=9138457 |s2cid=42576690 |issn=1046-7408}}</ref><ref name="Chaouat2005">{{Cite journal |last1=Chaouat |first1=Gérard |last2=Robillard |first2=Pierre-Yves |last3=Dekker |first3=Gustaaf |date=1 October 2005 |title=Fourth International Workshop on Immunology of Pre-eclampsia, December 2004, Reunion, France |url=https://www.sciencedirect.com/science/article/pii/S0165037805001385 |journal=Journal of Reproductive Immunology |series=Proceedings of Post-Congress Kyoto Symposium |volume=67 |issue=1 |pages=103–111 |doi=10.1016/j.jri.2005.09.004 |pmid=16315347 |issn=0165-0378}}</ref>