Editing Miscarriage (section)

===Anatomical defects and trauma===
Fifteen per cent of women who have experienced three or more recurring miscarriages have some anatomical defect that prevents the pregnancy from being carried for the entire term.{{sfn|Hoffman|page=181}} The structure of the uterus affects the ability to carry a child to term. Anatomical differences are common and can be congenital.<ref>{{Cite journal |last1=Qian |first1=Liang |last2=Ding |first2=Jiashan |last3=Shi |first3=Lan |last4=Yu |first4=Qing |last5=Zhu |first5=Jiawei |last6=Huang |first6=Anfeng |date=2023-12-04 |title=Analysis of hemi-uterus pregnancy outcomes in uterine malformations: a retrospective observational study |journal=BMC Pregnancy and Childbirth |volume=23 |issue=1 |pages=836 |doi=10.1186/s12884-023-06136-w |doi-access=free |pmid=38049742 |pmc=10696795 |issn=1471-2393}}</ref>
{| class="wikitable"
!Type of uterine<br>structure
!Miscarriage rate<br>associated with defect
!References
|-
|[[Bicornate uterus]]
|40–79%
|{{sfn|Hoffman|page=181–182}}<ref name="auto7"/>
|-
|[[Septate uterus|Septate]] or [[Unicornuate uterus|unicornate]]
|34–88%
|{{sfn|Hoffman|page=181–182}}
|-
|[[Arcuate uterus|Arcuate]]
|Unknown
|{{sfn|Hoffman|page=181–182}}
|-
|[[Uterus didelphys|Didelphys]]
|40%
|{{sfn|Hoffman|page=181–182}}
|-
|[[Uterine fibroid|Fibroids]]
|Unknown
|<ref name="NHS-Miscarriage-Causes"/>
|-
|}

In some women, [[cervical incompetence]] or cervical insufficiency occurs with the inability of the cervix to stay closed during the entire pregnancy.<ref name="American College of Obstetricians and 372–9"/><ref name="NHS-Miscarriage-Causes"/> It does not cause first-trimester miscarriages. In the second trimester, it is associated with an increased risk of miscarriage. It is identified after a premature birth has occurred at about 16–18 weeks into the pregnancy.{{sfn|Hoffman|page=181}} During the second trimester, major trauma can result in a miscarriage.{{sfn|Hoffman|page=172}}