Table of ContentsView AllTable of ContentsUltrasoundRisksCarrying to TermIdentical Features
Table of ContentsView All
View All
Table of Contents
Ultrasound
Risks
Carrying to Term
Identical Features
Identical twinsthat share aplacenta(the fetal organ providing oxygen and nutrients to the fetus during pregnancy) and anamnioticsac (a fluid-filled sac surrounding the fetus in-utero) are calledmonochorionic-monoamnioticor mono mono twins. This happens in about 0.1% of all pregnancies and 1% oftwin pregnancies.
Learn about mono mono twins, potential complications when two fetuses share a placenta and amniotic sac, carrying to term, and more.
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Mono Mono Twins on Ultrasound
Anultrasoundduring the first trimester ofpregnancyis up to 98% accurate in determining if twins share a placenta and amniotic sac.However, it can be difficult to tell if twins are mono mono before the ninth week of pregnancy. This is important to know to monitor for possible pregnancy complications.
Since the placenta and amniotic sac are shared, all mono mono twins are identical twins, meaning they share the same genes and originate from the same egg, which split into two after fertilization.
Risks of Carrying Mono Mono Twins
The risks are higher for mono mono twin pregnancies than for other twin pregnancies. The survival rate for mono mono twins is 70%. However, healthcare providers can offer guidance to improve outcomes and reduce the risk of complications. This is why it is crucial to determine if the fetuses share a placenta and amniotic sac in the first trimester of pregnancy.
Risks associated with mono mono twin pregnancies include:
Regularly see a healthcare professional such as anobstetrician-gynecologist (ob-gyn)whenever pregnancy, twin pregnancy, or monochorionic-monoamniotic twin pregnancy is suspected or discovered.With monitoring and care, risks associated with mono mono twin pregnancies can be prevented and treated.
Carrying Mono Mono Twins to Term
It is possible to carry mono mono twins and deliver healthy babies. While there are increased risks, the survival rate after 24 weeks ofgestationmay be as high as 97%.It is best to seek care early in pregnancy and to continue monitoring throughout pregnancy so that any possible complications are diagnosed and treated as early as possible.
Mono mono twins are typically delivered between 33 and 34 weeks to treat current complications and prevent additional complications from occurring later in pregnancy. Some mono mono twins are born vaginally, though most are delivered via Cesarean section (C-section).The timing and mode of delivery depend on the health of the gestational carrier, fetal health, and pregnancy progression.
Identical Features of Mono Mono Twins
In identical twins, the egg splits into two after fertilization, so the genes of both fetuses are the same.They may not look the same, but they will always be the same sex, both girls or boys. Because they have the samegenes, they are more likely to look the same compared to fraternal twins or non-multiple siblings, but they can develop differently throughout pregnancy. For example, one may be noticeably bigger than the other, and their fingerprints are not the same.
Summary
Mono mono twins are a rare type of identical twins that share one placenta and amniotic sac. An ultrasound done in the first trimester of pregnancy is the best way to determine if you are carrying mono mono twins.
The survival rate for mono mono twins is 70%, meaning there is an increased risk compared to people pregnant with one fetus or twins with separate placentas and amniotic sacs. Mono mono twins are generally delivered between 33 and 34 weeks to treat and prevent complications. If you are carrying mono mono twins, attending all of your appointments and working closely with a healthcare provider to monitor and reduce the risk of complications is crucial.
5 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Columbia University Department of Obstetrics and Gynecology.Monoamniotic twins.Jha P, Morgan TA, Kennedy A.US evaluation of twin pregnancies: Importance of chorionicity and amnionicity.RadioGraphics. 2019;39(7):2146-2166. doi:10.1148/rg.2019190042NIH National Human Genome Institute.Identical twins.Van Mieghem T, Abbasi N, Shinar S, et al.Monochorionic monoamniotic twin pregnancies.American Journal of Obstetrics & Gynecology MFM. 2022;4(2):100520. doi:10.1016/j.ajogmf.2021.100520Söderhult I, Tiblad E, Herling L.Perinatal outcome in monoamniotic twin pregnancies during a 10-year period: a single center, descriptive study.Arch Gynecol Obstet. 2022;307(1):233-239. doi:10.1007/s00404-022-06506-3
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Columbia University Department of Obstetrics and Gynecology.Monoamniotic twins.Jha P, Morgan TA, Kennedy A.US evaluation of twin pregnancies: Importance of chorionicity and amnionicity.RadioGraphics. 2019;39(7):2146-2166. doi:10.1148/rg.2019190042NIH National Human Genome Institute.Identical twins.Van Mieghem T, Abbasi N, Shinar S, et al.Monochorionic monoamniotic twin pregnancies.American Journal of Obstetrics & Gynecology MFM. 2022;4(2):100520. doi:10.1016/j.ajogmf.2021.100520Söderhult I, Tiblad E, Herling L.Perinatal outcome in monoamniotic twin pregnancies during a 10-year period: a single center, descriptive study.Arch Gynecol Obstet. 2022;307(1):233-239. doi:10.1007/s00404-022-06506-3
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Columbia University Department of Obstetrics and Gynecology.Monoamniotic twins.Jha P, Morgan TA, Kennedy A.US evaluation of twin pregnancies: Importance of chorionicity and amnionicity.RadioGraphics. 2019;39(7):2146-2166. doi:10.1148/rg.2019190042NIH National Human Genome Institute.Identical twins.Van Mieghem T, Abbasi N, Shinar S, et al.Monochorionic monoamniotic twin pregnancies.American Journal of Obstetrics & Gynecology MFM. 2022;4(2):100520. doi:10.1016/j.ajogmf.2021.100520Söderhult I, Tiblad E, Herling L.Perinatal outcome in monoamniotic twin pregnancies during a 10-year period: a single center, descriptive study.Arch Gynecol Obstet. 2022;307(1):233-239. doi:10.1007/s00404-022-06506-3
Columbia University Department of Obstetrics and Gynecology.Monoamniotic twins.
Jha P, Morgan TA, Kennedy A.US evaluation of twin pregnancies: Importance of chorionicity and amnionicity.RadioGraphics. 2019;39(7):2146-2166. doi:10.1148/rg.2019190042
NIH National Human Genome Institute.Identical twins.
Van Mieghem T, Abbasi N, Shinar S, et al.Monochorionic monoamniotic twin pregnancies.American Journal of Obstetrics & Gynecology MFM. 2022;4(2):100520. doi:10.1016/j.ajogmf.2021.100520
Söderhult I, Tiblad E, Herling L.Perinatal outcome in monoamniotic twin pregnancies during a 10-year period: a single center, descriptive study.Arch Gynecol Obstet. 2022;307(1):233-239. doi:10.1007/s00404-022-06506-3
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