Editing Multiple birth (section)

==Risks==
===Premature birth and low birth weight===
Babies born from multiple-birth pregnancies are much more likely to result in [[premature birth]] than those from single pregnancies. 51% of twins and 91% of triplets are born preterm, compared to 9.4% in singletons.<ref name="Alexander-1998">{{Cite journal |vauthors=Alexander GR, Kogan M, Martin J, Papiernik E |date=March 1998 |title=What are the fetal growth patterns of singletons, twins, and triplets in the United States? |journal=Clin Obstet Gynecol |volume=41 |issue=1 |pages=114–25 |doi=10.1097/00003081-199803000-00017 |pmid=9504230}} {{clear}}''Note: This study was done by looking at the 1991–1995 U.S. Natality Files, which were received from the National Center for Health Statistics''</ref> 14% of twins and 41% of triplets are even born ''very preterm'', compared to 1.7% in singletons.<ref name="Alexander-1998" />

Drugs known as betamimetics can be used to relax the muscles of the uterus and delay birth in singleton pregnancies.<ref>{{Cite journal |last1=Neilson |first1=JP |last2=West |first2=HM |last3=Dowswell |first3=T |date=5 February 2014 |title=Betamimetics for inhibiting preterm labour. |journal=The Cochrane Database of Systematic Reviews |volume=2014 |issue=2 |pages=CD004352 |doi=10.1002/14651858.CD004352.pub3 |pmc=10603219 |pmid=24500892}}</ref> There is some evidence that these drugs can also reduce the risk of preterm birth for twin pregnancies, but existing studies are small. More data is required before solid conclusions can be drawn.<ref>{{Cite journal |last1=Yamasmit |first1=W |last2=Chaithongwongwatthana |first2=S |last3=Tolosa |first3=JE |last4=Limpongsanurak |first4=S |last5=Pereira |first5=L |last6=Lumbiganon |first6=P |date=8 December 2015 |title=Prophylactic oral betamimetics for reducing preterm birth in women with a twin pregnancy. |journal=The Cochrane Database of Systematic Reviews |volume=2015 |issue=12 |pages=CD004733 |doi=10.1002/14651858.CD004733.pub4 |pmc=7386823 |pmid=26645888}}</ref> Likewise, existing studies are too small to determine if a [[Cervical cerclage|cervical suture]] is effective for reducing prematurity in cases of multiple birth.<ref>{{Cite journal |last1=Rafael |first1=TJ |last2=Berghella |first2=V |last3=Alfirevic |first3=Z |date=10 September 2014 |title=Cervical stitch (cerclage) for preventing preterm birth in multiple pregnancy. |journal=The Cochrane Database of Systematic Reviews |volume=2014 |issue=9 |pages=CD009166 |doi=10.1002/14651858.CD009166.pub2 |pmc=10629495 |pmid=25208049 |s2cid=205198527}}</ref>

As a result of [[preterm birth]], multiples tend to have [[lower birth weight]] than singletons. Exceptions are possible, however, as with the Kupresak triplets, born in 2008 in [[Mississauga]], [[Ontario]], Canada. Their combined weight was 17 lbs, 2.7 oz, which set a world record. Two of the triplets were similar in size and, as expected, moderately low birth weight. The two combined weighed 9 lbs, 2.7 oz. The third triplet, however, was much larger and weighed 8 lbs. individually.<ref>{{Cite news |last=Le |first=Julia |date=26 July 2011 |title=Triplets set world record |url=https://www.mississauga.com/community-story/3118996-triplets-set-world-record/ |access-date=1 September 2021 |work=Mississauga News |location=Mississauga ON}} {{clear}}''Note: Record was not confirmed until July 2011''</ref>

===Cerebral palsy===
[[Cerebral palsy]] is more common among multiple births than single births, being 2.3 per 1,000 survivors in singletons, 13 in twins, and 45 in triplets in [[North West England]].<ref>{{Cite journal |vauthors=Pharoah PO, Cooke T |year=1996 |title=Cerebral palsy and multiple births |journal=Arch. Dis. Child. Fetal Neonatal Ed. |volume=75 |issue=3 |pages=F174–7 |doi=10.1136/fn.75.3.f174 |pmc=1061194 |pmid=8976682}}{{clear}}''Note: Study looked at the registered births of babies born with cerebral palsy during the periods of 1982-1989 in the counties of Merseyside and Cheshire.''</ref> This is likely a side effect of premature birth and low birth weight.

=== Behavioral issues ===
Premature birth is associated with a higher risk for a breadth of behavioral and socioemotional difficulties that begin in childhood and continue through [[teenagehood]] and often into adulthood. Conditions where the risk is greatest include [[attention deficit hyperactivity disorder]], [[Autism spectrum|autism spectrum disorder]], and anxiety disorders.<ref>{{Cite web |title=Multiple Birth: Twins, Triplets, Complications & Symptoms |url=https://my.clevelandclinic.org/health/articles/9710-expecting-twins-or-triplets |access-date=2023-04-13 |website=Cleveland Clinic |language=en}}</ref>

===Incomplete separation===
{{Further|Twin#Degree of separation}}
Multiples may be [[monochorionic]], sharing the same [[chorion]], with resultant risk of [[twin-to-twin transfusion syndrome]]. Monochorionic multiples may even be [[monoamniotic]], sharing the same [[amniotic sac]], resulting in risk of [[umbilical cord compression]] and [[nuchal cord]]. In very rare cases, there may be [[conjoined twins]], possibly impairing function of internal organs.

===Mortality rate (stillbirth)===
Multiples are also known to have a higher mortality rate.  It is more common for multiple births to be stillborn, while for singletons the risk is not as high.  A literary review on multiple pregnancies shows a study done on one set each of septuplets and octuplets, two sets of sextuplets, 8 sets of quintuplets, 17 sets of quadruplets, and 228 sets of triplets.  By doing this study, Hammond found that the mean gestational age (how many weeks when birthed) at birth was 33.4 weeks for triplets and 31 weeks for quadruplets. This shows that stillbirth happens usually 3–5 weeks before the woman reaches full term and also that for sextuplets or higher it almost always ends in death of the fetuses.<ref>{{Cite journal |last=Hammond KR |year=1998 |title=Multifetal pregnancy reduction |journal=J Obstet Gynecol Neonatal Nurs |volume=27 |issue=3 |pages=338–43 |doi=10.1111/j.1552-6909.1998.tb02657.x |pmid=9620827}}</ref>
Though multiples are at a greater risk of being stillborn, there is inconclusive evidence whether the actual mortality rate is higher in multiples than in singletons.

===Prevention in IVF===
Today many multiple pregnancies are the result of [[in vitro fertilisation]] (IVF). In a 1997 study of 2,173 [[embryo transfer]]s performed as part of [[in vitro fertilisation]] (IVF), 34% were successfully delivered pregnancies.<ref name="Elsner-1997">{{Cite journal |vauthors=Elsner CW, Tucker MJ, Sweitzer CL, Brockman WD, Morton PC, Wright G, Toledo AA |year=1997 |title=Multiple pregnancy rate and embryo number transferred during in vitro fertilization |journal=Am. J. Obstet. Gynecol. |volume=177 |issue=2 |pages=350–355; discussion 355–357 |doi=10.1016/S0002-9378(97)70197-2 |pmid=9290450}}</ref> The overall multiple pregnancy rate was 31.3% (24.7% twins, 5.8% triplets, and .08% quadruplets).<ref name="Elsner-1997" /> Because IVFs are producing more multiples, a number of efforts are being made to reduce the risk of multiple births- specifically triplets or more. Medical practitioners are doing this by limiting the number of embryos per embryo transfer to one or two. That way, the risks for the mother and fetuses are decreased.

The appropriate number of embryos to be transferred depends on the age of the woman, whether it is the first, second or third full IVF cycle attempt and whether there are top-quality embryos available. According to a guideline from The [[National Institute for Health and Care Excellence]] (NICE) in 2013, the number of embryos transferred in a cycle should be chosen as in following table:<ref name="Fertility">{{Cite web |date=February 2013 |title=Fertility: assessment and treatment for people with fertility problems |url=http://guidance.nice.org.uk/CG156 |url-status=live |archive-url=https://web.archive.org/web/20130223023043/http://guidance.nice.org.uk/CG156 |archive-date=2013-02-23 |access-date=2024-03-31 |website=National Institute for Health and Care Excellence (NICE) guidelines |ref=NICE clinical guideline CG156}}</ref>

{|class="wikitable"
|-
! Age !! Attempt no. !! Embryos transferred
|-
|rowspan=3| <37 years || 1st || 1
|-
| 2nd || 1 if top-quality
|-
| 3rd || No more than 2
|-
|rowspan=3| 37–39 years ||rowspan=2| 1st & 2nd || 1 if top-quality
|-
| 2 if not top-quality
|-
| 3rd || No more than 2
|-
| 40–42 years ||  || 2
|}

Also, it is recommended to use single embryo transfer in all situations if a top-quality blastocyst is available.<ref name="Fertility" />