Editing Preterm birth (section)

==Prevention==
Historically efforts have been primarily aimed to improve survival and health of preterm infants (tertiary intervention). Such efforts, however, have not reduced the incidence of preterm birth. Increasingly primary interventions that are directed at all women, and secondary intervention that reduce existing risks are looked upon as measures that need to be developed and implemented to prevent the health problems of premature infants and children.<ref name=Iams2008>
{{cite journal | vauthors = Iams JD, Romero R, Culhane JF, Goldenberg RL | title = Primary, secondary, and tertiary interventions to reduce the morbidity and mortality of preterm birth | journal = Lancet | volume = 371 | issue = 9607 | pages = 164–175 | date = January 2008 | pmid = 18191687 | doi = 10.1016/S0140-6736(08)60108-7 | s2cid = 8204299 }}</ref> [[Smoking ban]]s are effective in decreasing preterm births.<ref>{{cite journal | vauthors = Been JV, Nurmatov UB, Cox B, Nawrot TS, van Schayck CP, Sheikh A | title = Effect of smoke-free legislation on perinatal and child health: a systematic review and meta-analysis | journal = Lancet | volume = 383 | issue = 9928 | pages = 1549–1560 | date = May 2014 | pmid = 24680633 | doi = 10.1016/S0140-6736(14)60082-9 | s2cid = 8532979 }}</ref> Different strategies are used in the administration of prenatal care, and future studies need to determine if the focus can be on screening for high-risk women, or widened support for low-risk women, or to what degree these approaches can be merged.<ref name="Iams2008" />

===Before pregnancy===
Adoption of specific professional policies can immediately reduce risk of preterm birth as the experience in assisted reproduction has shown when the number of embryos during embryo transfer was limited.<ref name=Iams2008/>
Many countries have established specific programs to protect pregnant women from hazardous or night-shift work and to provide them with time for prenatal visits and paid pregnancy-leave. The EUROPOP study showed that preterm birth is not related to type of employment, but to prolonged work (over 42 hours per week) or prolonged standing (over 6 hours per day).<ref>{{cite journal | vauthors = Saurel-Cubizolles MJ, Zeitlin J, Lelong N, Papiernik E, Di Renzo GC, Bréart G | title = Employment, working conditions, and preterm birth: results from the Europop case-control survey | journal = Journal of Epidemiology and Community Health | volume = 58 | issue = 5 | pages = 395–401 | date = May 2004 | pmid = 15082738 | pmc = 1732750 | doi = 10.1136/jech.2003.008029 }}</ref> Also, night work has been linked to preterm birth.<ref>
{{cite journal | vauthors = Pompeii LA, Savitz DA, Evenson KR, Rogers B, McMahon M | title = Physical exertion at work and the risk of preterm delivery and small-for-gestational-age birth | journal = Obstetrics and Gynecology | volume = 106 | issue = 6 | pages = 1279–1288 | date = December 2005 | pmid = 16319253 | doi = 10.1097/01.AOG.0000189080.76998.f8 | s2cid = 19518460 }}</ref> Health policies that take these findings into account can be expected to reduce the rate of preterm birth.<ref name=Iams2008/> Preconceptional intake of [[folic acid]] is recommended to reduce birth defects. There is also some evidence that folic acid supplement preconceptionally (before becoming pregnant) may reduce premature birth.<ref>{{cite journal | vauthors = Li B, Zhang X, Peng X, Zhang S, Wang X, Zhu C | title = Folic Acid and Risk of Preterm Birth: A Meta-Analysis | journal = Frontiers in Neuroscience | volume = 13 | pages = 1284 | date = 2019 | pmid = 31849592 | pmc = 6892975 | doi = 10.3389/fnins.2019.01284 | doi-access = free }}</ref> Reducing [[Smoking and pregnancy|smoking]] is expected to benefit pregnant women and their offspring.<ref name=Iams2008/>

===During pregnancy===

Self-care methods to reduce the risk of preterm birth include proper nutrition, avoiding stress, seeking appropriate medical care, avoiding infections, and the control of preterm birth risk factors (e.g. working long hours while standing on feet, carbon monoxide exposure, domestic abuse, and other factors).<ref>
{{cite journal | vauthors = Lamont RF, Jaggat AN | title = Emerging drug therapies for preventing spontaneous preterm labor and preterm birth | journal = Expert Opinion on Investigational Drugs | volume = 16 | issue = 3 | pages = 337–345 | date = March 2007 | pmid = 17302528 | doi = 10.1517/13543784.16.3.337 | s2cid = 11591970 }}</ref> Reducing physical activity during pregnancy has not been shown to reduce the risk of a preterm birth.<ref>{{cite journal | vauthors = Johnston M, Landers S, Noble L, Szucs K, Viehmann L | collaboration = Section on Breastfeeding | title = Prediction and Prevention of Spontaneous Preterm Birth: ACOG Practice Bulletin Summary, Number 234 | journal = Obstetrics and Gynecology | volume = 138 | issue = 2 | pages = 320–323 | date = August 2021 | pmid = 34293768 | doi = 10.1097/AOG.0000000000004480 | s2cid = 236200411 }}</ref> Healthy eating can be instituted at any stage of the pregnancy including nutritional adjustments and consuming suggested vitamin supplements.<ref name=Iams2008/> Calcium supplementation in women who have low dietary calcium may reduce the number of negative outcomes including preterm birth, pre-eclampsia, and maternal death.<ref>{{cite journal | vauthors = Hofmeyr GJ, Lawrie TA, Atallah ÁN, Torloni MR | title = Calcium supplementation during pregnancy for preventing hypertensive disorders and related problems | journal = The Cochrane Database of Systematic Reviews | volume = 2018 | issue = 10 | pages = CD001059 | date = October 2018 | pmid = 30277579 | pmc = 6517256 | doi = 10.1002/14651858.CD001059.pub5 }}</ref> The World Health Organization (WHO) suggests 1.5–2&nbsp;g of calcium supplements daily, for pregnant women who have low levels of calcium in their diet.<ref>{{cite book |title=Guideline: Calcium supplementation in pregnant women |date=2013 |publisher=World Health Organization |location=Geneva}}</ref> Supplemental intake of C and E vitamins have not been found to reduce preterm birth rates.<ref>{{cite journal | vauthors = Rumbold AR, Crowther CA, Haslam RR, Dekker GA, Robinson JS | title = Vitamins C and E and the risks of preeclampsia and perinatal complications | journal = The New England Journal of Medicine | volume = 354 | issue = 17 | pages = 1796–1806 | date = April 2006 | pmid = 16641396 | doi = 10.1056/NEJMoa054186 | hdl = 2440/23161 | doi-access = free | hdl-access = free }}</ref>

While periodontal infection has been linked with preterm birth, [[Randomized controlled trial|randomized trials]] have not shown that periodontal care during pregnancy reduces preterm birth rates.<ref name="Iams2008" /> [[Smoking cessation]] has also been shown to reduce the risk.<ref>{{cite journal | vauthors = Avşar TS, McLeod H, Jackson L | title = Health outcomes of smoking during pregnancy and the postpartum period: an umbrella review | journal = BMC Pregnancy and Childbirth | volume = 21 | issue = 1 | pages = 254 | date = March 2021 | pmid = 33771100 | pmc = 7995767 | doi = 10.1186/s12884-021-03729-1 | doi-access = free }}</ref> The use of personal at home uterine monitoring devices to detect contractions and possible preterm births in women at higher risk of having a preterm baby have been suggested.<ref name="Urquhart_2017">{{cite journal | vauthors = Urquhart C, Currell R, Harlow F, Callow L | title = Home uterine monitoring for detecting preterm labour | journal = The Cochrane Database of Systematic Reviews | volume = 2017 | issue = 2 | pages = CD006172 | date = February 2017 | pmid = 28205207 | pmc = 6464057 | doi = 10.1002/14651858.CD006172.pub4 }}</ref> These home monitors may not reduce the number of preterm births, however, using these devices may increase the number of unplanned antenatal visits and may reduce the number of babies admitted to special care when compared with women receiving normal [[antenatal care]].<ref name="Urquhart_2017" /> Support from medical professionals, friends, and family during pregnancy may be beneficial at reducing caesarean birth and may reduce prenatal hospital admissions; however, these social supports alone may not prevent preterm birth.<ref name="East2019">{{cite journal | vauthors = East CE, Biro MA, Fredericks S, Lau R | title = Support during pregnancy for women at increased risk of low birthweight babies | journal = The Cochrane Database of Systematic Reviews | volume = 2019 | issue = 4 | pages = CD000198 | date = April 2019 | pmid = 30933309 | pmc = 6443020 | doi = 10.1002/14651858.CD000198.pub3 }}</ref>

====Screening during pregnancy====
Screening for asymptomatic bacteriuria followed by appropriate treatment reduces pyelonephritis and reduces the risk of preterm birth.<ref>
{{cite journal | vauthors = Romero R, Oyarzun E, Mazor M, Sirtori M, Hobbins JC, Bracken M | title = Meta-analysis of the relationship between asymptomatic bacteriuria and preterm delivery/low birth weight | journal = Obstetrics and Gynecology | volume = 73 | issue = 4 | pages = 576–582 | date = April 1989 | pmid = 2927852 }}</ref> Extensive studies have been carried out to determine if other forms of screening in low-risk women followed by appropriate intervention are beneficial, including screening for and treatment of ''[[Ureaplasma urealyticum]]'', group B streptococcus, ''[[Trichomonas vaginalis]]'', and bacterial vaginosis did not reduce the rate of preterm birth.<ref name="Iams2008" /> Routine ultrasound examination of the length of the cervix may identify women at risk of preterm labour and tentative evidence suggests ultrasound measurement of the length of the cervix in those with preterm labor can help adjust management and results in the extension of pregnancy by about four days.<ref>{{cite journal | vauthors = Berghella V, Saccone G | title = Cervical assessment by ultrasound for preventing preterm delivery | journal = The Cochrane Database of Systematic Reviews | volume = 2019 | issue = 9 | pages = CD007235 | date = September 2019 | pmid = 31553800 | pmc = 6760928 | doi = 10.1002/14651858.CD007235.pub4 }}</ref> Screening for the presence of fibronectin in vaginal secretions is not recommended at this time in women at low risk of preterm birth.{{Medical citation needed|date=August 2021}}

===Reducing existing risks===
Women are identified to be at increased risk for preterm birth on the basis of their past obstetrical history or the presence of known risk factors. Preconception intervention can be helpful in selected patients in a number of ways. Patients with certain uterine anomalies may have a surgical correction (i.e. removal of a [[uterine septum]]), and those with certain medical problems can be helped by optimizing medical therapies prior to conception, be it for asthma, diabetes, hypertension, and others.

====Multiple pregnancies====
In [[multiple pregnancy|multiple pregnancies]], which often result from use of [[assisted reproductive technology]], there is a high risk of preterm birth. [[Selective reduction]] is used to reduce the number of fetuses to two or three.<ref name=ACOG2017>{{cite web |title=Opinion Number 719: Multifetal Pregnancy Reduction |url=https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Ethics/Multifetal-Pregnancy-Reduction |publisher=American College of Obstetricians and Gynecologists' Committee on Ethics. |date=September 2017 |access-date=26 October 2018 |archive-date=4 April 2019 |archive-url=https://web.archive.org/web/20190404072926/https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Ethics/Multifetal-Pregnancy-Reduction |url-status=dead }}</ref><ref name=Zipori2017>{{cite journal | vauthors = Zipori Y, Haas J, Berger H, Barzilay E | title = Multifetal pregnancy reduction of triplets to twins compared with non-reduced triplets: a meta-analysis | journal = Reproductive Biomedicine Online | volume = 35 | issue = 3 | pages = 296–304 | date = September 2017 | pmid = 28625760 | doi = 10.1016/j.rbmo.2017.05.012 | doi-access = free }}</ref><ref name=Evans2014>{{cite journal | vauthors = Evans MI, Andriole S, Britt DW | title = Fetal reduction: 25 years' experience | journal = Fetal Diagnosis and Therapy | volume = 35 | issue = 2 | pages = 69–82 | year = 2014 | pmid = 24525884 | doi = 10.1159/000357974 | doi-access = free }}</ref>

====Reducing indicated preterm birth====
A number of agents have been studied for the secondary prevention of indicated preterm birth. Trials using low-dose [[aspirin]], [[fish oil]], vitamin C and E, and calcium to reduce preeclampsia demonstrated some reduction in preterm birth only when low-dose aspirin was used.<ref name=Iams2008/> Even if agents such as calcium or [[antioxidant]]s were able to reduce preeclampsia, a resulting decrease in preterm birth was not observed.<ref name=Iams2008/>

====Reducing spontaneous preterm birth====
Reduction in activity by the mother—pelvic rest, limited work, bed rest—may be recommended although there is no evidence it is useful with some concerns it is harmful.<ref>{{cite journal | vauthors = McCall CA, Grimes DA, Lyerly AD | title = "Therapeutic" bed rest in pregnancy: unethical and unsupported by data | journal = Obstetrics and Gynecology | volume = 121 | issue = 6 | pages = 1305–1308 | date = June 2013 | pmid = 23812466 | doi = 10.1097/aog.0b013e318293f12f | s2cid = 9069311 }}</ref> Increasing medical care by more frequent visits and more education has not been shown to reduce preterm birth rates.<ref name="East2019"/> Use of nutritional supplements such as omega-3 [[polyunsaturated fatty acid]]s is based on the observation that populations who have a high intake of such agents are at low risk for preterm birth, presumably as these agents inhibit production of proinflammatory cytokines. A randomized trial showed a significant decline in preterm birth rates,<ref>
{{cite journal | vauthors = Olsen SF, Secher NJ, Tabor A, Weber T, Walker JJ, Gluud C | title = Randomised clinical trials of fish oil supplementation in high risk pregnancies. Fish Oil Trials In Pregnancy (FOTIP) Team | journal = BJOG | volume = 107 | issue = 3 | pages = 382–395 | date = March 2000 | pmid = 10740336 | doi = 10.1111/j.1471-0528.2000.tb13235.x | s2cid = 30837582 | doi-access = free }}</ref> and further studies are in the making.

=====Antibiotics=====

While antibiotics can get rid of bacterial vaginosis in pregnancy, this does not appear to change the risk of preterm birth.<ref>{{cite journal | vauthors = Brocklehurst P, Gordon A, Heatley E, Milan SJ | title = Antibiotics for treating bacterial vaginosis in pregnancy | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD000262 | date = January 2013 | pmid = 23440777 | pmc = 4164464 | doi = 10.1002/14651858.CD000262.pub4 }}</ref> It has been suggested that chronic chorioamnionitis is not sufficiently treated by antibiotics alone (and therefore they cannot ameliorate the need for preterm delivery in this condition).<ref name=Iams2008/>

=====Progestogens=====

[[Progestogen]]s—often given in the form of vaginal<ref>{{cite web |date=July 2017|title=Progesterone: Use in the second and third trimester of pregnancy for the prevention of preterm birth|url=https://ranzcog.edu.au/RANZCOG_SITE/media/RANZCOG-MEDIA/Women%27s%20Health/Statement%20and%20guidelines/Clinical-Obstetrics/Progesterone-use-in-the-second-and-third-trimester-(C-Obs-29b)-Review-July-2017.pdf?ext=.pdf|access-date=2021-01-29|website=The Royal Australian and New Zealand College of Obstetricians and Gynaecologists}}</ref> [[progesterone (medication)|progesterone]] or [[hydroxyprogesterone caproate]]—relax the uterine musculature, maintain cervical length, and possess anti-inflammatory properties; all of which invoke physiological and anatomical changes considered to be beneficial in reducing preterm birth. Two meta-analyses demonstrated a reduction in the risk of preterm birth in women with recurrent preterm birth by 40–55%.<ref>{{cite journal | vauthors = Dodd JM, Jones L, Flenady V, Cincotta R, Crowther CA | title = Prenatal administration of progesterone for preventing preterm birth in women considered to be at risk of preterm birth | journal = The Cochrane Database of Systematic Reviews | volume = 2015 | issue = 7 | pages = CD004947 | date = July 2013 | pmid = 23903965 | doi = 10.1002/14651858.CD004947.pub3 | s2cid = 43862120 | pmc = 11035916 }}</ref><ref>
{{cite journal | vauthors = Mackenzie R, Walker M, Armson A, Hannah ME | title = Progesterone for the prevention of preterm birth among women at increased risk: a systematic review and meta-analysis of randomized controlled trials | journal = American Journal of Obstetrics and Gynecology | volume = 194 | issue = 5 | pages = 1234–1242 | date = May 2006 | pmid = 16647905 | doi = 10.1016/j.ajog.2005.06.049 }}</ref>

Progestogen supplementation also reduces the frequency of preterm birth in pregnancies where there is a short cervix.<ref name="Iams2014">{{cite journal | vauthors = Iams JD | title = Clinical practice. Prevention of preterm parturition | journal = The New England Journal of Medicine | volume = 370 | issue = 3 | pages = 254–261 | date = January 2014 | pmid = 24428470 | doi = 10.1056/NEJMcp1103640 | s2cid = 29480873 }}</ref> A short cervix is one that is less than 25mm, as detected during a transvaginal cervical length assessment in the midtrimester.<ref>{{cite journal | vauthors = Romero R, Nicolaides KH, Conde-Agudelo A, O'Brien JM, Cetingoz E, Da Fonseca E, Creasy GW, Hassan SS | display-authors = 6 | title = Vaginal progesterone decreases preterm birth ≤ 34 weeks of gestation in women with a singleton pregnancy and a short cervix: an updated meta-analysis including data from the OPPTIMUM study | journal = Ultrasound in Obstetrics & Gynecology | volume = 48 | issue = 3 | pages = 308–317 | date = September 2016 | pmid = 27444208 | pmc = 5053235 | doi = 10.1002/uog.15953 }}</ref> However, progestogens are not effective in all populations, as a study involving twin gestations failed to see any benefit.<ref>{{cite journal |vauthors=Caritis S, Rouse D |year=2006 |title=A randomized controlled trial of 17-hydroxyprogesterone caproate (17-OHPC) for the prevention of preterm birth in twins |journal=[[American Journal of Obstetrics & Gynecology]] |volume=195 |issue=6 |pages=S2 |doi=10.1016/j.ajog.2006.10.003 |url=https://zenodo.org/record/1258694 |doi-access=free }}</ref> Despite extensive research related to progestogen effectiveness, uncertainties remain concerning types of progesterone and routes of administration.<ref>{{cite journal | vauthors = Stewart LA, Simmonds M, Duley L, Dietz KC, Harden M, Hodkinson A, Llewellyn A, Sharif S, Walker R, Wright K | display-authors = 6 | title = Evaluating progestogens for prevention of preterm birth international collaborative (EPPPIC) individual participant data (IPD) meta-analysis: protocol | journal = Systematic Reviews | volume = 6 | issue = 1 | pages = 235 | date = November 2017 | pmid = 29183399 | pmc = 5706301 | doi = 10.1186/s13643-017-0600-x | doi-access = free }}</ref>

=====Cervical cerclage=====

In preparation for [[childbirth]], the woman's [[cervix]] shortens. Preterm cervical shortening is linked to preterm birth and can be detected by ultrasonography. [[Cervical cerclage]] is a surgical intervention that places a suture around the cervix to prevent its shortening and widening. Numerous studies have been performed to assess the value of cervical cerclage and the procedure appears helpful primarily for women with a short cervix and a history of preterm birth.<ref name=Iams2014/><ref>
{{cite journal | vauthors = Berghella V, Odibo AO, To MS, Rust OA, Althuisius SM | title = Cerclage for short cervix on ultrasonography: meta-analysis of trials using individual patient-level data | journal = Obstetrics and Gynecology | volume = 106 | issue = 1 | pages = 181–189 | date = July 2005 | pmid = 15994635 | doi = 10.1097/01.AOG.0000168435.17200.53 | s2cid = 22742373 }}</ref> Instead of a prophylactic cerclage, women at risk can be monitored during pregnancy by sonography, and when shortening of the cervix is observed, the cerclage can be performed.<ref name=Iams2008/>