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<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="ru"><front><journal-meta><journal-id journal-id-type="publisher-id">usfd</journal-id><journal-title-group><journal-title xml:lang="ru">Ультразвуковая и функциональная диагностика</journal-title><trans-title-group xml:lang="en"><trans-title>Ultrasound &amp; Functional Diagnostics</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">1607-0771</issn><issn pub-type="epub">2408-9494</issn><publisher><publisher-name>Vidar Ltd.</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.24835/1607-0771-272</article-id><article-id custom-type="elpub" pub-id-type="custom">usfd-272</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>Ультразвуковая диагностика в акушерстве и гинекологии</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="en"><subject>Obstetrics and Gynecology Ultrasound</subject></subj-group></article-categories><title-group><article-title>Ультразвуковая оценка сердечной деятельности эмбриона как прогностический критерий неблагоприятного исхода беременности</article-title><trans-title-group xml:lang="en"><trans-title>Ultrasound assessment of embryo cardiac function as a predictive criterion of adverse pregnancy outcome</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0009-0000-2412-628X</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Тимакина</surname><given-names>Д. Н.</given-names></name><name name-style="western" xml:lang="en"><surname>Timakina</surname><given-names>D. N.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Тимакина Дарья Николаевна – главный врач ООО “Хороший доктор”; врач высшей категории, врач ультразвуковой диагностики обособленного подразделения “Женская консультация №2” ГБУЗ города Москвы “ГКБ имени Ф.И. Иноземцева ДЗ города Москвы”, Москваhttps://orcid.org/0009-0000-2412-628X </p></bio><bio xml:lang="en"><p>Darya N. Timakina – M.D., Head of Good Doctor LLC; ultrasound diagnostics doctor of  Maternity Welfare Center №2, F.I. Inozemtsev City Clinical Hospital of Moscow Healthcare Department, Moscowhttps://orcid.org/0009-0000-2412-628X </p></bio><email xlink:type="simple">drtimakina@gmail.com</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0000-0001-8295-768X</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Буланов</surname><given-names>М. Н.</given-names></name><name name-style="western" xml:lang="en"><surname>Bulanov</surname><given-names>M. N.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Буланов Михаил Николаевич – доктор мед. наук, заведующий отделением ультразвуковой диагностики ГБУЗ ВО “Областная клиническая больница”, Владимир; профессор кафедры внутренних болезней Института медицинского образования ФГБОУ ВО “Новгородский государственный университет имени Ярослава Мудрого”, Великий Новгородhttps://orcid.org/0000-0001-8295-768X </p></bio><bio xml:lang="en"><p>Mikhail N. Bulanov – Doct. of Sci. (Med.), Head of Ultrasound Diagnostics Department, Regional Clinical Hospital, Vladimir; Professor, Division of Internal Medicine, Institute of Medical Education, Yaroslav-the-Wise Novgorod State University, Veliky Novgorodhttps://orcid.org/0000-0001-8295-768X</p></bio><email xlink:type="simple">doctorbulanov@gmail.com</email><xref ref-type="aff" rid="aff-2"/></contrib><contrib contrib-type="author" corresp="yes"><contrib-id contrib-id-type="orcid">https://orcid.org/0009-0009-2432-381X</contrib-id><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Ефремов</surname><given-names>В. А.</given-names></name><name name-style="western" xml:lang="en"><surname>Efremov</surname><given-names>V. A.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Ефремов Владимир Анатольевич – канд. физ.-мат. наук, научный сотрудник НИИ прикладной информатики и математической геофизики ФГАОУ ВО “Балтийский федеральный университет имени Иммануила Канта”, Калининградhttps://orcid.org/0009-0009-2432-381X</p></bio><bio xml:lang="en"><p>Vladimir A. Efremov – Cand. of Sci. (Phys.-Math.), researcher, Scientific Research Institute of Applied Informatics and Mathematical Geophysics, Immanuel Kant Baltic Federal University, Kaliningradhttps://orcid.org/0009-0009-2432-381X </p></bio><email xlink:type="simple">clinicgooddoctor@gmail.com</email><xref ref-type="aff" rid="aff-3"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru">ГБУЗ города Москвы “ГКБ имени Ф.И. Иноземцева ДЗ города Москвы”; &#13;
ООО “Хороший доктор”, Москва<country>Россия</country></aff><aff xml:lang="en">F.I. Inozemtsev City Clinical Hospital of Moscow Healthcare Department; 2 Good Doctor Clinic, Moscow<country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-2"><aff xml:lang="ru">ГБУЗ Владимирской области “Областная клиническая больница”,  Владимир;&#13;
ФГБОУ ВПО “Новгородский государственный университет имени Ярослава Мудрого”, Великий Новгород<country>Россия</country></aff><aff xml:lang="en">Regional Clinical Hospita, Vladimir; &#13;
Yaroslav-the-Wise Novgorod State University, Veliky Novgorod<country>Russian Federation</country></aff></aff-alternatives><aff-alternatives id="aff-3"><aff xml:lang="ru">ФГАОУ ВО “Балтийский федеральный университет имени Иммануила Канта”, Калининград<country>Россия</country></aff><aff xml:lang="en">Immanuel Kant Baltic Federal University, Kaliningrad<country>Russian Federation</country></aff></aff-alternatives><pub-date pub-type="collection"><year>2024</year></pub-date><pub-date pub-type="epub"><day>02</day><month>10</month><year>2024</year></pub-date><volume>0</volume><issue>3</issue><fpage>61</fpage><lpage>74</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Тимакина Д.Н., Буланов М.Н., Ефремов В.А., 2024</copyright-statement><copyright-year>2024</copyright-year><copyright-holder xml:lang="ru">Тимакина Д.Н., Буланов М.Н., Ефремов В.А.</copyright-holder><copyright-holder xml:lang="en">Timakina D.N., Bulanov M.N., Efremov V.A.</copyright-holder><license license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://usfd.vidar.ru/jour/article/view/272">https://usfd.vidar.ru/jour/article/view/272</self-uri><abstract><sec><title>Цель исследования</title><p>Цель исследования: изучение значимости частоты сердечных сокращений (ЧСС) эмбриона/плода в ранние сроки беременности при ультразвуковом исследовании для формирования группы высокого риска неблагоприятного исхода беременности.</p></sec><sec><title>Материал и методы</title><p>Материал и методы. Проведен ретроспективный анализ ультразвуковых исследований 1073 беременных в 5+0–10+6 нед. ЧСС эмбриона/плода сопоставляли со сроком беременности, рассчитанным по копчико-теменному размеру (КТР) и по дате последней менструации. Ретроспективно обследованные беременные разделены на 2 группы: 1-я группа – с внутриутробной гибелью эмбриона до 14 нед беременности (n = 107); 2-я группа – с пролонгированием беременности до II триместра (n = 966). При обработке массива данных с помощью дерева решений ЧСС эмбриона оценивалась в различные сроки беременности по дате последней менструации, по КТР, а также без учета точного срока беременности.</p></sec><sec><title>Результаты</title><p>Результаты. Анализ значений ЧСС в разные сроки беременности по последней менструации показал достоверность отличий ЧСС между группами, причем для позднее погибших эмбрионов оказалось характерным снижение ЧСС. Отсутствовали достоверные различия ЧСС между группами в разные сроки беременности, рассчитанные по КТР (достоверные различия наблюдались только в 8+0–9+6 нед). Для прогноза неблагоприятного исхода беременности предложены пороговые значения ЧСС для различных сроков беременности, а также универсальное пороговое значение ЧСС для всего эмбрионального периода.</p></sec><sec><title>Выводы</title><p>Выводы. Использование предложенных пороговых значений ЧСС эмбриона для разных сроков беременности, рассчитанных по дате последней менструации, может быть эффективно использовано для своевременного прогноза неблагоприятного исхода беременности. Когда неизвестен точный срок беременности, возможно использование универсального порогового значения ЧСС &lt;116 уд/мин. Все предложенные пороговые значения ЧСС имеют высокую специфичность. Ни одно из предложенных пороговых значений ЧСС не имеет высокой чувствительности, повысить которую может его использование в сочетании с другими ультразвуковыми и клиническими маркерами неблагоприятного исхода беременности в эмбриональном периоде.</p></sec></abstract><trans-abstract xml:lang="en"><p>Purpose to evaluate the value of the embryo/fetus heart rate (HR) in early pregnancy assessed by ultrasound for the formation of a group at high risk of adverse pregnancy outcomes.</p><sec><title>Materials and methods</title><p>Materials and methods. A retrospective analysis of ultrasound examinations of 1073 pregnant women at 5+0–10+6 weeks was carried out. The embryo/fetus heart rate was compared with the gestational age calculated by the crown rump length (CRL) and the date of the last menstruation period (LMP). Retrospectively, all examined pregnant women were divided into two groups: group 1—with intrauterine embryo death before 14 weeks of pregnancy (n = 107); group 2—with prolongation of pregnancy until the second trimester (n = 966). When analyzing the data array using a decision tree, the embryo heart rate was assessed at various stages of pregnancy by LMP, CRL, and regardless of the exact period of pregnancy.</p></sec><sec><title>Results</title><p>Results. Analysis of heart rate values at different stages of pregnancy by LMP showed significant differences in heart rate between groups, the cases of later embryo loss characterized by lover heart rate values. There were no significant differences in heart rate between the groups at different stages of pregnancy by CRL (significant differences were obtained only at 8+0–9+6 weeks). Cut-off values of embryo heart rate for prediction of adverse pregnancy outcomes have been proposed for different stages of pregnancy, as well as a universal cut-off for the entire embryonic period.</p></sec><sec><title>Conclusion</title><p>Conclusion. The proposed cut-off values of embryo heart rate for different stages of pregnancy, calculated by LMP, may be used for timely prediction of adverse pregnancy outcomes. When the exact gestational age is unknown, a universal heart rate cut-off value of &lt;116 bpm may be used. All proposed HR cut-off values were characterized by high specificity, but none of them by high sensitivity. A sensitivity of HR cut-off values can be increased by the use in combination with other ultrasound and clinical signs of adverse pregnancy outcome.</p></sec></trans-abstract><kwd-group xml:lang="ru"><kwd>ультразвуковая диагностика</kwd><kwd>неразвивающаяся беременность</kwd><kwd>ультразвуковые маркеры</kwd><kwd>частота сердечных сокращений эмбриона</kwd></kwd-group><kwd-group xml:lang="en"><kwd>ultrasound diagnostics</kwd><kwd>non-developing pregnancy</kwd><kwd>ultrasound markers</kwd><kwd>embryo heart rate</kwd></kwd-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Grisolia G., Milano K., Pilu G. et al. Biometry of early pregnancy with transvaginal sonography. Ultrasound Obstet. Gynecol. 1993; 3 (6): 403–411. https://doi.org/10.1046/j.1469-0705.1993.03060403.x</mixed-citation><mixed-citation xml:lang="en">Grisolia G., Milano K., Pilu G. et al. Biometry of early pregnancy with transvaginal sonography. Ultrasound Obstet. Gynecol. 1993; 3 (6): 403–411. https://doi.org/10.1046/j.1469-0705.1993.03060403.x</mixed-citation></citation-alternatives></ref><ref id="cit2"><label>2</label><citation-alternatives><mixed-citation xml:lang="ru">Акушерство: Национальное руководство. 2-е изд., перераб. и доп. / Под ред. Г.М. Савельевой, Г.Т. Сухих, В.Н. Серова, В.Е. Радзинского. М.:, ГЭОТАР-Медиа, 2022. 1080 с. ISBN 978-5-9704-6632-2</mixed-citation><mixed-citation xml:lang="en">Obstetrics: National guidelines. / Eds Savelieva G.M., Suhih G.T., Serov V.N., Radzinsky V.E. M.: GEOTAR-Media, 2022. 1080 p. ISBN 978-5-9704-6632-2 (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit3"><label>3</label><citation-alternatives><mixed-citation xml:lang="ru">Алтынник Н.А., Медведев М.В. Скрининговое ультразвуковое исследование в 11–14 недель беременности: Учебное пособие. М.: Реал Тайм, 2016: 168–176.</mixed-citation><mixed-citation xml:lang="en">Altynnik N.A., Medvedev M.V. Screening ultrasonic examination at 11–14 weeks of gestation: textbook. M.: Real Time. 2016: 168–176. (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit4"><label>4</label><citation-alternatives><mixed-citation xml:lang="ru">Тимакина Д.Н., Буланов М.Н. Маркеры неблагоприятного исхода беременности при ультразвуковом исследовании в эмбриональном периоде: литературный обзор и собственные клинические наблюдения. Ультразвуковая и функциональная диагностика. 2023; 4: 67–95. https://doi.org/10.24835/1607-0771-2023-4-67-95</mixed-citation><mixed-citation xml:lang="en">Timakina D.N., Bulanov M.N. Ultrasound markers of adverse pregnancy outcomes in embryonal period: literature review and own clinical cases. Ultrasound &amp; Functional Diagnostics. 2023; 4: 67–95. https://doi.org/10.24835/1607-0771-2023-4-67-95 (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit5"><label>5</label><citation-alternatives><mixed-citation xml:lang="ru">Ouyang Y., Qin J., Lin G. et al. Reference intervals of gestational sac, yolk sac, embryonic length, embryonic heart rate at 6–10 weeks after in vitro fertilization-embryo transfer. BMC Pregnancy Childbirth. 2020; 20 (1): 533. https://doi.org/10.1186/s12884-020-03186-2</mixed-citation><mixed-citation xml:lang="en">Ouyang Y., Qin J., Lin G. et al. Reference intervals of gestational sac, yolk sac, embryonic length, embryonic heart rate at 6–10 weeks after in vitro fertilization-embryo transfer. BMC Pregnancy Childbirth. 2020; 20 (1): 533. https://doi.org/10.1186/s12884-020-03186-2</mixed-citation></citation-alternatives></ref><ref id="cit6"><label>6</label><citation-alternatives><mixed-citation xml:lang="ru">Chittacharoen A., Herabutya Y. Slow fetal heart rate may predict pregnancy outcome in first-trimester threatened abortion. Fertil. and Steril. 2004; 82 (1): 227–229. https://doi.org/10.1016/j.fertnstert.2003.12.026</mixed-citation><mixed-citation xml:lang="en">Chittacharoen A., Herabutya Y. Slow fetal heart rate may predict pregnancy outcome in first-trimester threatened abortion. Fertil. and Steril. 2004; 82 (1): 227–229. https://doi.org/10.1016/j.fertnstert.2003.12.026</mixed-citation></citation-alternatives></ref><ref id="cit7"><label>7</label><citation-alternatives><mixed-citation xml:lang="ru">Dede F.S., Ulucay U., Kose M.F. et al. Fetal loss in threatened abortion after demonstration of fetal cardiac activity in a low socioeconomic population. J. Obstet. Gynaecol. 2010; 30 (6): 622–625. https://doi.org/10.3109/01443615.2010.489164</mixed-citation><mixed-citation xml:lang="en">Dede F.S., Ulucay U., Kose M.F. et al. Fetal loss in threatened abortion after demonstration of fetal cardiac activity in a low socioeconomic population. J. Obstet. Gynaecol. 2010; 30 (6): 622–625. https://doi.org/10.3109/01443615.2010.489164</mixed-citation></citation-alternatives></ref><ref id="cit8"><label>8</label><citation-alternatives><mixed-citation xml:lang="ru">El-Mekkawi Sh.F., El-Shanawy H., Alyamni O.M. Prediction of spontaneous miscarriage risk by the use of first trimester ultrasound measurements and maternal serum progesterone level at the 7th week of pregnancy. Middle East Fertility Society Journal. 2015; 20 (1): 16–20. https://doi.org/10.1016/j.mefs.2014.04.006</mixed-citation><mixed-citation xml:lang="en">El-Mekkawi Sh.F., El-Shanawy H., Alyamni O.M. Prediction of spontaneous miscarriage risk by the use of first trimester ultrasound measurements and maternal serum progesterone level at the 7th week of pregnancy. Middle East Fertility Society Journal. 2015; 20 (1): 16–20. https://doi.org/10.1016/j.mefs.2014.04.006</mixed-citation></citation-alternatives></ref><ref id="cit9"><label>9</label><citation-alternatives><mixed-citation xml:lang="ru">Datta M.R., Raut A. Efficacy of first-trimester ultrasound parameters for prediction of early spontaneous abortion. Int. J. Gynaecol. Obstet. 2017; 138 (3): 325–330. https://doi.org/10.1002/ijgo.12231</mixed-citation><mixed-citation xml:lang="en">Datta M.R., Raut A. Efficacy of first-trimester ultrasound parameters for prediction of early spontaneous abortion. Int. J. Gynaecol. Obstet. 2017; 138 (3): 325–330. https://doi.org/10.1002/ijgo.12231</mixed-citation></citation-alternatives></ref><ref id="cit10"><label>10</label><citation-alternatives><mixed-citation xml:lang="ru">Блинов А.Ю., Емельяненко Е.С. Атлас по ультразвуковой диагностике в акушерстве (эхограммы с комментариями): Практическое пособие для врачей. М.: МЕДпресс-информ, 2024. 26 с.</mixed-citation><mixed-citation xml:lang="en">Blinov A.Yu., Emel'yanenko E.S. Atlas po ul'trazvukovoj diagnostike v akusherstve (ekhogrammy s kommentariyami): Prakticheskoe posobie dlya vrachej. M.: MEDpress-inform, 2024. 26 p. (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit11"><label>11</label><citation-alternatives><mixed-citation xml:lang="ru">Taylor T.J., Quinton A.E., de Vries B.S., Hyett J.A. First-trimester ultrasound features associated with subsequent miscarriage: A prospective study. Aust. N. Z. J. Obstet. Gynaecol. 2019; 59 (5): 641–648. https://doi.org/10.1111/ajo.12944</mixed-citation><mixed-citation xml:lang="en">Taylor T.J., Quinton A.E., de Vries B.S., Hyett J.A. First-trimester ultrasound features associated with subsequent miscarriage: A prospective study. Aust. N. Z. J. Obstet. Gynaecol. 2019; 59 (5): 641–648. https://doi.org/10.1111/ajo.12944</mixed-citation></citation-alternatives></ref><ref id="cit12"><label>12</label><citation-alternatives><mixed-citation xml:lang="ru">Sakamoto A., Kamada Y., Kubo K. et al. Slow Fetal Heart Rate before Miscarriage in the Early First Trimester Predicts Fetal Aneuploidy in Women with Recurrent Pregnancy Loss. Acta Med. Okayama. 2018; 72 (1): 61–66. https://doi.org/10.18926/AMO/55664</mixed-citation><mixed-citation xml:lang="en">Sakamoto A., Kamada Y., Kubo K. et al. Slow Fetal Heart Rate before Miscarriage in the Early First Trimester Predicts Fetal Aneuploidy in Women with Recurrent Pregnancy Loss. Acta Med. Okayama. 2018; 72 (1): 61–66. https://doi.org/10.18926/AMO/55664</mixed-citation></citation-alternatives></ref><ref id="cit13"><label>13</label><citation-alternatives><mixed-citation xml:lang="ru">Yi Y., Lu G., Ouyang Y. et al. A logistic model to predict early pregnancy loss following in vitro fertilization based on 2601 infertility patients. Reprod. Biol. Endocrinol. 2016; 14: 15. https://doi.org/10.1186/s12958-016-0147-z</mixed-citation><mixed-citation xml:lang="en">Yi Y., Lu G., Ouyang Y. et al. A logistic model to predict early pregnancy loss following in vitro fertilization based on 2601 infertility patients. Reprod. Biol. Endocrinol. 2016; 14: 15. https://doi.org/10.1186/s12958-016-0147-z</mixed-citation></citation-alternatives></ref><ref id="cit14"><label>14</label><citation-alternatives><mixed-citation xml:lang="ru">Reus A.D., El-Harbachi H., Rousian M. et al. Early first-trimester trophoblast volume in pregnancies that result in live birth or miscarriage. Ultrasound Obstet. Gynecol. 2013; 42 (5): 577–584. https://doi.org/10.1002/uog.13197. PMID: 23996572.</mixed-citation><mixed-citation xml:lang="en">Reus A.D., El-Harbachi H., Rousian M. et al. Early first-trimester trophoblast volume in pregnancies that result in live birth or miscarriage. Ultrasound Obstet. Gynecol. 2013; 42 (5): 577–584. https://doi.org/10.1002/uog.13197. PMID: 23996572.</mixed-citation></citation-alternatives></ref><ref id="cit15"><label>15</label><citation-alternatives><mixed-citation xml:lang="ru">Stamatopoulos N., Lu C., Casikar I. et al. Prediction of subsequent miscarriage risk in women who present with a viable pregnancy at the first early pregnancy scan. Aust. N. Z. J. Obstet. Gynaecol. 2015; 55 (5): 464–472. https://doi.org/10.1111/ajo.12395</mixed-citation><mixed-citation xml:lang="en">Stamatopoulos N., Lu C., Casikar I. et al. Prediction of subsequent miscarriage risk in women who present with a viable pregnancy at the first early pregnancy scan. Aust. N. Z. J. Obstet. Gynaecol. 2015; 55 (5): 464–472. https://doi.org/10.1111/ajo.12395</mixed-citation></citation-alternatives></ref><ref id="cit16"><label>16</label><citation-alternatives><mixed-citation xml:lang="ru">Makrydimas G., Sebire N.J., Lolis D. et al. Fetal loss following ultrasound diagnosis of a live fetus at 6-10 weeks of gestation. Ultrasound Obstet. Gynecol. 2003; 22 (4): 368–372. https://doi.org/10.1002/uog.204</mixed-citation><mixed-citation xml:lang="en">Makrydimas G., Sebire N.J., Lolis D. et al. Fetal loss following ultrasound diagnosis of a live fetus at 6-10 weeks of gestation. Ultrasound Obstet. Gynecol. 2003; 22 (4): 368–372. https://doi.org/10.1002/uog.204</mixed-citation></citation-alternatives></ref><ref id="cit17"><label>17</label><citation-alternatives><mixed-citation xml:lang="ru">Altay M.M., Yaz H., Haberal A. The assessment of the gestational sac diameter, crown-rump length, progesterone and fetal heart rate measurements at the 10th gestational week to predict the spontaneous abortion risk. J. Obstet. Gynaecol. Res. 2009; 35 (2): 287–292. https://doi.org/10.1111/j.1447-0756.2008.00927.x</mixed-citation><mixed-citation xml:lang="en">Altay M.M., Yaz H., Haberal A. The assessment of the gestational sac diameter, crown-rump length, progesterone and fetal heart rate measurements at the 10th gestational week to predict the spontaneous abortion risk. J. Obstet. Gynaecol. Res. 2009; 35 (2): 287–292. https://doi.org/10.1111/j.1447-0756.2008.00927.x</mixed-citation></citation-alternatives></ref><ref id="cit18"><label>18</label><citation-alternatives><mixed-citation xml:lang="ru">Wie J.H., Choe S., Kim S.J. et al. Sonographic Parameters for Prediction of Miscarriage: Role of 3-Dimensional Volume Measurement. J. Ultrasound Med. 2015; 34 (10): 1777–1784. https://doi.org/10.7863/ultra.15.14.09012</mixed-citation><mixed-citation xml:lang="en">Wie J.H., Choe S., Kim S.J. et al. Sonographic Parameters for Prediction of Miscarriage: Role of 3-Dimensional Volume Measurement. J. Ultrasound Med. 2015; 34 (10): 1777–1784. https://doi.org/10.7863/ultra.15.14.09012</mixed-citation></citation-alternatives></ref><ref id="cit19"><label>19</label><citation-alternatives><mixed-citation xml:lang="ru">Тимакина Д.Н., Буланов М.Н., Ефремов В.А. Возможность прогноза ранних пренатальных потерь на основании оценки сердечной деятельности эмбриона в различные сроки беременности. Ультразвуковая и функциональная диагностика. 2018; 3: s41.</mixed-citation><mixed-citation xml:lang="en">Timakina D.N., Bulanov M.N., Efremov V.A. Possibility of early prenatal loss prediction based on assessment of embryo heart function in different gestation terms. Ultrasound and Functional Diagnostics. 2018; 3: s41. (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit20"><label>20</label><citation-alternatives><mixed-citation xml:lang="ru">Тимакина Д.Н., Буланов М.Н., Ефремов В.А. Изучение частоты сердцебиения эмбриона с расчетом порогового значения высокого риска ранних пренатальных потерь без учета точного срока беременности. Ультразвуковая и функциональная диагностика. 2018; 3: s.42</mixed-citation><mixed-citation xml:lang="en">Timakina D.N., Bulanov M.N., Efremov V.A. Study of embryo heart rate with calculation of threshold for high risk of early prenatal losses without taking into account of exact gestation term. Ultrasound and Functional Diagnostics. 2018; 3: s. 42. (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit21"><label>21</label><citation-alternatives><mixed-citation xml:lang="ru">Salvesen K., Abramowicz J., Ter Haar G. et al.; Board of the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). ISUOG statement on the safe use of Doppler for fetal ultrasound examination in the first 13+6 weeks of pregnancy (updated). Ultrasound Obstet. Gynecol. 2021; 57 (6): 1020. https://doi.org/10.1002/uog.23610</mixed-citation><mixed-citation xml:lang="en">Salvesen K., Abramowicz J., Ter Haar G. et al.; Board of the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG). ISUOG statement on the safe use of Doppler for fetal ultrasound examination in the first 13+6 weeks of pregnancy (updated). Ultrasound Obstet. Gynecol. 2021; 57 (6): 1020. https://doi.org/10.1002/uog.23610</mixed-citation></citation-alternatives></ref><ref id="cit22"><label>22</label><citation-alternatives><mixed-citation xml:lang="ru">Hothorn T., Hornik K., Zeileis A. Unbiased Recursive Partitioning: A Conditional Inference Framework. J. Computational Graph. Stat. 2006; 15 (3): 651–674. https://doi.org/10.1198/106186006X133933</mixed-citation><mixed-citation xml:lang="en">Hothorn T., Hornik K., Zeileis A. Unbiased Recursive Partitioning: A Conditional Inference Framework. J. Computational Graph. Stat. 2006; 15 (3): 651–674. https://doi.org/10.1198/106186006X133933</mixed-citation></citation-alternatives></ref><ref id="cit23"><label>23</label><citation-alternatives><mixed-citation xml:lang="ru">Клинические рекомендации. Выкидыш (самопроизвольный аборт). Год утверждения (частота пересмотра): 2021. Разработчик клинической рекомендации Российское общество акушеров-гинекологов. Одобрено Научно-практическим Советом Минздрава РФ.</mixed-citation><mixed-citation xml:lang="en">Clinical guidelines. Miscarriage (spontaneous abortion). Year of approval (revision frequency): 2021. Clinical practice guideline developer - Russian Society of Obstetrician and Gynecologists Approved by the Applied Research Council, Ministry of Health of the Russian Federation. (In Russian)</mixed-citation></citation-alternatives></ref><ref id="cit24"><label>24</label><citation-alternatives><mixed-citation xml:lang="ru"></mixed-citation><mixed-citation xml:lang="en"></mixed-citation></citation-alternatives></ref></ref-list><fn-group><fn fn-type="conflict"><p>The authors declare that there are no conflicts of interest present.</p></fn></fn-group></back></article>
