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Study Question: How many twins are born in human populations and how has this changed over recent decades?Summary Answer: Since the 1980s, the global twinning rate has increased by a third, from 9.1 to 12.0 twin deliveries per 1000 deliveries, to about 1.6 million twin pairs each year.What Is Known Already: It was already known that in the 1980s natural twinning rates were low in (East) Asia and South America, at an intermediate level in Europe and North America, and high in many African countries. It was also known that in recent decades, twinning rates have been increasing in the wealthier parts of our world as a result of the rise in medically assisted reproduction (MAR) and delayed childbearing.Study Design, Size, Duration: We have brought together all information on national twinning rates available from statistical offices, demographic research institutes, individual survey data and the medical literature for the 1980-1985 and the 2010-2015 periods.Participants/materials, Setting, Methods: For 165 countries, covering over 99% of the global population, we were able to collect or estimate twinning rates for the 2010-2015 period. For 112 countries, we were also able to obtain twinning rates for 1980-1985.Main Results and the Role Of Chance: Substantial increases in twinning rates were observed in many countries in Europe, North America and Asia. For 74 out of 112 countries the increase was more than 10%. Africa is still the continent with highest twinning rates, but Europe, North America and Oceania are catching up rapidly. Asia and Africa are currently home to 80% of all twin deliveries in the world.Limitations, Reasons For Caution: For some countries, data were derived from reports and papers based on hospital registrations which are less representative for the country as a whole than data based on public administrations and national surveys.Wider Implications Of the Findings: The absolute and relative number of twins for the world as a whole is peaking at an unprecedented level. An important reason for this is the tremendous increase in medically assisted reproduction in recent decades. This is highly relevant, as twin deliveries are associated with higher infant and child mortality rates and increased complications for mother and child during pregnancy and during and after delivery.Study Funding/competing Interest(s): The contribution of CM was partially supported by the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Programme (grant No 681546, FAMSIZEMATTERS), Nuffield College, and the Leverhulme Trust. The contribution of GP was partially supported by the French Agence Nationale de la Recherche (grant No ANR-18-CE36-0007-07). The authors declare no conflict of interest.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Background: Non-communicable diseases (NCDs) remain a major challenge in the 21st century. High-income countries (HICs) populations are ethnically and culturally diverse due to international migration. Evidence suggests that NCDs rates differ between migrants and the host populations in HICs. This paper presents a review of NCDs burden among migrant groups in HICs in Europe, North America and Australia with a major focus on cardiovascular diseases (CVDs), cancer and diabetes.Methods: We performed a narrative review consisting of scholarly papers published between 1960 until 2018.Results: CVD risk differs by country of origin, country of destination and duration of residence. For example, stroke is more common in sub-Sahara African and South-Asian migrants, but lower in North African and Chinese migrants. Chinese migrants, however, have a higher risk of haemorrhagic stroke despite the lower rate of overall stroke. Coronary heart disease (CHD) is more common in South-Asian migrants, but less common in sub-Saharan and north African migrants although the lower risk of CHD in these population is waning. Diabetes risk is higher in all migrants and migrants seem to develop diabetes at an earlier age than the host populations. Migrants in general have lower rates of overall cancer morbidity and mortality than the host populations in Europe. However, migrants have a higher infectious disease-related cancers than the host populations in Europe. In North America, the picture is more complex. Data from cross-national comparisons indicate that migration-related lifestyle changes associated with the lifestyle of the host population in the country of settlement may influence NCDs risk among migrants in a very significant way.Conclusion: With exception of diabetes, which is consistently higher in all migrant groups than in the host populations, the burden of NCDs among migrants seems to depend on the migrant group, country of settlement and NCD type. This suggests that more work is needed to disentangle the key migration-related lifestyle changes and contextual factors that may be driving the differential risk of NCDs among migrants in order to assist prevention and clinical management of NCDs in these populations. [ABSTRACT FROM AUTHOR]

Previews the Africa-Europe Group for Inter-disciplinary Studies (AEGIS) European Conference on African Studies to be held on June 29-July 3, 2005 in London, England. Estimated number of panel discussions to be held; Call for papers to be presented in the conference; Contact information.