Scientists are fascinated by twins. Even though twins are born at the same time and generally raised under similar circumstances they still may develop differently. For their research on inequality between girls and boys in developing countries, researchers Jeroen Smits (Radboud University Nijmegen) and Christiaan Monden (University of Oxford) determined how many twins were born in 76 developing countries.
This new information is now published in the scientific journal PLoS One.
Sociologist/economist Jeroen Smits has brought together demographic, socio-economic and health data on millions of households in over one hundred developing countries into one huge database called Database Developing World. The information in this database is being used in various research studies involving inequality. In collaboration with sociologist Christiaan Monden, Smits has used this information to create a twins database for 76 developing countries. The database contains information on approximately 2.5 million births by 1.4 million women. This information was collected between 1987 and 2010 in 150 large household surveys. The purpose of the twins database is to study inequalities between girls and boys in terms of education, infant mortality, health and related factors.
The twins database is therefore a means, not an end. Until now, little was known about twinning rates in developing countries. The information that was available was generally derived from hospital registrations, which are notorious for their selectivity problems: as twin births are associated with more complications, these births tends to be overrepresented among hospital births. Hospital records therefore do not provide a good picture of the national situation.
High twinning rate in Central Africa, low rate in Asia
Further research The researchers do not provide an explanation for the vast differences in twin birth rates among the different regions of the developing world. The literature reveals that genetics plays a significant role in twin births and substantial differences have been perceived in the twinning rates of various ethnic groups. In Nigeria, for example, the number of twins born to Yoruba women is much higher than those born to Hausa women. In the United States, more twins are born to women of African descent than to women of European descent. Differences in the age at which women get their children and in the number of pregnancies they experience also play a role. Older women more often get twins than younger women and in a fourth or fifth pregnancy, the chances of getting a twin are higher than in a first or second pregnancy. The new twins database offers many opportunities for further research into the causes of the observed differences.
Cite This Page: