The review found that the fate of twins in low and middle-income countries was more of a concern. In sub-Saharan Africa, in particular, many twins will lose their co-twin in their first year of life - more than 200,000 each year. "While twinning rates in many rich Western countries are now getting close to those in sub-Saharan Africa, there is a huge difference in the survival chances," said Prof Jeroen Smits, a study author. Looking ahead, the researchers say India and China will play a major role in future twinning rates. Declining fertility, older mothers at birth and techniques like IVF will all have a bearing on the numbers of twins in years to come.
