Frequency of twinning in Kwara State, North-Central Nigeria

Twin birth prevalence varies widely among the world population. Several factors such as genetic, maternal, socio-economic and environmental have been implicated in its incidence. Although these factors are still the subject of a number of investigations variations do exist in the reported incidence of twinning across the world. There is limited information on the frequency of twinning in Kwara state, North Central Nigeria. This study aims to determine the frequency and prevalence of twinning in Kwara state of the North Central Nigeria. We wish to update the current knowledge on the trend and frequency of twinning in North-Central Nigeria and thereby contributing to the demographic studies in the country. We carried out an 11-year retrospective study on the incidence of twin births between 1998 and 2008. Data were collected from the University of Ilorin Teaching Hospital, Ilorin (UITH), Omosebi Hospital, Ilorin (OHI) and Erinle General Hospital, Erinle (EGHE) all in Kwara state, North-Central Nigeria. These data were pooled together and analyzed by year and maternal age groups of 15–19, 20–24, 25–29, 30–34, 35–39, 40–44, and 45–49years according to the standard method. Frequencies of twin births of 37.60, 35.01, and 35.9 per 1000 deliveries were recorded for UITH, OHI and EGHE respectively. The overall average frequency of 37.4 per 1000 deliveries for the three hospitals was recorded in the study. The maternal age group of 25–29years had the highest occurrence of twin births (35.33%), while the lowest was recorded in the 45–49years age group (1.32%). This study shows that there is an increase in twinning rate in the Kwara state when compared with previous reports on this subject matter. This is probably due to an increase in awareness and use of ovulation stimulating drugs or multiple embryo transfers among women.