Twinning and its correlates: community-based study in a rural area of India.

A retrospective study was carried out to investigate the twinning rate and its correlates from January 1991 to December 2005 in 10 villages of the Rural Health Centre, Pohir, a field practice area of the Department of Community Medicine, Dayanand Medical College and Hospital, Ludhiana, Punjab, India. During this study period, 5070 deliveries took place. A total of 5017 singleton births and 53 sets of twins were recorded, giving a twinning rate of 10.45 per 1000 total deliveries. Monozygotic and dizygotic twinning rates were estimated as 2.96 and 7.49 per 1000 deliveries, respectively. The twinning rate was strongly associated with maternal age; the twinning rate for mothers between 30 and 34 years of age was about 10 times higher than the rate for mothers younger than 20 years. This variation was due to variation in dizygotic twinning; the rate of monozygotic twinning was almost constant for all ages. The twinning rate was highest at gestational order 4 or higher. The perinatal mortality rate among the twins was 173.1 per 1000 total twin births and was significantly higher among the group in which diagnosis of twins was not done during the prenatal period. We should expect 1 twin birth per 100 births, and because perinatal mortality is alarmingly high in undiagnosed twin pregnancies, early recognition of twin pregnancy during prenatal visits and delivering in a health facility with adequately trained personnel should be encouraged.