Full text in pdf format

Seasonal variation in twin birth rates in Brazil

B. Beiguelrnan; H.O. Villarroel-Herrera

Departamento de Genética Médica, Faculdade de Ciéncias Médicas, UNICAMP, Caixa Postal 6111, 13081 Campinas, SP, Brasil

ABSTRACT

A significantly higher incidence of monozygotic twins was observed in both summer and winter among 31,732 deliveries at a maternity hospital in Campinas, State of São Paulo, Brazil (Maternidade de Campinas). No evidence of seasonality was detected for dizygotic twins. This hospital serves about 70% of the parturients of all social classes of this city, which now has more than one million inhabitants and may be considered as representative of the southeastern Brazilian population.

Keywords: Seasonal variation in twin birth rates in Brazil.

REFERENCES

Benirschke, K. (1981). The pathophysiology of the twinning process. In: Principles and Practice of Obstetrics and Perinatology (Iffy, L. and Kaminetzky, H.A., eds.). John Wiley and Sons, Inc., Ch. 67: 1165-1170.

Bonnelykke, B., Sogaard, J. and Nielsen, J. (1987). Seasonality in twin birth rates, Denmark, 1936-84. J. Epidemiol Community 41: 338-343.

Czeizel, A. (1974). Unexplainable demographic phenomena of multiple births in Hungary. Acta Genet. Med Gemellol 22 (Suppl.): 214-218.

Doherty, J.D.H. and Lancaster, P.A.L. (1986). The secular trend of twinning in Australia, 1853-1982. Acta Genet. Med. Gemellol 35: 61-76.

Edwards, J. (1938). Season and rate of conception. Nature 142: 357.

Elwood, J.M. (1978). Maternal and environmental factors affecting twin births in Canadian cities. Br. J. Obstet. Gynecol 85: 351-358.

Erhard, C.L., Nelson, F.O. and Palter, J. (1971). Seasonal patterns of conception in New York City. Am. J. Publ Health 61: 2246-2258.

James, W.H. (1976). Seasonality in twin births. Ann. Hum. Biol 3: 193-195.

James, W.H. (1980). Seasonality in twin and triplet births. Ann. Hum. BioL 7: 163-175.

Kamimura, K. (1976). Epidemiology of twin births from a climatic point of view. Br. J. Pre^y. Soc. Med 30: 175-179.

Picard, R., Fraser, D., Hagay, Z.J. and Leiberman, J.R. (1989). Twinning in southern Israel; secular trends, ethnic variation and effects of maternal age and parity. Europ. J. Obstet. GynecoL Reprod. Biol. 33: 131-139.

Selvin, S. and Janerich, D.T. (1972). Seasonal variation in twin births. Nature 237: 289-290.

Timonen, S. and Carper, E. (1968). Multiple pregnancies and photoperiodicity. Ann. Chir. Gynaecol Fenn. 57: 135-138.

Zahalkova, M. (1974). Multiple births in Southern Moravia. Acta Genet. Med. GemelloL 22 (Suppl.): 210-213.