Seasonality in twin birth rates, Denmark, 1936-84.
- 1 December 1987
- journal article
- research article
- Published by BMJ in Journal of Epidemiology and Community Health
- Vol. 41 (4) , 338-343
- https://doi.org/10.1136/jech.41.4.338
Abstract
A study was made of seasonality in twin birth rate in Denmark between 1977 and 1984. We studied all twin births (n = 45,550) in all deliveries (N = 3,679,932) during that period. Statistical analysis using a simple harmonic sinusoidal model provided no evidence for seasonality. However, sequential polynomial analysis disclosed a significant fit to a fifth order polymomial curve with peaks in twin birth rates in May-June and December, along with troughs in February and September. A falling trend in twinning rate broke off in Denmark around 1970, and from 1970 to 1984 an increasing trend was found. The results are discussed in terms of possible environmental influences on twinning.This publication has 38 references indexed in Scilit:
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