Emma Hawe, Alison Macfarlane and John Bithell: Daily and seasonal variation in live births, stillbirths and infant mortality in England and Wales, 1979–96. In: Health Statistics Quarterly. 9 Spring 2001 (PDF; 180 kB), S. 7: „There was a clear seasonal pattern in the number of daily live births throughout the entire period, with lower numbers of births in the winter than the summer months.“
