Seasonal migration and seasonal variation in fecundability: Effects on birth rates and birth intervals

Epidemiological effects of seasonal oscillations in birth rates.

Seasonal oscillations in birth rates are ubiquitous in human populations. These oscillations might play an important role in infectious disease dynamics because they induce seasonal variation in the number of susceptible individuals that enter populations. We incorporate seasonality of birth rate into the standard, deterministic susceptible-infectious-recovered (SIR) and susceptible-exposed-inf...

The effect of seasonal host birth rates on disease persistence.

In this paper, we add seasonality to the birth rate of an SIR model with density dependence in the death rate. We find that disease persistence can be explained by considering the average value of the seasonal term. If the basic reproductive ratio R(0)>1 with this average value then the disease will persist and if R(0)<1 with this average value then the disease will die out. However, if the und...

Seasonal variation in suicide-rates.

Birth weights of South African babies. III. Seasonal variation in birth weight.

Reports on seasonal variation in birth weight are conflicting and inconclusive. No variation was observed by Brenton (1922) or by Bakwin and Bakwin (1929); babies born in the summer were said by Murray (1924), Abels (1926), Toverud (1933), Bivings (1934), Li (1936), and Donald (1939) to be heavier than those born in the winter; Adersen (1899) reported that babies born in the winter were heavier...

Seasonality of birth in seasonal affective disorder.

BACKGROUND Season of birth or seasonal changes in putative etiologic factors are thought to influence the development of several psychiatric illnesses. The aim of this investigation was to examine seasonal differences in the frequency of birth in a clinical sample of patients with seasonal affective disorder (SAD). METHOD 553 outpatients suffering from SAD-DSM-IV-defined depressive disorder w...