• Supporting Scientific Evidence
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Studies have indicated that children who born during certain times of the year (winter and early spring) have a higher than normal incidence of schizophrenia.

Relative Risk for Schizophrenia depending upon Month of Birth

According to an article in the New Scientist magazine, research suggests people who develop schizophrenia in Europe and North America are more likely to be born in the winter and early spring (February and March in the Northern Hemisphere) In other words, the subjects who were born during these months had a slightly higher than average rate of schizophrenia, while subjects born in August and September had a slightly lower than average rate. There seems to be about a 10% difference in risk of schizophrenia between the high (Winter and Spring) and low risk months of birth.

One possible reason that researchers believe may explain this seasonality of schizophrenia risk is the association between winter/spring births and schizophrenia may be related to sunlight exposure. A lack of sunlight (for example, during the shorter days of winter) can lead to vitamin D deficiency, which scientists believe could alter the development of a child's brain in the mother's womb and after birth.

Action: For reduced risk of schizophrenia, a mother may want to make sure that she gets at least double the recommended dose of vitamin D on a regular basis before and during pregnancy. In a recent study on vitamin D deficiency in mothers during pregnancy, Dr. Lisa Badner stated "While many prenatal vitamins contain about 400 international units (iu) of vitamin D, taking perhaps 1,000 units might be preferable". Vitamin D can be bought as an over-the-counter nutritional supplement, or it may be included in store-bought milk and orange juice (check the carton).

A couple planning children may also want to try and schedule the birth for a time outside the "winter and spring" time frame (both of which have been implicated as times when higher than average number of people are born that later develop schizophrenia). Research suggests that the birth months that have the lowest risk of schizophrenia are July through October.

Supporting Research (a sample):

• Vitamin D deficiency widespread during pregnancy, Increasing Schizophrenia Risk in Children
• Schizophrenia linked to mother's lack of sunlight - New Scientist Magazine
• The chance of developing schizophrenia may be directly linked to how sunny it was in the months before a person's birth, research suggests. (News)
• Schizophrenia and the Seasons (News)
• Low maternal vitamin D as a risk factor for schizophrenia: a pilot study using banked sera. (Research)
• Exposure to sunlight, vitamin D and schizophrenia (Research)
• Seasonality of symptom onset in first-episode schizophrenia (Research)
• Season of birth in Japanese patients with schizophrenia. (Research)
• Long-term trends in sunshine duration and its association with schizophrenia birth rates and age at first registration--data from Australia and the Netherlands (Research)
• Risk factors in schizophrenia. Season of birth, gender, and familial risk (Research)