Pattern of birth in early-onset anorexia nervosa: an equatorial study.

The International journal of eating disorders

PubMedID: 15690468

Willoughby K, Bowen R, Lee EL, Pathy P, Lask B. Pattern of birth in early-onset anorexia nervosa: an equatorial study. Int J Eat Disord. 2005;37(1):61-4.
OBJECTIVE
Patients with anorexia nervosa (AN) born in the northern and southern hemispheres are more likely to be born during spring months than at any other time of the year. It has been hypothesized that environmental temperature at the time of conception may have a significant role in this pattern of findings. The current study aims to investigate the pattern of birth of early-onset AN patients in an equatorial region (Singapore), where there is little difference in environmental temperature throughout the year.

METHOD
Dates of birth were collected for 102 patients who were born in Singapore and diagnosed with early-onset AN. The patterns of birth were analyzed using chi-square analysis.

RESULTS
There was no difference across the year in the birth patterns of patients with early-onset AN in Singapore, nor were there any differences between patients with restrictive and binge/purge AN.

DISCUSSION
This lack of seasonal variation in the equator adds support to the "temperature at conception" hypothesis.