Winter babies learn to crawl earlier

Babies born in the winter months learn to crawl earlier than those born in the summer, a new study has found.
The season of a baby's birth influences its motor development during its first year of life, the study by University of Haifa in Israel has found.
Babies born in the winter (between December and May) start crawling earlier compared to babies born in the summer (June-November), researchers found.
Forty-seven healthy babies with typical development patterns were divided into two groups.
The first group comprised "summer-fall" babies, 16 babies born from June to November, and the second, "winter-spring" babies, 31 babies born from December to May.

The study consisted of motor observations in the babies' homes when there were seven months old, and a follow-up session when they began to crawl.

Parents were asked to record the stages in their babies' development before and between the observations.
The study used the Alberta Infant Motor Scale (AIMS) to track the babies' development. The scale relates to four positions: Prone (on the stomach), supine (on the back), sitting, and standing.
The average age at which the babies started crawling was 31 weeks.
While the babies born in the winter (who started to crawl in the summer) started to crawl at an average 30 weeks, those born in the summer (who started to crawl in the winter) began crawling at an average of 35 weeks, with no differences noted between the boys or the girls or in the initial style of crawling (belly crawling or using hands and knees).

The overall AIMS score was higher for those babies born in the winter, and the score for movement in the prone position, the scale most meaningful in connection with crawling was, significantly higher for the babies in the winter group.
By contrast, there was no significant difference in the scores for the supine position, sitting, or standing between the two groups.
"The difference in crawling onset of four weeks constitutes 14 per cent of a seven-month-old's life and is significant," researchers said.
"The geographic location and the local climate where the study is conducted is important to understand the findings," they added.

A seasonal effect is found in places where the differences in the home environment between summer and winter are significant, researchers said.
Studies done in Denver, Colorado and in Osaka, Japan found a seasonal effect that corresponds with the findings of the Haifa study, but a study conducted in Alberta, Canada, where winters are long and cold on the one hand, but the home environment (because of winter heating) is very similar all year round, the seasonal effect was not observed.