How quickly your baby develops depends on the season of the year and thus possibly vitamin D levels. Researchers at the Hamamatsu University School of Medicine recently studied the seasonality of development of 926 infants born between December 2007 and September 2010.
Tsuchiya KJ, et al and the H. B. C. Study Team. Seasonal Variations of Neuromotor Development by 14 Months of Age: Hamamatsu Birth Cohort for Mothers and Children (HBC Study). PLoS One. 2012;7(12):e52057
First, they pointed out that:
- In the northern hemisphere, birth rates are usually high in the spring months, which has been thought to be related to higher conception rates in the summer and early autumn months.
- Studies have found that birth weight tends to be higher in the colder months, consistent with the theory that infants born near the equator under natural conditions will be smaller than winter born babies will be. It has always made sense to me that in the natural state, large babies would be selected against.
- Another study reported that the growth in height of infants speeds up during the summer months, irrespective of month of birth.
- Children born in winter and spring months are at higher risk of later diagnosis with schizophrenia.
- Children born in March are at a higher risk of autism.
In this study of 926 infants, the authors found that the infants born in summer and autumn achieved the highest performance in neuromotor skills. In contrast, those born in winter and spring showed the lowest development. They concluded,
“In this study, infants who showed the most advanced gross motor skills at 6 months of age . . . experienced the warmest months by the age of 6 months, while those born in September and October showed the least advanced gross motor development and had experienced the coldest 6 months after birth.”
Another good reason to be sure baby has enough vitamin D, or better yet enough sunshine as the US government used to recommend.