Surrounding greenness and pregnancy outcomes in four Spanish birth cohorts

Surrounding greenness is associated with increased birth weight and head circumferenceThis study examined the association of greenness around mothers’ homes at the time of birth with outcomes of 2,393 births between 2003-2008 in four cohorts within two distinct regions of the Iberian Peninsula of Spain with different climate and vegetation patterns. The purpose of the study was to evaluate associations between surrounding greenness in the environment where the mother was in residence and the child's birth weight, head circumference and gestational age at delivery.

The study found a positive association between surrounding greenness and birth weight as well as head circumference. However, there was no association with gestational age.  The difference in head circumference was quite small (1-2mm) and may be inconsequential for an individual child, though could be important at the population level. The effects of greenness on birth weight and head circumference were significant for all distances from the mother’s home (though stronger for the greater distances) and for both regions of the country.  The association were strongest for mothers with lower educational levels. The association remained after controlling for mothers’ nitrogen dioxide levels during pregnancy, though the association of greenness and birth weight was slightly diminished after controlling for this air pollution measure. Self-reported measures of physical activity were not related to greenness prior to pregnancy but were for late pregnancy suggesting that greenness may facilitate physical activity during pregnancy.

The authors concluded that surrounding greenness may be more important for fetal growth than for length of pregnancy and may have the most impact on mothers of lower educational and socio-economic levels.

At the time of publication this was one of just a few studies on the topic of greenness and birth outcomes, and the only to examine head circumference, which may be a predictor of eventual brain size and intelligence. The results of this study are consistent with other studies on this topic at the time of publication.