Table 1.

Summary of results of included studies on greenness and maternal health and pregnancy outcomes

Reference, year	Population	Study design	Exposure	Outcome	Main finding	Mediation or effect modification
Agay-Shay et al11, 2014	39,132 singleton live births from a registry birth cohort in Tel Aviv, Israel, 2000–2006	Cross-sectional	– Average NDVI in 100, 250, and 500 m buffers around maternal residence – Residence within a buffer of 300 m from boundaries of major (>5,000 m2) green space	– BW – LBW – VLBW – Gestational age – Preterm deliveries – Very preterm deliveries	– Interquartile range increase in greenness associated with 19.2 g increase in BW (95% CI 13.3, 25.1) and 16% decreased odds of LBW (95% CI 0.78, 0.90) – No associations for gestational age, preterm, very preterm	Statistically significantly stronger associations among those of lower SES
Casey et al7, 2016	12,821 infants born to 10,787 mothers at a single Pennsylvania hospital, United States, 2006–2013	Birth cohort	Seasonal average NDVI in 250 and 1,250 m radii around maternal residence assigned based on seasons of gestation	– Term BW – SGA – Preterm birth – Apgar score	In cities, but not boroughs or townships, higher greenness (tertiles 2–3 vs 1) was associated with both preterm (OR 0.78, 95% CI 0.61, 0.99) and SGA birth (OR 0.73, 95% CI 0.58, 0.97), but not BW or Apgar score	No evidence of effect modification by family SES or community deprivation
Dadvand et al12, 2012 (Green space, health inequality and pregnancy)	8,246 births, Spain, 2001–2005	Birth cohort	– NDVI in 100 m buffer around maternal residence – Major green space in 500 m buffer of address	– BW – Gestational age at delivery	None of the indicators of green exposure were associated with BW or gestational age	Associations observed among mothers with the lowest education level
Dadvand et al13, 2012 (Surrounding greenness and pregnancy outcomes in 4 Spanish cohorts)	2,393 singleton live births, Spain, 2003–2008	Birth cohort	NDVI in 100, 250, and 500 m around maternal residence	– BW – Gestational age – Head circumference	An interquartile range increase in NDVI within a 500 m buffer associated with increases in BW (44.2 g, 95% CI 20.2, 68.2) and head circumference (1.7 mm, 95% CI 0.5, 2.9) but not gestational age	– Association between BW and greenness among infants of mothers with low and moderate education – Head circumference association was strongest in mothers with moderate education
Dadvand et al14, 2014	10,780 singleton live births, United Kingdom, 2007–2010	Birth cohort	– NDVI in 50, 100, 250, 500, and 1,000 m around maternal residence – Residential proximity to green spaces living within 300 m of a green space with an area of $5,000 m2	BW	Positive association between BW and residential surrounding greenness; for example, an interquartile range increase in NDVI in 250 m buffer associated with 16.2 g (95% CI 1.7, 30.8) increase in BW	– Positive association between BW and residential surrounding greenness for white but not Pakistani participants – Surrounding greenness: stronger associations for those with lower education and lower SES neighborhood, in larger but not smaller buffers
Donovan et al15, 2011	5,696 singleton live births in Portland, Oregon, United States, 2006–2007	Cross-sectional	Percentage tree canopy in the 50, 100, and 200 m buffers around maternal residence	– SGA – Preterm	10% higher tree canopy cover associated with 1% lower odds of SGA – No association with preterm
Ebisu et al16, 2016	239,811 babies born in Connecticut, United States, 2000–2006	Cross-sectional	Green space and fraction thereof (ie, forest, shrub, herbaceous, and cultivated land) within 250 m from residence based on data from the National Land Cover Database	– BW – LBW – SGA	– An interquartile range increase in fraction of green space within 250 m of residence associated with 3.2 g (95% CI 0.4, 6.0) higher BW – An interquartile range increase in green space associated with 7.6% (95% CI 2.6, 12.4) decreased risk of LBW	– No effect modification by race/ethnicity and SES for any outcomes – With less educational attainment, beneficial effect of green space for BW and LBW was stronger, but not statistically significant
Grazuleviciene et al17, 2015	3,292 singleton live births, Kaunas, Lithuania, 2007–2009	Birth cohort	– NDVI within straight line buffers of 100, 300, and 500 m – Distance to nearest city park (<300, 300–1,000, and >1,000 m)	– BW – TLBW – LBW – SGA – Preterm – Gestation length	– No statistically significant associations between NDVI and BW, LBW, TLBW, SGA, preterm, gestation length – No statistically significant associations among distance to park metrics	For subjects with low surrounding greenness and high distance to park, increased risks for LBW (OR 2.23, 95% CI 1.20, 4.15), TLBW (OR 2.97, 95% CI 1.04, 8.45), and preterm birth (OR 1.77, 95% CI 1.10, 2.81)
Hystad et al18, 2014	64,705 singleton births, Canada, 1999–2002	Birth cohort	NDVI within 100 m of participants’ homes	– BW – SGA – Very preterm – Moderately preterm	An interquartile range increase in NDVI (0.1) associated with higher term BW (20.6 g, 95% CI 16.5, 24.7) and decreases in the likelihood of SGA, very preterm (<30 weeks), and moderately preterm (30–36 weeks) birth	Associations robust to adjustment for air pollution and noise exposures, neighborhood walkability, and park proximity
Laurent et al8, 2013	81,186 infants in Los Angeles and Orange counties, California, United States, 1997–2006	Birth cohort	NDVI within radial buffers of 50, 100, and 150 m around participants’ home addresses	– BW – Preterm	– An interquartile range increase in NDVI associated with BW increase of 6.09 g (95% CI 3.11, 9.06) within 50 m buffer – An interquartile range increase in NDVI associated with reduced risk of preterm (OR 0.985, 95% CI 0.972, 0.997) within 150 m buffer – No significant association with preeclampsia	Statistically significant associations between greenness and BW persisted in the 50 m buffer after adjustment for air pollutants, but not in the 100 m buffer
Kihal-Talantikite et al19, 2013	Infant deaths, Lyon, France, 2000–2009	Ecological	Proportion of census block total area comprised of natural area (ie, parks, forests)	Infant mortality	– Spatial distribution of infant mortality high risk cluster in the south east of the Lyon metropolitan area (P<0.003) – Cluster disappeared (P=0.12) after adjustment for greenness level and socioeconomic deprivation – Both factors had independent effect	No evidence of statistically significant interaction between greenness and SES
Markevych et al20, 2014	3,203 infants in Munich and Wesel, Germany, 1996–1999	Birth cohort	– NDVI within radial buffer of 100, 200, 500, and 800 m around maternal residence – Area of green space within 500 m buffer around residence	BW	– An interquartile range increase in NDVI associated with BW increase of 17.6 g (95% CI 0.5, 34.6) for 500 m buffer – Similar trend for other buffer sizes	– Results remained robust when additionally adjusted for noise or maternal stress during pregnancy – Stronger associations for mothers with <10 years of education
McEachan et al9, 2016	12,453 mothers and 13,818 infants in Bradford, England, 2007–2011	Birth cohort	NDVI within straight line buffer of 100, 300, and 500 m around maternal residence	Peripartum depression	– Pregnant women in the greener quintiles were statistically significantly less likely (18%–23%) to report depressive symptoms than those in the least green quintile (for 100 m buffer) – Similar trend but not statistically significant within 300, 500 m buffers	– Association stronger in mothers with less education – No statistically significant effect modification by area deprivation – Physical activity was a small, but statistically significant, partial mediator (7.8%)
Young et al10, 2016	9,692 cases of gestational diabetes and 6,288 cases of preeclampsia among births to women in Los Angeles and Orange counties, California, United States, 2007–2008	Ecological	Green space area in zip code	– Gestational diabetes – Preeclampsia	– No association between green space and gestational diabetes – For each km2 increase in ZIP code green space, prevalence ratio for preeclampsia (per 100,000 individuals) was 0.82 (P=0.077)

Abbreviations: NDVI, Normalized Difference Vegetation Index; CI, confidence interval; OR, odds ratio; SES, socioeconomic status; LBW, low birth weight; BW, birth weight; TLBW, term low birth weight; SGA, small for gestational age; VLBW, very low birth weight.