The authors declare they have no competing interests.
MJ and CL developed the first manuscript draft. YZ, JQ, QL and SW contributed to the study design and oversaw the field implementation. YZ, MZ, XH, and HC developed the initial protocol. LL, XL, CZ, HZ, RX, DZ, YD, XH, HZ, HB, YC, ZT, RL, TY, JS, XX, XL, WW, YW, BM, and WQ contributed to the development of the study design and monitoring. CZ and XL developed the statistical analyses. MJ, HH and NZ conducted the data analyses. All authors reviewed and approved the manuscript.
Early studies have suggested that biomass cooking fuels were associated with increased risk of low birth weight (LBW). However it is unclear if this reduced birth weight was due to prematurity or intrauterine growth restriction (IUGR).
In order to understand the relationship between various cooking fuels and risk of LBW and small for gestational age (SGA), we analyzed data from a birth cohort study conducted in Lanzhou, China which included 9,895 singleton live births.
Compared to mothers using gas as cooking fuel, significant reductions in birth weight were observed for mothers using coal (weight difference = 73.31 g, 95 % CI: 26.86, 119.77) and biomass (weight difference = 87.84 g, 95 % CI: 10.76, 164.46). Using biomass as cooking fuel was associated with more than two-fold increased risk of LBW (OR = 2.51, 95 % CI: 1.26, 5.01), and the risk was mainly seen among preterm births (OR = 3.43, 95 % CI: 1.21, 9.74). No significant associations with LBW were observed among mothers using coal or electromagnetic stoves for cooking.
These findings suggest that exposure to biomass during pregnancy is associated with risk of LBW, and the effect of biomass on LBW may be primarily due to prematurity rather than IUGR.