Maternal smoking during pregnancy increases the risk of gut microbiome-associated childhood overweight and obesity.

"Competing interests Francis Ka-Leung Chan is Board Member of CUHK Medical Centre. He is a co-founder, non-executive Board Chairman and shareholder of GenieBiome Ltd. He receives patent royalties through his affiliated institutions. He has received fees as an advisor and honoraria as a speaker for Eisai Co. Ltd., AstraZeneca, Pfizer Inc., Takeda Pharmaceutical Co., and Takeda (China) Holdings Co. Ltd. Siew Chien Ng has served as an advisory board member for Pfizer, Ferring, Janssen, and Abbvie and received honoraria as a speaker for Ferring, Tillotts, Menarini, Janssen, Abbvie, and Takeda. Siew Chien Ng has received research grants through her affiliated institutions from Olympus, Ferring, and Abbvie. Siew Chien Ng is a founder member, non-executive director, non-executive scientific advisor, and shareholder of GenieBiome Ltd. Siew Chien Ng receives patent royalties through her affiliated institutions. Francis Ka-Leung Chan, Siew Chien Ng, and Hein Min Tun are named inventors of patent applications held by the CUHK and MagIC that cover the therapeutic and diagnostic use of microbiome. All other coauthors have no conflict of interest."