From: Association of prenatal and childhood environment smoking exposure with puberty timing: a systematic review and meta-analysis
Puberty index
RR
95% CI
p
Number of boys with early voice break
1.34
1.29, 1.40
0.00
Number of boys with early growth of penis
0.99
0.94, 1.04
0.64
Number of boys with early pubic hair development
0.93, 1.04
0.60