Effects of Sibship Size and Birth Order on Sexual and Reproductive Health among Sexually Active Young People in China.

Only children are more prevalent among young people today in China due to the globally renowned one-child policy since the 1980s, but the association between sibship size and the sexual activity of youth needs to be further clarified. The aim of this study was to explore the effect of siblings, being an only child, and birth order on the sexual and reproductive health (SRH) of young people. Data were utilized from 11,044 sexually active college/university students who participated in a large-scale national survey. Overall, numerous undergraduates nationally identified as only children (43.5%); for non-only children, 32.4% were oldest children, 10.5% were middle children, and 13.6% were youngest children. For both sexes, having more siblings was related to having risky sexual debuts and less contraceptive use. Furthermore, young men and young people born in rural areas with more siblings were more likely to have severe health outcomes, such as unwanted pregnancy and sexually transmitted infection(s). Finally, being an only child protected youth from risky sexual behaviors and adverse health outcomes. For students with siblings, middle children were more inclined to risky sexual initiation and low frequency of contraception compared to first-borns. Our analysis provides the first evidence of one child and sibling effects on SRH in China and has significant implications for promoting SRH in the context of encouraging childbirth.