In order to evaluate the impact of assisted reproductive technology (ART) procedure and individual factors on the sex ratio of singletons and twins at birth after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) treatment in China. We conducted a retrospective cohort study including patients undergoing their frst cycle of IVF or ICSI with autologous oocytes from 2001 to 2015. A total of 7410 babies were born from 5832 women with 7410 live birth. The secondary sex ratio (SSR) in singletons was signifcantly higher than twins (53.97% vs. 50.89%, P=0.009). The largest disparity was observed in ‘thawed blastocyst embryos ICSI’ subgroup that SSR was 59.84% in singletons and 42.45% in twins (P=0.013). Blastocyst transfer was positively associated with elevated SSR when compared to cleavage stage embryos in singletons (Odds Ratio [OR]=1.17, P<0.001). In addition, paternal age was signifcantly associated with SSR (OR=0.75, P=0.014). While the decrease of SSR was signifcantly associated with ICSI when compared to IVF (OR=0.61, P=0.046) in twins. Blastocyst transfer increases SSR in comparing with cleavage stage embryos in singletons, while the use of ICSI reduces SSR in twins. Our fndings ofered important complement for better understanding the underlying determinant of SSR in ART ofspring.
https://www.nature.com/articles/s41598-017-06152-9
