Abstract
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 intra-cytoplasmic sperm injection (ICSI) treatment in China. We conducted a retrospective cohort study including patients undergoing their first 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 significantly 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 significantly associated with SSR (OR = 0.75, P = 0.014). While the decrease of SSR was significantly 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 findings offered important complement for better understanding the underlying determinant of SSR in ART offspring.
Highlights
Primary sex ratio (PSR) means the sex ratio at conception and is always calculated as male proportion
We conducted a retrospective study to explore the factors associated with secondary sex ratio (SSR) in singletons and twins born to in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI)
We found that blastocyst transfer can increase SSR both singletons and twins, and our findings firstly indicated that use of ICSI increased birth of twin girls
Summary
Primary sex ratio (PSR) means the sex ratio at conception and is always calculated as male proportion. It is 1.7 times higher than female under completely natural circumstances in humans[1]. What’s more, social factors for male sex preference and sex selection in certain countries rise the SSR in natural conception[9]. As women undergoing ART received Ovulation induction treatment and the embryos cultured in vitro for some time, the key to sex ratio in IVF and/or ICSI babies were not completely similar with natural conception. What’s more, there’s no study discuss the SSR of ART offspring between singletons and twins. We conducted a retrospective cohort study including 7410 ART offspring to comprehensively investigate the potential determinants of SSR among both the singletons and twins
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