Blastocyst transfer and gender: IVF versus ICSI

Area of Science:

• Reproductive Medicine
• Embryology
• Human Genetics

Background:

• The sex ratio at birth in the general population is approximately 0.515 males.
• Assisted reproductive technologies (ART) may influence the sex ratio of neonates.
• Understanding sex ratio variations in ART is crucial for reproductive counseling.

Purpose of the Study:

• To compare the sex ratio of neonates born after day 5 embryo transfer via fresh in vitro fertilization (IVF), fresh intracytoplasmic sperm injection (ICSI), and frozen embryo replacement (FER) with the expected sex ratio.
• To investigate potential differences in sex ratio among different ART methods.

Main Methods:

• Retrospective analysis of data from 1995-2007 for IVF, ICSI, and FER.
• Inclusion of relevant data from existing literature on sex ratios after prolonged embryo culture.
• Statistical comparison of observed sex ratios against expected ratios.

Main Results:

• A total of 420 births after day 5 transfer showed 225 males and 195 females.
• Analysis of combined literature data revealed a male birth ratio of 0.545, significantly different (p=0.004) from the expected 0.515.
• Subgroup analysis indicated a higher proportion of females after ICSI (30 female, 21 male) and FER in the center's data.

Conclusions:

• Significantly more male births than expected are observed after day 5 embryo transfer in IVF.
• Preliminary findings suggest a potential shift towards more female births after ICSI and FER.
• Further research is warranted to elucidate the factors influencing sex ratios in specific ART procedures.