Human assisted conception: a cautionary tale. Lessons from domestic animals.

Area of Science:

• Reproductive Biology
• Developmental Biology
• Animal Science

Background:

• Assisted reproductive technologies (ARTs) like embryo culture and nuclear transfer are widely used in farm animal reproduction.
• These technologies can result in large offspring syndrome (LOS), characterized by oversized fetuses and newborns, sometimes with abnormalities.
• The biological differences between in vivo- and in vitro-produced embryos are crucial for understanding these phenomena.

Purpose of the Study:

• To explore the associations between ARTs and large offspring syndrome.
• To investigate the biological differences between in vivo- and in vitro-produced embryos.
• To propose a research framework for understanding anomalies in early embryo development.

Main Methods:

• Review of existing literature on embryo-based technologies and their outcomes.
• Comparative analysis of in vivo- and in vitro-produced embryos.
• Framework proposal based on cellular stress responses in early development.

Main Results:

• ARTs, including embryo culture and nuclear transfer, are linked to large offspring syndrome and potential fetal/newborn abnormalities.
• Significant biological differences exist between embryos developed in vivo and in vitro.
• Cellular stress is proposed as a unifying factor explaining anomalies in early embryo development.

Conclusions:

• ARTs require careful consideration due to risks of large offspring syndrome and developmental abnormalities.
• Further research into the molecular, biochemical, and physiological basis of early mammalian development is essential.
• Development of assisted conception technologies should prioritize scientific understanding over commercial drivers to ensure animal welfare.