The Science of Baby Making

What It Covers

Embryologists Joyce Harper and Ben Steventon explain human embryo development from fertilization through gastrulation, discussing IVF technology, genetic testing, frozen embryos, age-related fertility challenges, and emerging technologies like artificial wombs and designer babies.

Key Questions Answered

• •Embryo Biopsy Safety: Scientists can remove two cells from an eight-cell embryo for genetic testing without affecting development, as cells remain totipotent at this stage and can differentiate into any tissue type needed for normal growth.
• •Female Fertility Decline: Women are born with approximately two million eggs, declining to 300,000-400,000 by puberty. Chromosomes in aging eggs become increasingly confused during meiosis, causing higher miscarriage rates and chromosomal abnormalities like Down syndrome as women age.
• •Frozen Embryo Viability: Embryos can be frozen at the blastocyst stage in suspended animation and successfully thawed months or years later for implantation. Four viable cells from an eight-cell embryo are sufficient to develop into a complete baby.
• •Future Reproductive Technology: Scientists are close to creating eggs and sperm from stem cells derived from skin tissue, potentially eliminating age-related infertility entirely. Combined with artificial wombs, this technology could enable reproduction at any age within twenty years.