In this section:
The fertilised egg divides into two identical cells – then four, then eight, then 16, and then many billions, and 266 days later – your baby.
Conception normally occurs when a single sperm penetrates an ovum, forming a single cell. From that moment you are pregnant and... a life begins.
Almost immediately after conception, the ovum travels along the fallopian tube and embeds itself in the uterine lining.
The inherited characteristics of your baby are determined at conception. The complement of 46 chromosomes, 23 from each parent, determine your baby’s hair colour, blood type, approximate height, body shape and many other characteristics.
Twins occur in one in 90 pregnancies.
- Fraternal twins result from two eggs being fertilised by two sperm.
- Identical twins result from one sperm fertilising one egg and splitting into two separate embryos, often sharing one placenta.