Multiple Births

Identical Twins

• Monozygotic

• Formed from 1 sperm and 1 egg

• The zygote splits into 2

• Always the same gender

Fraternal Twins

• Dizygotic twins

• Formed from two sperm and two eggs

• Could be 2 boys or 2 girls or one of each

Twin Statistics

•3% of births are twin births

• 23/1,000 Fraternal Twin

• 4/1,000 Identical Twins

Conjoined Twins• Identical twins who did

not completely separate during the zygote stage

• Surgery to separate conjoined twins depends on the extent of sharing vital organs

• Occurs in about 1 in 50,000 human pregnancies

Conjoined Twins: Abigail and Brittany Hensel

Born conjoined in 1990Today, they are 24 years old and school teachers

Triplets (3)

• Formed the same way as twins

• Can be identical or fraternal

Quadruplets (4)

Quintuplets (5)

Sextuplets (6)

Septuplets (7)

Octuplets (8)

Chukwu Octuplets (8 born, 1 death)Born in 1998 in Houston, Texas

Suleman OctupletsBorn in 2009 in

Bellflower, California