A–Z Glossary

Chorionicity

Chorionicity describes whether multiples share a placenta or amniotic sac, which affects monitoring and birth timing.

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Identical vs fraternal twins differences

Identical vs fraternal twins differences

The basic biology behind twin types Twin pregnancy begins in one of two broad ways. In a monozygotic pregnancy, a single egg is fertilized by a single sperm, creating one zygote. That early embryo then splits into two separate embryonic lines, which develop into identical twins. In a dizygotic pregnancy, two eggs are released in […]

Labor timeline for twins and multiple pregnancy

Labor timeline for twins and multiple pregnancy

Why the timeline is different In a multiple pregnancy, the labor timeline starts well before the first regular contraction. Obstetric teams usually build a delivery plan around gestational age, chorionicity, fetal presentations, growth, amniotic fluid, placental function, maternal health, and the availability of neonatal care. This is why two people pregnant with twins may receive […]