Being pregnant with more than 1 baby is exciting and is often a happy event for many
couples. However, multiple pregnancy has increased risks for complications. The most
common complications include the following:
Preterm labor and birth. Over 60% of twins and nearly all higher-order multiples are premature (born before
37 weeks). The higher the number of fetuses in the pregnancy, the greater the risk
for early birth. Premature babies are born before their bodies and organ systems have
completely matured. These babies are often small, with low birthweights (less than
2,500 grams or 5.5 pounds), and they may need help breathing, eating, fighting infection,
and staying warm. Very premature babies, those born before 28 weeks, are especially
vulnerable. Many of their organs may not be ready for life outside the mother's uterus
and may be too immature to function well. Many multiple birth babies will need care
in a neonatal intensive care unit (NICU).
Gestational hypertension. Women with multiple fetuses are more than twice as likely to develop high blood pressure
of pregnancy. This condition often develops earlier and is more severe than pregnancy
with one baby. It can also increase the chance of placental abruption (early detachment
of the placenta).
Anemia. Anemia is more than twice as common in multiple pregnancies as in a single birth.
Birth defects. Multiple birth babies have about twice the risk of congenital (present at birth) abnormalities
including neural tube defects (like spina bifida), gastrointestinal, and heart abnormalities.
Miscarriage. A phenomenon called the vanishing twin syndrome in which more than 1 fetus is diagnosed,
but vanishes (or is miscarried), usually in the first trimester, is more likely in
multiple pregnancies. This may or may not be accompanied by bleeding. The risk of
pregnancy loss is increased in later trimesters as well.
Twin-to-twin transfusion syndrome. Twin-to-twin transfusion syndrome (TTTS) is a condition of the placenta that develops
only with identical twins that share a placenta. Blood vessels connect within the
placenta and divert blood from one fetus to the other. It happens in about 15% of
twins with a shared placenta.
In TTTS, blood is shunted from 1 fetus to the other through blood vessel connections
in a shared placenta. Over time, the recipient fetus receives too much blood. This
can overload the cardiovascular system and cause too much amniotic fluid to develop.
The smaller donor fetus does not get enough blood and has low amounts of amniotic
fluid. TTTS can be treated during pregnancy by withdrawing some of the extra fluid
with a needle or with surgery on the placenta. Sometimes, the twins may need to be