Twin Pregnancy Preterm Labor
Preterm Delivery (before 37 w)
is the most common complication of a twin pregnancy. The average twin pregnancy
delivers at about 35 weeks Women who have
had a previous preterm single baby appear to be at higher risk for preterm
delivery than other women with a twin pregnancy [1,2]. In addition, twin
pregnancies conceived by assisted reproductive technology (in vitro) may also be at
increased risk for preterm delivery compared to women with naturally conceived
twins [3-5]. Lastly women who deliver twins at less than 34 weeks' have an
increased risk of preterm birth in future pregnancies .
Signs and Symptoms of Preterm Labor
Regular or frequent contractions
(tightening of the uterus), equal to or greater than 6 times in an hour.
Sometimes this feels like tightening of the belly.
Menstrual – like cramps or
Increase or change in vaginal
discharge (watery, mucus, or bloody)
Leakage of clear water or
bleeding from the vagina
Call your doctor if you notice
any of the above signs or symptoms. It is often difficult to tell the
difference between true preterm labor and false labor . The diagnosis of
preterm labor is usually made if there are regular contractions with effacement
(thinning) of the cervix to greater than or equal to 80% and /
or opening of the cervix to at least 2 centimeters.
What Causes Preterm Labor?
Spontaneous (unprovoked) preterm labor may
result from several causes including infection, inflammation, vascular
disease (poor blood supply to the uterus and placenta) , an overstretched
uterus, and abnormalities of the cervix . The cause of many preterm
births is never found 
Prevention of Preterm Labor
intramuscular and long term use of oral medications to stop contractions
(tocolytics) are not recommended for the prevention of preterm labor in multiple
pregnancies because these treatments are either ineffective and/or may cause
harm [7-11] Cervical cerclage (stitching the cervix closed) is also not
recommended in multiple pregnancies except in specific circumstances
However, vaginal progesterone may
be effective in reducing bad outcomes in women with a twin pregnancy and a
cervical length of 25 mm or less . Cervical
pessaries, small ring-shaped
devices which are inserted around the cervix,
may also be effective in reducing bad outcomes
in women with a twin pregnancy
and a cervical length of less than 38mm .
If there is enough time the
babies can be given a medication (corticosteroid) to help the lungs mature and
reduce other complications of being born prematurely. A shortened cervix
is a strong predictor of preterm delivery in twin pregnancies . The graph below
shows how the risk of preterm delivery begins to increase rapidly as the cervix
shortens to less than 25 mm.
Some health care providers use the cervical length and the
fetal fibronectin test to select twin pregnancies at high risk for preterm
delivery for treatment with corticosteroids before the mothers have
gone into preterm labor .
Reviewed by Mark Curran, M.D. FACOG
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