How is preterm labor prevented?
Premature labor, preterm delivery, and the
delivery of an infant <1,500 grams are the most significant risks to the
fetus. Medications that have α-adrenergic agonist proper-ties (e.g., ketamine
and phenylephrine) can increase uter-ine vascular tone and should be avoided, if
possible. The potent inhaled anesthetic agents decrease uterine tone and
inhibit uterine contractions and may, therefore, be benefi-cial. No study,
however, has ever documented that any par-ticular anesthetic agent or technique
is associated with a higher or lower incidence of miscarriage or preterm labor.
The greatest risk for preterm labor occurs when there is uter-ine manipulation,
as occurs during gynecologic procedures.
The lowest risk for preterm labor occurs during
the second trimester.