Hyperstimulation or tachysystole are terms that define some of the ways
that the uterus can be overstimulated during labor. During the process
of labor and delivery, a mother will release endogenous oxytocin, which
stimulates uterine contractions and helps to progress the process of labor
and eventual delivery of a baby. However, in recent years, the use of
artificial oxytocin, marketed as "Pitocin," has become a widespread practice to induce labor in mothers who
are overdue or who are having poor labor progress.
It is well-known in medical literature that end-organ response to Pitocin
is dependent upon the mother, rather than the dosage used. Medical practitioners
must be careful to monitor the mother and baby to assure the well-being
of both. Continuous fetal heart rate monitoring, measurement of the strength
and duration of contractions, as well as response to signs of a bad reaction
to the use of Pitocin are prerequisites for the use of this drug; to fail
to monitor a mother and baby correctly is extremely dangerous.
When a mother is contracting, blood supply and oxygen are cut off between
the placenta and the baby momentarily. The baby can, in effect, "hold
his or her breath" during the contractions and rely on his or her
reserves in order to stay healthy during these periods of
lack of oxygen. However, when the uterus is contracting too frequently, strongly, or
without a return to normal "resting tone", a baby can begin
to become hypoxic. Much like a mountain climber who is acclimating to
higher elevations, the lack of oxygen, over time, can cause brain damage
as a baby is no longer able to tolerate the periods of lack of oxygen.
This, in turn, causes
brain damage and can lead to cerebral palsy.
New literature, in fact, has revealed that the threshold for tolerance
of too many contractions is lower than previously thought: in the American
Journal of Obstetrics and Gynecology (AJOG), two articles recently examined
the fact that 7 contractions in any 15 minute window of labor was independently
correlated with neonatal injury, and the fact that the presence of any
tachysystole during labor was also correlated with
neonatal injury. These articles by Hayes and Heuser confirm what we know about the physiological
responses of a mother and baby during labor, especially when Pitocin is
causing too many contractions.