Pregnancy

Heartburn, Nausea, Vomiting During Pregnancy
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The prevention of aspiration and aggressive control of
acid secretion are very important in women undergoing
general anesthesia at the time of delivery. Since
the pH of the gastric aspirate is the important factor
determining the severity of chemical pneumonitis, the
thrust of preventing aspiration pneumonia is aimed
at raising the pH of the gastric secretions. Antacids,
H 2
antagonists and omeprazole may be effective in
this acute setting. Promotility drugs, such as metaclopramide
may improve gastric emptying during labor,
help prevent aspiration and are not toxic to the
fetus. 10
Nausea and Vomiting During Pregnancy
The single most common gastrointestinal complaint
in pregnancy is nausea, occurring in 50% to 90% of
women. Additionally, vomiting is an associated problem
in 25% to 55% of pregnancies. 11 Vomiting is most
common in the first trimester, peaking around 10 to 15
weeks gestation, and subsiding by 20 weeks gestation.
Nausea and/or vomiting is often the initial indication
that a patient is pregnant. Symptoms usually occur in
the early morning (“morning sickness”) and improve
later in the day. Nausea and vomiting during pregnancy
usually is a self-limited problem, disappearing
by the fourth month of pregnancy. The prognosis for
the mother and infant is excellent. There is no correlation
with the complications of pregnancy including
diabetes, hypertension, proteinuria, preeclampsia
and anemia. In addition, there are no increased risks
of low birth weight infants, increased fetal deaths, or
increased congenital malformations. There is speculation
that nausea and vomiting is a good prognostic
sign in pregnancy and that women who experience it
are less likely to have miscarriages or undergo premature
labor. This symptoms complex is more common
in primigravidas, younger women (especially
less than 20 years of age), less educated individuals,
overweight patients and non-smokers. 12
The etiology of nausea and vomiting during pregnancy
is still unknown. Alterations in gastric motility
and gastric tone due to elevated levels of progesterone
have been implicated. Animal studies show that progesterone
is a potent inhibitor of gastric antral contractions.
13 Premenopausal women have slower gastric
emptying rates than men and post-menopausal women
suggesting a hormone acting to inhibit gastric emptying.
14 Only limited studies of gastric function have
been performed in pregnant women. The few gastric
emptying studies, using scintigraphy, have employed
liquid meals and show no delay in emptying in the first
and second trimesters of pregnancy. However, these
studies were not performed with solid meals or when
the patients were nauseated. Animal studies show that
the there is a delay in gastric emptying during the third
trimester of pregnancy. This delayed emptying persists
in the immediate post-partum period but returns
to normal by four days after delivery, suggesting that
this pregnancy-induced gastroparesis is from gastric
motor dysfunction and not secondary to the effects of
an enlarged uterus. More recently, studies using cutaneous
EGG have found an increased prevalence of
gastric dysrhythmias such as bradygastria and tachygastria,
in patients with nausea. 15 These gastric dysrhythmias
correlated with nausea during pregnancy
and resolve during the post-partum period.
Animal studies show that
pregnancy delays small
bowel transit and slows the
migrating motor complex.
Another contributing factor to nausea and vomiting
may be delayed small bowel transit. Animal studies
show that pregnancy delays small bowel transit and
slows the migrating motor complex. Using the lactulose
breath test, studies in women during the third
trimester of pregnancy have confirmed delayed small
bowel transit which reverted to normal after completion
of the pregnancy. 16
Psychological factors may also contribute to nausea
and vomiting during pregnancy. Several studies have
shown that these symptoms are more common in
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