This is from the march of dimes website
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caffeine in pregnancy
safety of caffeine consumption during
pregnancy is controversial. Some studies
suggest that modest caffeine intake of
less than two average cups (defined below)
of coffee per day presents a slight risk
to the embryo or fetus, but others do not.
There is stronger evidence that larger
daily amounts of caffeine during pregnancy
may increase the risks of miscarriage,
preterm delivery and low birth weight, but
no solid proof.
High caffeine intake during pregnancy
should be avoided. Individual sensitivity
to caffeine may vary for both pregnant
women and developing fetuses, and risks of
moderate caffeine consumption are not
clear. Women trying to become pregnant
may conceive sooner if they limit caffeine
intake to moderate amounts. To minimize
infants’ exposures to caffeine,
breastfeeding women can avoid very high
caffeine intake.
General effects of caffeine
caffeine is a stimulant that is naturally
produced by a variety of plants. Natural
or synthetic caffeine is present in many
foods and beverages, and some
medications.
Caffeine usually enters the central
nervous system within fifteen minutes of
consumption. It slightly increases both
blood pressure and heart rate. Caffeine
also stimulates urination and thus reduces
body fluid levels – an effect considered
undesirable during pregnancy, when
adequate hydration is important.
Caffeine in coffee, tea and other
products
the caffeine content of a serving of
coffee or tea depends on the beans or
leaves used, serving size, and the method
of preparation. An 8-oz. Cup of brewed
coffee averages 150 milligrams (mg) of
caffeine. Instant coffee contains less.
Black tea averages 80 mg per 8-oz. Cup.
Green tea contains less. A 12-oz.
Caffeinated soft drink may contain 30-60
mg. (see the table below for more
specific values.)
other sources of caffeine include
chocolate, chocolate syrup, hot cocoa, and
certain medications. Amounts differ
greatly from one such source to another.
Chocolate or cocoa generally has very low
caffeine content. Medications containing
caffeine include some formulations for
pain relief, migraine, the common cold,
diuretic purposes, and delaying sleep.
Unlike foods and beverages, fda-approved
medications carry labels that say how much
caffeine they contain. Some “dietary
supplements” may contain caffeine, but
are not required to say how much.
Caffeine’s effects on fertility
some studies have found a link between
high levels of caffeine consumption by
women and delayed conception. Those who
consumed more than 300 mg of caffeine per
day were twice as likely to have
conception delayed for a year or more.1
another study also linked high caffeine
intake to delayed conception, but only in
women consuming 500 mg or more (about four
cups of coffee) per day.2
caffeine’s effects on the developing
fetus
caffeine easily passes from mother to
fetus through the placenta. A developing
fetus may have higher, sustained blood
levels of caffeine than its mother because
of immature metabolism.3 a few studies
have shown that even moderate caffeine
consumption affects fetal heart rate and
movement patterns.3 a pregnant woman’s
ability to metabolize caffeine slows as
pregnancy progresses, so some of its
effects may increase later in pregnancy.
Some studies have found that pregnant
women who consumed large quantities of
caffeine (five or more cups of coffee a
day) were twice as likely to miscarry as
those who consumed less, while fewer or no
effects were seen at lower levels of
caffeine consumption.4, 5 a detailed
analysis of caffeine's reported effects on
pregnancy outcome can be found at
motherisk.Org.
Caffeine’s effects on newborns and
infants
high caffeine consumption during pregnancy
may shorten gestation and lower birth
weight.6 both effects appear modest in
terms of days and ounces, but may be
important to an infant already compromised
by prematurity or fetal growth
restriction. Such effects have not been
consistently linked to moderate
consumption.7
a reported link between heavy maternal
caffeine intake during pregnancy and
increased risk of sids8 has not been
supported by further studies.9
breast milk can transfer caffeine from
mother to baby. Very high caffeine intake
by a nursing mother may make her baby
irritable, with disturbed sleep cycles,
but this is not known to occur from
ordinary food and beverage caffeine
intake, or without use of medications
containing caffeine.
Caffeine in beverages and chocolate10
item milligrams of
caffeine
average range
coffee (8-oz. Cup)
brewed, drip method
brewed, percolator
instant
184
128
104
96-288
64-272
48-192
tea (8-oz. Cup)
brewed, major u.S. Brands
brewed, imported brands
instant
iced (12-oz. Glass)
64
96
48
70
33-144
40-176
40-80
67-76
caffeinated soft drinks
(12 oz.) 36 30-60
hot cocoa (12 oz.) 6.4 3.2-32
chocolate milk beverage
(8 oz.) 5 2-7
milk chocolate (1 oz.) 6 1-15
dark chocolate, semi-sweet
(1 oz.) 20 5-35
baker's chocolate (1 oz.) 26 26
chocolate-flavored syrup
(1 oz.) 4 4
source: u.S. Fda and national soft drink
association
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