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Original Article
JOURNAL OF WOMEN’S HEALTH
Volume 18, Number 9, 2009
ª Mary Ann Liebert, Inc.
DOI: 10.1089=jwh.2008.1186
Caffeine’s Implications for Women’s Health and Survey
of Obstetrician-Gynecologists’ Caffeine Knowledge
and Assessment Practices
Britta L. Anderson, B.A.,1,2 Laura M. Juliano, Ph.D.,2 and Jay Schulkin, Ph.D.1
Abstract
Objective: Caffeine has relevance for women’s health and pregnancy, including significant associations with
spontaneous abortion and low birth weight. According to scientific data, pregnant women and women of
reproductive age should be advised to limit their caffeine consumption. This article reviews the implications of
caffeine for women’s psychological and physical health, and presents data on obstetrician-gynecologists’ (obgyns) knowledge and practices pertaining to caffeine.
Methods: Ob-gyns (N ¼ 386) who are members of the American College of Obstetricians and Gynecologists’
Collaborative Ambulatory Research Network responded to a 21-item survey about caffeine.
Results: Although most knew that caffeine is passed through breast milk, only 24.8% were aware that caffeine
metabolism significantly slows as pregnancy progresses. Many respondents were not aware of the caffeine
content of commonly used products, such as espresso and Diet Coke, with 14.3% and 57.8% indicating amounts
within an accurate range, respectively. Furthermore, ob-gyns did not take into account large differences in
caffeine content across different caffeinated beverages with most recommending one to two servings of coffee or
tea or soft drinks per day. There was substantial inconsistency in what was considered to be ‘‘high levels’’ of
maternal caffeine consumption, with only 31.6% providing a response. When asked to indicate the risk that high
levels of caffeine have on various pregnancy outcomes, responses were not consistent with scientific data. For
example, respondents overestimated the relative risk of stillbirths and underestimated the relative risk of
spontaneous abortion. There was great variability in assessment and advice practices pertaining to caffeine.
More than half advise their pregnant patients to consume caffeine under certain circumstances, most commonly
to alleviate headache and caffeine withdrawal.
Conclusions: The data suggest that ob-gyns could benefit from information about caffeine and its relevance to
their clinical practice. The development of clinical practice guidelines for caffeine may prove to be useful.
Introduction
C
affeine (1,3,7-trimethylxanthine), a mild central nervous system (CNS) stimulant, is the most widely used
behaviorally active drug in the world. Caffeine is ingested
from various sources, including coffee, tea, soft drinks, energy
drinks, foods, dietary supplements, and medications (Table 1).
In the United States, more than 85% of adults and children,
and 68% of pregnant women consume caffeine on a regular
basis.1 Mean daily caffeine intake has been estimated to be
about 280 mg among adults2 and 125 mg among pregnant
women in the United States.1
Caffeine has important clinical implications in the context
of women’s emotional and physical health as well as preg-
nancy outcomes. Physicians and particularly obstetriciangynecologists (ob-gyns), due to their expanding role as primary care providers,3 may benefit by having background
knowledge about caffeine and its clinical implications. However, little is known about ob-gyn’s general knowledge about
caffeine, assessment of caffeine use, and recommendations
given to patients.
Clinical implications of caffeine
Caffeine may affect individuals seeking medical care, and
women in particular, in a variety of clinically significant ways.
Caffeine produces various CNS and peripheral nervous system effects, primarily via antagonism of A2A and A1 adenosine
1
Research Department, American College of Obstetricians and Gynecologists, Washington, D.C.
Department of Psychology, American University, Washington, D.C.
2
1457
1458
ANDERSON ET AL.
Table 1. Caffeine Content of Common Caffeinated Products
Serving Typical
caffeine
size
(volume or content Range
(mg)
(mg)
weight)
Beverages
Coffee
Brewed=drip
8 oz
Instant
8 oz
Espresso
1 oz
Decaffeinated
8 oz
SBKs drip
12 oz
SBKs cappuccino
12 oz
SBKs espresso
1 oz
SBKs bottled frappuccino
9.5 oz
SBKs decaffeinated
12 oz
Tea
Brewed
8 oz
Instant
8 oz
Canned or bottled
12 oz
Soft drinks
Typical caffeinated
12 oz
Mountain Dew=Diet Mt. Dew
12 oz
Diet-coke
12 oz
Dr. Pepper=Diet Dr. Pepper
12 oz
Pepsi-Cola
12 oz
Diet Pepsi
12 oz
Coke Classic
12 oz
Sunkist
12 oz
Dr. Pepper=Diet Dr. Pepper
12 oz
Barq’s Root Beer
12 oz
A & W Root Beer
12 oz
7UP=Diet 7UP
12 oz
Sprite=Diet Sprite
12 oz
Canada Dry Ginger Ale
12 oz
Energy drinks
Typical amount
Varies
Red Bull
8.3 oz
Rockstar
16 oz
Tab
10.5 oz
Cocoa=hot chocolate
6 oz
Chocolate milk
6 oz
Caffeinated water
16.9 oz
133
93
70
5
260
75
75
85
20
71–280
27–173
60–95
0–13
53
40
20
40–120
13–47
8–32
40
55
47
41
38
36
35
41
41
23
0
0
0
0
22–69
Varies 50–505
80
160
95
7
2–10
4
2–7
60
60–200
Serving
size
(volume or
weight)
Typical
caffeine
content
(mg)
Foods
Chocolate
Hershey’s Chocolate Bar
1.55 oz
9
Hershey’s Special Dark
1.45 oz
18
Miscellaneous food
Dannon Coffee Yogurt
6 oz
30
SBKs Classic Coffee Ice Cream
4 oz
30
Powerbar Tangerine Powerge
41 g
50
Jolt Caffeinated Gum
1 stick
33
Stay-Alert Caffeinated Gum
1 stick
100
Penguin Peppermints
1 mint
7
Prescription medications
Headache=migraine=pain
Fiorinal
2 capsules
80
Fioricet=Esgic=many others
2 tablets
80
Cafergot
2 tablets
200
Norgesic
2 tablets
60
Over-the-counter medications
Stimulants
Vivarin
1 tablet
200
No-Doz=No-Doz Max. Strength
1 tablet
100 or 200
Analgesics
Anacin Advanced Headache
2 tablets
130
Excedrin Extra Strength
2 tablets
130
Menstrual pain relief=diuretics
Diurex Water Pills
2 tablets
100
Midol Menstrual Complete
2 caplets
120
Pamprin Max
2 caplets
130
Dietary supplements/weight loss products
Dexatrim Max
1 caplet
50
Hydroxycut Weight Loss Formula 2 caplets
200
Leptopril
2 capsules
220
Metabolife Ultra
2 caplets
150
Metabolife Weight Management
2 tablets
101
Stacker 2
1 capsule
253
Twinlab Ripped Fuel
2 capsules
220
Swarm Extreme Energizer
1 capsule
300
Xenadrine Efx
2 capsules
200
Sources: Juliano LM and Griffiths RR: Caffeine. In Substance Abuse: A Comprehensive Textbook, Fourth Edition. Lowinson JH, Ruiz P, Millman
RB, Langrod JG Baltimore: Lippincott Williams & Wilkins; 2005. McCusker RR, Fuehrlein B, Goldberger BA, Gold MS, Cone EJ: (2006a)
Caffeine content of decaffeinated coffee. J Anal Toxicol. 2006;30(8):611. McCusker RR, Goldberger BA, and Cone EJ: Caffeine content of
specialty coffees. J Anal Toxicol. 2003;27(7):520. Caffeine values for all brand name products were obtained directly from product labels, or the
manufacturer’s website or customer service department. SBK, Starbucks.
receptors.4 It produces positive subjective effects (e.g., happiness, alertness) at low to moderate doses (e.g., <200 mg)
and negative subjective effects (e.g., jitteriness) at higher doses
(e.g., >200 mg).5 The potential for caffeine to produce insomnia6 and anxiety7 is well documented, and both of these
problems occur at much higher rates in women.8,9 There are
also a number of physiological effects of caffeine that may
pertain to patient care, including increased blood pressure,
gastric acid secretions, colonic activity, urine volume, calcium
excretion, and increased levels of adrenocorticotropic hormone (ACTH), insulin, and cortisol.5 Heavy caffeine use
(>300 mg per day) also has been shown to be associated with
shorter menses and shorter menstrual cycles.10
The average half-life of caffeine is 4–6 h; however, there is
as much as a 10-fold difference in metabolism across indi-
viduals,11 with metabolism slowed by oral contraceptives12
and hastened by cigarette smoking.13 Furthermore, caffeine
metabolism is slower during the luteal phase relative to
the follicular phase of the menstrual cycle.10 Due to hormonal influences, caffeine metabolism slows during the second and third trimesters of pregnancy,14 which can lead to
elevated caffeine levels in women who maintain their usual
pre-pregnancy intake of caffeine. Elevated levels of caffeine
(as low as 250 mg, according to the DSM-IV-TR) can produce caffeine intoxication symptoms (e.g., heart arrhythmias,
nervousness) and other physical and psychological consequences,15 as well as allow for greater fetal exposure to caffeine.
Caffeine metabolism is very slow among fetuses and neonates
(i.e., 80–100 h half-life) due to immature liver systems, which
don’t fully develop until around 6–8 months of age.16
CAFFEINE AND WOMEN’S HEALTH
The potential for caffeine to produce physical dependence
is well-documented even at relatively low daily doses (e.g.,
100 mg per day).17 This could have important clinical implications, especially for pregnant women who may abruptly
stop using caffeine due to medical advice, health concerns,
nausea, or requirements of medical tests (e.g., 3-h glucose
challenge test). In fact, in one study of pregnant women, 54%
of those who ceased caffeine use reported withdrawal symptoms, and 26% of those with withdrawal symptoms reported
that these symptoms significantly interfered with their daily
functioning.18 Symptoms of caffeine withdrawal (e.g., headache, fatigue, difficulty concentrating, mood disturbances,
and flu-like symptoms17) could be misattributed to other
causes, including pregnancy symptoms. Furthermore, caffeine abstinence has been identified as a significant cause
of post-operative headaches19 and has been documented in
neonates after exposure to high doses of caffeine in utero.20,21
The International Classification of Diseases (ICD-10) recognizes a caffeine substance dependence syndrome, which comprises a cluster of symptoms indicative of problematic use of
a drug.22 Individuals meeting criteria for substance dependence on caffeine, including pregnant women, have been
identified.18,23
It is also important for health care providers to recognize
that caffeine can interact with commonly prescribed medications (e.g., benzodiazepines, cimetidine)12 and exacerbate
certain medical conditions (e.g., urinary incontinence, anxiety).24 It is used therapeutically as a respiratory stimulant in
neonates25 and as an analgesic adjuvant (e.g., Fioricet, Excedrin).26,27 Interestingly, epidemiological studies have identified a potential protective effect of caffeine and=or coffee
consumption in the risk of developing Parkinson’s disease,
liver disease, and Type II diabetes.28–30 There is no conclusive
evidence that caffeine negatively affects bone density in
postmenopausal women31,32 or fibrocystic breast disease,33–35
or increases breast cancer risk.36
Caffeine and pregnancy
There has been a substantial amount of research on caffeine
consumption and pregnancy outcomes. Caffeine readily
crosses the placental barrier and is distributed to all fetal tissues, including the CNS,14 allowing for the fetus to be exposed
to caffeine at levels similar to the mother’s. A recent large scale
study and a meta-analysis of previous studies suggest that
maternal caffeine use increases the rate of spontaneous abortion in a roughly dose-dependent fashion.37,38 Associations
between high caffeine use and decreased fecundity and reduced fetal growth have also been observed,39,40 including a
recent study that showed that reduced fetal growth was associated with consumption of as little as one to two cups of coffee
per day.41 It has been suggested that individual differences in
the CYP1A2 gene, which is involved in caffeine metabolism,
may interact with caffeine exposure in influencing the risk of
pregnancy loss and other negative pregnancy outcomes.42,43
The most consistent generality to emerge is that, when caffeine is associated with negative pregnancy outcomes, it is typically among women who consume high doses of caffeine.40
Caffeine consumption recommendations
Comprehensive scientific reviews of research on caffeine
and pregnancy have concluded that reproductive aged
1459
women should consume no more than 300 mg caffeine per
day.39,40 In line with such recommendations, governmental
agencies in North America and Europe have made statements
regarding safe consumption levels during pregnancy. Health
Canada44 and the American Dietetic Association45 advises
that pregnant women consume no more than 300 mg caffeine
per day, while the Food Standards Agency of the United
Kingdom46 recently lowered their recommended upper limit
to 200 mg per day for pregnant women. Presently, neither
the American Medical Association nor the American College
of Obstetricians and Gynecologists (ACOG) has put forth
guidelines for caffeine consumption in pregnant women.
Physicians’ knowledge and advice about caffeine
No previous studies have examined ob-gyns’ knowledge
and assessment practices pertaining to caffeine despite the
fact that most women consume caffeine, caffeine can have
important clinical implications for patients, and scientific reviews have concluded that reproductive-aged women should
limit consumption to 300 mg of caffeine per day or less.39 In
fact there has been only one published report pertaining to
physician’s recommendations pertaining to caffeine, which
was conducted over two decades ago and consisted of one
question.47 In this survey, medical specialists from two geographical regions were asked to check medical conditions for
which they think patients should be advised to reduce or
eliminate caffeine use. The most common conditions for
which reduction or cessation of caffeine was advised were
palpitations, arrhythmias, anxiety and insomnia. Furthermore among a sub-sample of 38 ob-gyns who were surveyed,
79% and 68% recommended caffeine reduction or cessation
for fibrocystic disease and pregnancy, respectively.
This report describes the first comprehensive survey to
examine knowledge and beliefs about caffeine among obgyns as well as their assessment and advice practices pertaining to caffeine use in pregnant and non-pregnant women.
Methods
Participants
A total of 785 Fellows of the ACOG were invited to participate in a cross-sectional survey study that asked about
their beliefs and knowledge of caffeine’s effects and their assessment and advice to pregnant and non-pregnant patients
concerning caffeine use. Participants were all members of
ACOG’s Collaborative Ambulatory Research Network
(CARN), a group of ACOG Fellows who agree to participate
in four to six surveys every 12 months. CARN members are a
representative sample (by age, gender, and geographic location) of the ACOG membership, of which over 90% of ob-gyns
in the United States are members. Half of CARN was randomly selected for this survey sample. The first mailing was
sent in June 2007, and second and third mailings were sent to
non-responders between July and August 2007.
Survey questions
All questions were developed for this study due to the lack
of previous survey studies on the topic.
Demographics and personal caffeine consumption.
Demographic questions included gender, age, practice status
1460
(practicing=retired), practice focus (e.g., obstetrics, gynecology, maternal fetal medicine), and geographical location of
practice. To assess whether personal consumption was related
to practice patterns as has been shown in previous research,48
ob-gyns were asked to report their typical consumption of
caffeinated beverages (average weekly number of servings of
coffee, tea, soft drinks, or other, and the typical serving size).
Caffeine knowledge. Ob-gyns were asked to estimate the
number of milligrams of caffeine in the following caffeinated
beverages: an 8-oz cup of coffee, a shot of espresso, a 12-oz can
of Diet Coke, and an 8-oz cup of black tea, and were asked
the number of servings of caffeinated beverages that are safe
for pregnant women to consume. They were asked whether
caffeine is passed through breast milk (true=false). They were
asked whether the rate of caffeine metabolism stays the same
or changes during the menstrual cycle and whether caffeine metabolism becomes faster, slower, or stays the same
throughout pregnancy. Ob-gyns were asked what they considered to be ‘‘high levels of maternal caffeine consumption
(in mg)’’ and to rate the degree to which high levels of caffeine
consumption increases the risk of various birth complications
on a scale from 0 (no increased risk) to 10 (substantial increased risk) and to indicate what they considered to be ‘‘high
levels of maternal caffeine consumption’’ (in mg=day). Physicians gave separate ratings for each of the following pregnancy outcomes: overall health of fetus, low birth weight,
shorter gestational age, spontaneous abortion, congenital
abnormalities, nausea, stillbirths, or long-term health of the
child. Ob-gyns were asked whether they consider caffeine to
be a drug of clinical dependence and to indicate the minimum
amount of caffeine consumption per day that can lead to withdrawal symptoms if someone abruptly stops using caffeine.
Caffeine assessment and advice. Ob-gyns were asked
about the following: if and when they discuss caffeine use,
methods they use to assess caffeine consumption, caffeinated
products they routinely ask about, how frequently they initiate a conversation about caffeine use, what advice they
usually give their pregnant patients, and if they ever advise their pregnant patients to consume caffeine. Finally,
they indicated which of their non-pregnant patients (adolescent patients=patients of childbearing age=perimenopausal
patients=postmenopausal patients) they ask about caffeine
consumption.
Statistical analysis
Analyses were conducted using SPSS 15.0 (SPSS Inc.,
Chicago, IL) with alpha set at p < 0.05. For the analysis of
assessment practices relating to pregnancy, only physicians
who were currently practicing (n ¼ 379) and treating (n ¼ 332)
pregnant patients were included. Due to large variability in
response rates across questions, raw numbers are presented
with percentages for added clarity.
Results
Demographics
A total of 386 ob-gyns returned the survey, a response rate
of 49.1%. A comparison of responders and non-responders
indicated no differences in age or gender. The sample was
ANDERSON ET AL.
predominantly white (62.7%) with an average age of 48.6
(SD þ 10.1) years, which is representative of the fellows of
ACOG. The majority of respondents practice general obstetrics and gynecology (78.9%). Just under half (40.5%) also
provide primary care to their adolescent, women of childbearing age, or post menopausal patients.
No meaningful differences were observed based on age,
gender, or other demographic variables, and thus all data is
reported for the sample as a whole.
Personal use of caffeine
Of the 83.9% (n ¼ 324) who provided information about
their caffeine consumption, 90.1% (n ¼ 292) reported consuming caffeine on a weekly basis with an estimated mean
of 1188.2 mg=week (SD ¼ 1046.3) ranging from 68 to
6016 mg=week.
Knowledge about caffeine
When asked to estimate the amount of caffeine in milligrams contained in common caffeinated beverages, responses
were considered correct if they were within a wide range
of possible values for each type of beverage. As shown in
Table 2, respondents largely over estimated the amount of
caffeine in a serving of espresso with only 14.3% (18=126)
providing a value in the accepted range24 (i.e., 60–95 mg).
Accurate estimates for a serving of coffee (i.e., 71–280 mg),
tea (i.e., 40–120 mg), and Diet Coke (i.e., 22–69 mg) were
provided by 66.70% (92=138), 63.90% (85=133), and 57.80%
(78=135) of respondents, respectively.
When asked to report what was considered to be ‘‘high
levels of maternal caffeine consumption,’’ 15.8% (61=386)
wrote in that they did not know and 52.6% (203=386) left the
question blank. Of the 31.6% (122=386) that did provide an
answer, the mean response was 242.2 mg (SD ¼ 215.7), with a
median of 200 mg. Only 13.2% (51=386) of all participants and
41.8% (51=122) of those who provided an answer indicated
300 mg or above.
When asked to rate the effect of high maternal caffeine
consumption on various pregnancy outcomes, low birth
weight had the highest mean response (greatest increase risk;
M ¼ 4.5, SD ¼ 2.5) and congenital abnormalities had the
lowest mean response (least increased risk; M ¼ 1.9, SD ¼ 2.1;
Fig. 1). The mean response for spontaneous abortion was
3.62 (SD ¼ 2.88). Low birth weight was rated significantly
higher than spontaneous abortion (t ¼ 5.28, p < 0.001).
As shown in Table 2, 96.0% (313=326) of those who provided an answer correctly indicated that caffeine can be passed through breast milk. However, only 24.8% (77=310)
indicated that the metabolism of caffeine slows as women
progress through pregnancy, with the majority indicating that
the rate of metabolism becomes faster (39.7%, 123=310) or
stays the same (35.5%, 110=310). Furthermore, only 46.3%
(143=309) indicated that caffeine metabolism changes during
different stages of the menstrual cycle.
Only 34.2% (132=386) provided an estimate for the minimum daily amount of caffeine consumption that will lead to
withdrawal symptoms when someone abruptly stops using
caffeine, the mean response was 197.01 (SD ¼ 209.49), though
there was great variability in responses. Nearly half of all
respondents (49.2%, 65=132) incorrectly overestimated the
amount that can cause physical dependence.
CAFFEINE AND WOMEN’S HEALTH
1461
Table 2. Empirical Data Compared with Ob-Gyns’ Responses to Questions
about Caffeine and Women’s Health
Responses of ob-gyns
in the present study
Empirical data
What is the minimum
daily amount that will
cause withdrawal?
Is caffeine a drug of
clinical dependence?
73% said yes
ICD-10 recognizes
caffeine as a drug
of dependence; the
DSM-IV does not.15,22
Yes, caffeine is ingested
by an infant through
a mother’s breast milk.39
Yes, metabolism slows
during the luteal phase.60
Is caffeine passed
through breast milk?
Does caffeine metabolism
change throughout the
menstrual cycle?
Does caffeine metabolism
change throughout
pregnancy?
Yes, the half-life of caffeine
slows from an average
of 5 h during month
4 to 18 h by month 9.14
Estimate range
for size and type
of product.2
How many mg of caffeine
are in the following:
8-oz cup of coffee
One shot of espresso
12-oz can of Diet Coke
8-oz cup of tea
71–280 mg
60–95 mg
22–69 mg
40–120 mg
Almost three-fourths of respondents (73%, 265=365) consider caffeine to be a drug of clinical dependence. Only 5.4%
(21=386) did not respond to this question.
Assessment of caffeine use
Notably, 58.2% (188=323) reported that they always discuss
caffeine consumption with their pregnant patients and 31.3%
(101=323) never do. Ten and a half percent (34=323) reported
FIG. 1.
Mean ¼ 197 (SD ¼ 210)
As little as 100 mg=day
can cause withdrawal59
96.0% said yes
46.3% said yes
24.8% said caffeine metabolism slows
39.7% said caffeine metabolism increases
35.5% said caffeine metabolism stays the same
Mean (SD)
110.5 mg
142.8 mg
70.5 mg
70.0 mg
(84.3)
(156.9)
(70.7)
(80.8)
% within
estimated
range
% who
underestimated
% who
overestimated
66.70%
14.30%
57.80%
63.90%
27.5%
25.4%
8.9%
26.3%
2.2%
40.5%
33.3%
9%
discussing caffeine under certain patient circumstances, with
the following conditions indicated by respondents: osteoporosis, irregular heartbeat, insomnia, diabetes, hypertension,
poor weight gain, fetal arrhythmia, vascular disease, headaches, breast pain, and palpitations.
When asked when ob-gyns discuss caffeine consumption
with their pregnant patients, most participants indicated
doing so at patients’ first visit (64%, 218=386) or when the
pregnant patient brings up the topic of caffeine consumption
Ob-gyns’ rating of the impact that high caffeine use has on birth complications.
1462
(45.9%, 177=386). Twenty-five percent (97=386) discussed
caffeine consumption when discussing other drug use (e.g.,
alcohol, nicotine), and 18.4% (71=386) indicated that they
discuss caffeine consumption with their pregnant patients
when a ‘‘pregnant patient is complaining of what seem to be
caffeine-related effects’’ with the following types of effects
reported: headache, palpitations, breast tenderness, and difficulty sleeping.
When asked how often ob-gyns initiate a conversation
about caffeine consumption with their pregnant patients,
24.0% (78=325) always do, 20.0% (65=325) often do, 26.2%
(85=325) sometimes do, and 23.1% (75=325) rarely do. Caffeine
consumption is most often assessed via a routine question
asked by the ob-gyn or a member of his=her staff (40.4%,
156=386), followed by assessment using questions on a form
(20.2%, 78=386). One-third (30.8%, 119=386) indicated that
they had no formal routine method. Most ob-gyns ask about
caffeine consumed from coffee (73.7%, 241=327), soft drinks
(71.8%, 234=326), and tea (62.0%, 202=326) but fewer ask
about energy drinks (38%, 124=326), foods (29.4%, 96=326),
medications (21.2%, 69=326), and energy aids (19.3%, 63=326).
However, 13.2% (43=326) indicated that they do not ask about
specific sources of caffeine.
The majority of respondents (64.5%, 238=369) reported that
they do not assess caffeine use in their non-pregnant patients.
Around one quarter assess caffeine use in adolescents, women
of child bearing age, perimenopausal, and postmenopausal
women (20.3%, 75=369; 28.7%, 106=369; 26%, 96=369; and
25.2%, 93=369, respectively).
Caffeine consumption advice
Most respondents reported that it is safe for pregnant
women to consume either one or two servings of coffee or
soft drinks or tea per day. To evaluate how consistent their
recommendations were across different products in terms of
caffeine exposure, all responses were converted to milligrams
amounts, and the differences among the various products
(coffee–soft drinks, coffee–tea, tea–soft drinks) were computed for each respondent. We chose a very liberal cutoff of a
100-mg or less difference to be considered to be a consistent
recommendation. Only 10.5% (29=277) of ob-gyns were consistent across coffee and tea, and 11.0% (31=282) across coffee
and soft drinks. However, 98.5% (271=275) were consistent
across tea and soft drinks.
Most ob-gyns indicated that they did not know what they
considered to be a ‘‘healthy daily intake’’ of caffeine for nonpregnant women (64.8%, 250=386) or left it blank (10.6%,
41=386). Of those who responded (24.6%, 95=386), the mean
amount reported was 199.3mg (SD ¼ 153.1) and responses
ranged from 0 to 1000 mg, with 87.4% (83=95) of responders or
21.5% (83=386) of all participants reporting an amount 300 mg
or below.
Participants were asked what advice they usually give their
patients about caffeine, one quarter (25.4%, 82=323) of obgyns tell their patients that research about caffeine’s effect in
pregnant women is largely inconclusive. Still, 31% (82=266)
wrote in a response that indicated that they tell their pregnant
patients to limit caffeine consumption to one drink=glass=
serving, 20% (53=266) recommend one to two servings per
day, and 18% (48=266) recommend two servings per day.
ANDERSON ET AL.
Only 2% (5=266) wrote in trimester specific advice for caffeine use. Only 11.3% (37=326) of respondents advise their
patients that ‘‘it is best to stop all caffeine consumption during
pregnancy.’’
Most participants indicated if they advise their patients to
consume caffeine (84.5%, 326=386). More than half of the respondents (61.7%, 201=326) advise some patients to consume
caffeine during pregnancy for the following reasons: alleviate
headaches (51.8%, 169=326), relieve caffeine withdrawal
symptoms (32.8%, 107=326), improve mood (2.8%, 9=326),
other (4.0%, 13=326; e.g., fatigue, constipation, low blood
pressure). Thirty-eight percent of respondents (125=326) indicated that they never advise their pregnant patients to
consume caffeine.
Discussion
Caffeine is a widely used drug that has many clinically
relevant physiological and psychological effects, some of
which are specifically related to women’s health and pregnancy outcomes. This is the first study to examine ob-gyn’s
knowledge and practices pertaining to patients’ use of caffeine.
Ob-gyn’s knowledge about caffeine
It appears that many ob-gyns are not aware of the caffeine
content of commonly used beverages. As shown in Table 2,
more than a third of respondents did not provide values
within a wide range of possible values for coffee, tea, and soft
drinks; with a tendency to overestimate the caffeine content of
soft drinks and underestimate the caffeine content of coffee
and tea. More than 85% of respondents either significantly
overestimated or underestimated the caffeine content of
espresso.
When ob-gyns were asked to define ‘‘high levels’’ of caffeine consumption there was great variability in their responses and 13.2% of all respondents indicated 300mg or
above. However, it is interesting to note that more than twothirds did not answer the question or wrote that they did not
know. Together, the wide variability, inaccuracy, and low
response rate suggest that physicians need guidance and information about acceptable levels of caffeine use for pregnant
women. Scientific reviews have concluded that pregnant
women should consume no more than 300 mg of caffeine per
day,45,46 while some recent studies suggest that no more than
200 mg may be a more appropriate cut off.
While the actual risk of caffeine causing adverse pregnancy
outcomes is a complicated and often discrepant body of literature, our data suggests that perhaps ob-gyns are overestimating the relative risk of stillbirths and underestimating
the relative risk of spontaneous abortion. Empirical evidence
is inconclusive about caffeine’s effect on many adverse pregnancy outcomes, however, research supports that spontaneous abortion and low birth weight are associated with caffeine
consumption.37,38,41,49–51 For example, a recent study found as
little as two cups of coffee per day is associated with an increased risk of spontaneous abortion,37 and one to two cups of
coffee per day is associated with low birth weight.41 The
ACOG has produced a Practice Bulletin on the Management
of Recurrent Early Pregnancy Loss for ob-gyns that states
that caffeine and other drugs ‘‘may act in a dose-dependent
CAFFEINE AND WOMEN’S HEALTH
fashion or synergistically to increase the rate of sporadic
pregnancy loss,’’ but is not associated with recurrent pregnancy loss.52
Although most respondents knew that caffeine is passed
through breast milk, fewer than one-fourth knew that caffeine
metabolism slows during pregnancy, and nearly 40% incorrectly answered that caffeine metabolism increases during
pregnancy. Because caffeine remains in the body longer during this period of slower metabolism, the physiological and
psychological effects of caffeine are likely to be exacerbated,
particularly for women in their final months of pregnancy.
A substantial amount of research supports that caffeine is a
drug of physical dependence,17 meaning that its cessation will
produce withdrawal symptoms. About three-fourths of obgyns indicated that they consider caffeine to be a drug of
clinical dependence. However, ‘‘clinical dependence’’ was not
operationalized, and some may have taken this to mean
physical dependence rather than a cluster of symptoms indicative of problematic drug use. Nevertheless, features of
clinical dependence (e.g., use despite harm, unsuccessful efforts to reduce consumption, tolerance) have been noted
among caffeine consumers across various studies.18,23,53 In
one recent study, a sample of pregnant women meeting criteria for substance dependence on caffeine was identified,18
and a caffeine dependence diagnosis predicted greater use of
caffeine during pregnancy despite being advised by their obgyn to eliminate caffeine.
Ob-gyns appeared to overestimate the amount of caffeine
exposure that is necessary to become physically dependent,
and thus experience withdrawal symptoms upon acute abstinence, with the mean response being about twice as much
caffeine as research has shown is necessary to produce
physical dependence. This along with the fact that over twothirds of the respondents failed to respond, suggests that
caffeine withdrawal is poorly understood by ob-gyns. It is
important that health care providers be aware that if a patient
abruptly stops consuming even relatively small amounts of
caffeine (i.e., 100 mg per day), as some pregnant women are
likely to do,18 they may experience caffeine withdrawal
symptoms such as headache, fatigue, difficulty concentrating,
mood disturbances and flu-like symptoms.17 Thus, it is recommended that when patients complain of such symptoms
physicians assess caffeine use and recent consumption patterns. Patients who would like to cease their caffeine use
should be advised to gradually reduce their caffeine consumption to reduce the severity of withdrawal symptoms.
There is no empirical data available to suggest a specific timeframe for reduction, but some have suggested that reducing
consumption by 10–25% every few days or so may be effective. Additional guidelines for reducing or eliminating caffeine can be found elsewhere.5
Assessment of caffeine use
Compared with other commonly used recreational drugs,
ob-gyns discuss consumption of caffeine, with their pregnant
patients less often. In our sample, 58% of ob-gyns discuss
caffeine, where other studies have reported that 97% discuss
alcohol54 and 98% discuss tobacco.55 There was little consistency in the methods, frequency, and timing of the assessment
of caffeine among ob-gyns. It is possible that ob-gyns do not
1463
believe that caffeine is an important topic to discuss and=or it
could be a result of the lack of practice guidelines pertaining to
caffeine. It is also possible that it is due to difficulty interpreting often conflicting research findings pertaining to caffeine associated health risks. Lastly, the amount of time
necessary to accurately assess caffeine exposure may present
another barrier.
When assessing caffeine use, most ob-gyns reported that
they ask about coffee, soft drinks, and tea; however, only 30%
ask about caffeine intake from food and 21% ask about
medications. A recent study estimated that 80.6% of pregnant
women consume caffeine from multiple sources with 36.7%
obtaining caffeine from all non-coffee sources.37 It is important to note that food and medications can be a significant
source of caffeine as shown in Table 1.
Some, though a minority, of our respondents discuss
caffeine use under specific patient circumstances including
insomnia, diabetes, hypertension, poor weight gain, fetal arrhythmia, vascular disease, headaches, breast pain, and palpitations and=or assess for caffeine use when pregnant patients
complain of what seem to be caffeine-related effects. Due to
caffeine’s well-established effects on sleep and anxiety,6,7 obgyns should assess caffeine consumption whenever patients
complain of sleep disruption or anxiety-related symptoms.
Women presenting with urinary incontinence may benefit
from advice to reduce or cease caffeine use.56 Caffeine use
should also be assessed in patients presenting with hypertension as it has been shown that caffeine can raise blood pressure
by 5–15 Hg systolic and 5–10 Hg diastolic in healthy adults.39
Symptoms of caffeine excess=intoxication and caffeine withdrawal have symptoms that overlap with many other health
conditions, including some pregnancy symptoms and ob-gyns
should keep these in mind as potential differential diagnoses.
For example, caffeine excess=intoxication should be considered
in differential diagnoses of conditions such as medication=
drug induced side effects (e.g., akathisia), substance withdrawal (e.g., benzodiazepines), hyperthyroidism, anxiety,
mania, insomnia, and pheochromocytoma. Caffeine withdrawal can mimic medication-induced side effects, migraine
and other headache disorders, viral illness, dehydration,
withdrawal from other drugs, and pregnancy symptoms.
Advice
Many ob-gyns in our study advise patients to limit caffeine
consumption to one or two servings of coffee or tea or soft
drinks per day. Thus, it does not appear that physicians are
taking into account the wide differences in caffeine content
across different products when providing advice to their patients. For example, the amount of caffeine in two servings of
coffee (roughly 266 mg) is about three times as much as the
amount of caffeine in two servings of soft drinks (roughly
80 mg). Knowledge of the various sources of caffeine and
variability across products should help physicians provide
consistent advice to their patients.
Thirty two percent of respondents reported that they
would never advise their pregnant patients to consume caffeine, while 50.8% of ob-gyns reported that they sometimes
advise their patients to consume caffeine. Reasons provided
included consumption to alleviate headache, withdrawal
symptoms, or mood. Indeed caffeine typically alleviates
1464
caffeine withdrawal symptoms including headache and poor
mood in about 30–60 min.17 There is evidence that caffeine
increases the effectiveness of analgesic medications in the
treatment of headache with more modest therapeutic effects
when given.26
Study limitations
As this was the first study of its kind, replication and
psychometric evaluation of the questionnaire is warranted.
Furthermore, the data collected is limited by self-report and
potential retrospective biases. This sample of ob-gyns reported using less caffeine than the typical American adult
caffeine consumer (i.e., 170 mg vs. 280 mg per day).2 It is
possible that individuals who chose to complete this survey
were more sensitive to issues pertaining to caffeine and thus
may use less caffeine than the general population. It is also
possible that our crude measurement of caffeine consumption
underestimated use, or respondents underreported their use.
At least one study has found that self-reported caffeine consumption has questionable validity.57 Furthermore, some of
the open ended questions had very low response rates.
However, the low response rates appeared to be question
specific and not a function of the location in the survey, which
may suggest a lack of knowledge rather than lack of desire to
complete the survey. The response rate for the survey was
49.1%, which is consistent with typical response rates for the
CARN group. There were no differences on any demographic
variable between those that returned the survey and the
CARN group at large. Furthermore, previous analyses have
been done to assess whether responses from CARN members
are different from responses from ACOG members in general,58 and have concluded that there are few, if any, differences between samples.
Conclusions
Although it is acknowledged that additional research is
needed to clarify limits of caffeine consumption during
pregnancy, major health reviews have suggested that pregnant women or women trying to conceive should limit their
caffeine consumption to no more than 300 mg per day. It is
acknowledged that physicians have limited time with patients and that other issues may take priority over routine
assessment of caffeine consumption. At the very least, it is
important for health care providers to be aware of the clinically relevant effects that caffeine has on physical and psychological health and to consider these effects when treating
patients. Furthermore, as obstetricians and gynecologists
continue to provide an expanding range of care to women,
their knowledge and awareness of caffeine’s general effects on
health and psychological well-being is becoming even more
significant to their practice.
Our study confirms that physicians frequently counsel
patients to reduce or eliminate caffeine use during pregnancy.
Among those who reported providing recommendations,
their advice is in line with current research recommendations,
that pregnant women limit their caffeine consumption to
300 mg per day (i.e., many said they advise limiting use to
one or two servings of coffee or tea or soft drinks per day).
However, there was great variability in what was considered
to be ‘‘high levels’’ or ‘‘safe levels’’ of caffeine use for pregnant
ANDERSON ET AL.
women and the data suggests that many simply do not know
an appropriate limit of caffeine for pregnant women. Ob-gyns
in our survey were unaware of the amount of caffeine in
various products, and they tended to limit their assessment of
caffeine exposure to caffeinated beverages. They were also
largely unaware that caffeine metabolism significantly slows
as pregnancy progresses as well as changes across the menstrual cycle, or that as little as 100 mg per day of caffeine can
result in withdrawal symptoms upon acute abstinence.
Future research should be aimed at education and assessment of physicians’ knowledge about caffeine and its clinical
implications for patients. We hope that this article serves to
increase knowledge of caffeine and its clinically relevant
pharmacological effects and recommend the development of
practice guidelines for ob-gyns and other health care providers.
Acknowledgments
This study was supported by the Maternal and Child
Health Bureau, Health Resources and Services Administration, Department of Health and Human Services (grant R60MC-05674).
Disclosure Statement
The authors have no conflicts of interest to report.
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Address correspondence to:
Britta L. Anderson, B.A.
Research Department
American College of Obstetricians and Gynecologists
409 12th Street, SW
Washington, DC 20024
E-mail: [email protected]
or
Laura M. Juliano, Ph.D.
Associate Professor of Psychology
American University
4400 Massachusetts Avenue NW
Washington, DC 20016
E-mail: [email protected]