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American Journal of Epidemiology
ª The Author 2009. Published by the Johns Hopkins Bloomberg School of Public Health.
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Vol. 169, No. 10
DOI: 10.1093/aje/kwp040
Advance Access publication April 2, 2009
Original Contribution
Maternal Consumption of Coffee and Caffeine-containing Beverages and Oral
Clefts: A Population-based Case-Control Study in Norway
Anne Marte W. Johansen, Allen J. Wilcox, Rolv T. Lie, Lene F. Andersen, and Christian A. Drevon
Initially submitted August 11, 2008; accepted for publication February 2, 2009.
A large, population-based case-control study of facial clefts was carried out in Norway between 1996 and 2001.
The study included 573 cases—377 with cleft lip with or without cleft palate and 196 with cleft palate only—and 763
randomly selected controls. Maternal consumption of coffee and other caffeine-containing beverages in early
pregnancy was recorded shortly after birth. Compared with that for no coffee consumption, the adjusted odds
ratios for cleft lip with or without cleft palate were 1.39 (95% confidence interval: 1.01, 1.92) for less than 3 cups
a day and 1.59 (95% confidence interval: 1.05, 2.39) for 3 cups or more. Coffee consumption was not associated
with risk of cleft palate only (for 3 cups vs. none, adjusted odds ratio ¼ 0.96, 95% confidence interval: 0.55, 1.67).
Tea consumption was associated with a reduced odds ratio of both cleft lip with or without cleft palate and cleft
palate only. There was little evidence of an association between caffeine exposure and clefts when all sources of
caffeine were considered. Adjustment for known confounding factors in general had minor effects on risk estimates. Still, the authors could not rule out the possibility of uncontrolled confounding by factors associated with the
habit of drinking coffee.
caffeine; cleft lip; cleft palate; coffee; pregnancy
Abbreviations: CI, confidence interval; CLP, cleft lip with or without cleft palate; CPO, cleft palate only.
Orofacial clefts are among the most common birth defects, and the prevalence in Norway (2.2 per 1,000 livebirths) is particularly high. The etiology of clefts is
complex and largely unknown. The high risk of recurrence
of clefts among first-degree relatives (as much as 56 times
the background prevalence) suggests a strong genetic component (1). However, environmental factors such as maternal
nutrition (2–4), vitamin supplements (5), smoking (6), and
binge alcohol consumption (7) also appear to contribute.
Coffee consumption is relatively high in Norway. In the
latest nationwide study, average coffee intake was half a liter
a day, with peak intake among those aged 40–60 years (8).
Data from animal studies suggest that large single doses of
caffeine may cause palatal clefts as well as other birth defects (9), although studies of coffee consumption in humans
have provided little evidence of teratogenic effects (10). In
a systematic review of 3 studies of orofacial clefts and caffeine, high coffee intake was associated with a slight in-
crease in risk (11). According to a recently published
article, maternal caffeine intake during pregnancy was associated with fetal growth restriction (12).
Coffee is a commonly consumed beverage among pregnant women, and even a small increase in malformation risk
could be a matter of concern. We used data from a populationbased case-control study to evaluate the association of maternal consumption of coffee and caffeinated beverages in
early pregnancy with the risk of delivering an infant with an
orofacial cleft.
MATERIALS AND METHODS
All infants born with facial clefts in Norway are treated at
government expense in surgical centers at university hospitals located in Oslo and Bergen. In collaboration with these
2 centers, we identified all babies born from 1996 to 2001
who were referred for treatment for either cleft lip with or
Correspondence to Anne Marte Wetting Johansen, Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, University of
Oslo, PO Box 1046, 0316 Oslo, Norway (e-mail: [email protected]).
1216
Am J Epidemiol 2009;169:1216–1222
Maternal Caffeine Consumption and Oral Clefts
without cleft palate (CLP) or cleft palate only (CPO). Controls were recruited during the same period by randomly
selecting approximately 4 births per 1,000 from the National
Medical Birth Registry (which includes all births in the
country). These births served as controls for both case
groups, with the target of 2 controls per case of CLP (nearly
4 controls for each case of CPO). Both cases and controls
were recruited during their first weeks of life.
Our present study was approved by the regional ethics
review board, the Norwegian Data Inspectorate, and the
US National Institute of Environmental Health Sciences
Review Board. All participating mothers provided informed
consent.
Participants
There were 676 women in Norway who delivered infants
requiring surgery for orofacial clefts during 1996–2001. We
excluded 24 mothers who did not speak Norwegian or
whose infant died after birth, leaving 652 eligible mothers.
Of these, 88% (n ¼ 573) agreed to participate. We randomly selected 1,022 control mothers of livebirths via the
national Medical Birth Registry within 6 weeks of delivery.
After excluding 16 who were not Norwegian speakers or
whose infant died, 1,006 mothers of controls were eligible,
of whom 76% (n ¼ 763) agreed to participate. Data on intake of coffee and other caffeinated beverages were available for all participating mothers of cases and controls. We
identified other birth defects among the cleft cases by using
3 data sources: the Medical Birth Registry (based on delivery records and hospital records from the first week of
life), medical records at the hospital performing the corrective surgery, and mother’s questionnaire. Accompanying
defects were reported for 17% of CLP cases and 40% of
CPO cases. Cases of clefts without accompanying defects
have been categorized as isolated clefts.
Data collection
Mothers completed a 32-page questionnaire covering demographic characteristics, reproductive history, and exposures during pregnancy (including smoking, alcohol
consumption, coffee intake, medication use, and occupational and household exposures). Median time from delivery
to completion of the questionnaire was 14 weeks for cases
and 15 weeks for controls. The questionnaire included items
on maternal consumption of caffeine-containing beverages
(coffee, tea, and soft drinks) during the first 3 months of
pregnancy. For each beverage, there was 1 question with 5
response categories: none, number of cups per day, number
of cups per week, number of cups per month, and number
of cups per year (without specifying the size of the cup).
An English translation of the questionnaire is available
online (http://www.niehs.nih.gov/research/atniehs/labs/epi/
studies/ncl/ncl_pregnancy_en.pdf).
Statistical methods
The risk of delivering offspring with an orofacial cleft
was estimated by odds ratios with 95% confidence intervals
Am J Epidemiol 2009;169:1216–1222
1217
in unconditional logistic regression models. All beverages
were summarized and were analyzed in the same way, as
follows. ‘‘Cups per day’’ was computed from reported number of cups consumed per day, per week (divided by 7), or
per month (divided by 30). Women who reported consuming
less than 1 cup per month were categorized as consuming
zero. The cups-per-day variable was analyzed as a continuous variable. Finally, a 3-category variable was created:
0 cups per day (reference category), more than 0 but less
than 3 cups per day, and 3 or more cups per day. Trends
across the categories were evaluated, with zero as the
reference.
An estimate of caffeine from all sources was computed
from the data on coffee, tea, and caffeinated soft drinks.
Caffeine content was estimated as 100 mg per cup of coffee,
40 mg per cup of tea, and 20 mg per cup of caffeinated soft
drink based on values from the Norwegian Health Authorities Web page (http://www.matportalen.no/Emner/Gravide
(in Norwegian)). Risk of clefts was evaluated per 100-mg
increase in caffeine intake (continuous variable) and for the
categories >100–<500 mg and 500 mg of caffeine relative to 0–100 mg.
Adjustments were made for potential confounders (factors associated with clefts in other studies, most of which
were also associated in our study), namely, dietary vitamin
A (quartiles), dietary folate (quartiles), folic acid supplement (400 lg/day, yes or no), vitamin supplement use
(yes or no), consumption of alcohol in early pregnancy
(number of drinks per sitting), smoking (ordinal linear with
5 categories: none; passive only; and 1–5, 6–10, and 11
cigarettes a day), nausea during the first trimester (yes or
no), employment in early pregnancy (yes or no), education
(ordinal linear with 6 categories), father’s income (ordinal
linear with 3 categories), and year of birth. Evaluations of
possible interactions with coffee intake were carried out for
use of folic acid supplements and smoking. In evaluating the
effects of coffee or tea separately, we adjusted for the other
(categorized as number of cups per day). Because CLP and
CPO are considered etiologically distinct outcomes, we conducted separate analyses for each (1). Separate analyses
were also performed for isolated clefts (i.e., excluding those
with accompanying defects). Because oral clefts are relatively rare birth defects, odds ratios are close approximations of relative risks. All statistical analyses were
performed by using SPSS 14.0 software (SPSS Inc.,
Chicago, Illinois).
RESULTS
Women who gave birth to infants with CLP were taller,
less educated, and less likely to work during the first trimester compared with mothers who gave birth to healthy
controls (Table 1). Compared with mothers of controls,
fewer mothers of CLP cases used a folic acid supplement,
and they were more often coffee consumers and smokers.
Fewer mothers of CLP and CPO cases drank tea compared
with mothers of controls (Table 1).
Maternal coffee consumption was associated with an increased risk of CLP. In the adjusted analyses, the odds ratio
1218 Johansen et al.
Table 1. Demographic and Other Characteristics of Participants in the Case-Control Study of Maternal Consumption of Caffeine-containing
Beverages and Oral Clefts, Norway, 1996–2001
Cleft Lip With or Without
Cleft Palate (n 5 377)
Median
(25th, 75th
percentile)a
%
Mean
(SD)
Cleft Palate Only
(n 5 196)
Median
(25th, 75th
percentile)a
%
Control Group
(n 5 763)
Mean (SD)
Median
(25th, 75th
percentile)a
%
Mean
(SD)
Mother’s characteristics
Coffee consumption before
pregnancy, cups/day
3.0 (1.0, 4.1)
3.0 (1.0, 5.0)
3.0 (1.0, 4.3)
Coffee consumption during
the first trimester, cups/day
2.0 (0.7, 4.0)
2.0 (0.4, 3.0)
2.0 (0.7, 3.0)
Coffee consumers during
the first trimester
Tea consumption during the
first trimester, cups/day
56.0
1.0 (0.4, 2.0)
Tea consumers during the
first trimester
Soft drink consumption in the
first trimester, cups/day
49.0
45.7
1.0 (0.3, 2.0)
62.1
1.0 (0.4, 2.0)
62.2
0.6 (0.3, 2.0)
71.7
0.6 (0.3, 1.0)
0.6 (0.3,1.5)
Soft drink consumers during
the first trimester
77.1
70.9
73.1
Folic acid supplement use
during the first trimester
(400 lg)
13.1
15.8
19.0
Multivitamin use during the
first trimester
32.6
36.2
36.6
Smoking during the first
trimesterb
44.1
36.8
31.9
Alcohol consumption,
drinks/sitting
2.0 (1.0, 2.0)
1.0 (1.0, 2.0)
Age at delivery, years
Height, cm
1.0 (1.0, 2.0)
28.9 (4.9)
28.9 (5.1)
29.2 (4.8)
168.6 (5.7)
166.9 (6.6)
167.7 (6.0)
Prepregnancy weight, kg
67.2 (12.9)
66.2 (13.6)
Body mass index, kg/m2
23.6 (4.3)
23.8 (4.5)
66.0 (11.3)
23.4 (3.7)
Education less than
high school
18.8
11.2
11.0
Working during the
first trimester
76.3
79.5
83.1
Father’s income <250,000
Norwegian kroner
52.6
54.5
47.3
Other birth defects
16.7
39.8
5.0
Abbreviation: SD, standard deviation.
Intake among consumers only.
b
All levels of active smoking versus nonsmoking and passive smoking.
a
of CLP increased by 7% per-cup increase in daily coffee
intake (adjusted odds ratio ¼ 1.07, 95% confidence interval
(CI): 1.00, 1.16). Compared with those for women with zero
coffee consumption, the adjusted odds ratios of CLP were
1.39 (95% CI: 1.01, 1.92) for daily coffee consumption of
less than 3 cups a day and 1.59 (95% CI: 1.05, 2.39) for
consumption of 3 or more cups a day (Table 2), and inspection of categories of coffee intake confirmed that there was
a trend in risk by dose (Ptrend ¼ 0.013 in the adjusted analyses). The association between coffee consumption and
CLP persisted among nonsmokers (among whom there
would presumably be no residual confounding by smoking)
and among mothers of isolated cleft cases (Table 2). We
found no evidence of an association between maternal coffee consumption during the first trimester and the risk of
CPO (Table 2).
Consumption of caffeine-containing tea was associated
with a decrease in the odds ratio of both CLP and CPO
(Table 2). Compared with no tea intake, daily tea intake of
3 or more cups gave adjusted odds ratios of 0.55 (95% CI:
0.32, 0.95) for CLP and 0.58 (95% CI: 0.31, 1.07) for CPO.
Soft drinks that contain caffeine were positively associated
with both types of facial clefts, although with confidence
intervals that did not exclude 1 (Table 2).
Table 3 shows maternal intake of caffeine from all beverages in relation to cleft risk. Although there was
Am J Epidemiol 2009;169:1216–1222
Am J Epidemiol 2009;169:1216–1222
Table 2. Maternal Consumption of Caffeine-containing Coffee, Tea, and Soft Drinks During the First Trimester and Odds Ratios of Cleft Lip With or Without Cleft Palate and Cleft Palate Only,
Norway, 1996–2001
Cleft Lip With or Without Cleft Palate
Crude
Analysis
(n 5 377/763)b
Coffee, per-cup increase
Cleft Palate Only
Isolateda Cases
All Cases
Adjustedc
Analysis
(n 5 318/653)
Crude
Analysis
(n 5 314/763)
Isolateda Cases
All Cases
Adjustedc
Analysis
(n 5 263/653)
Crude
Analysis
(n 5 196/763)
Adjustedc
Analysis
(n 5 178/653)
Crude
Analysis
(n 5 118/763)
Adjustedc
Analysis
(n 5 108/653)
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
1.11
1.04, 1.18
1.07
1.00, 1.16
1.09
1.00, 1.17
1.09
1.00, 1.17
1.00
0.92, 1.09
0.98
0.88, 1.09
0.95
0.84, 1.07
0.94
0.82, 1.09
Coffee, categoricald
>0–<3 cups/day
1.37
1.03, 1.81
1.39
1.01, 1.92
1.41
1.05, 1.90
1.47
1.05, 2.07
1.17
0.83, 1.66
1.26
0.85, 1.86
1.11
0.72, 1.70
1.24
0.77, 1.99
3 cups/day
1.80
1.29, 2.53
1.59
1.05, 2.39
1.85
1.29, 2.64
1.67
1.08, 2.58
1.07
0.68, 1.70
0.96
0.55, 1.67
0.88
0.48, 1.61
0.91
0.45, 1.85
P for trend
0.013
<0.001
Tea, per-cup increase
0.85
0.76, 0.94
0.86
0.76, 0.98
<0.001
1.01
0.97, 1.05
0.566
<0.001
1.01
0.97, 1.05
0.86
0.75, 0.99
0.760
0.82
0.70, 0.96
0.879
0.81
0.67, 0.98
0.877
0.79
0.64, 0.97
d
Tea, categorical
>0–<3 cups/day
0.68
0.52, 0.88
0.74
0.55, 1.01
0.65
0.49, 0.86
0.72
0.52, 0.99
0.65
0.46, 0.91
0.66
0.45, 0.95
0.64
0.43, 0.97
0.64
0.41, 1.01
3 cups/day
0.50
0.31, 0.80
0.55
0.32, 0.95
0.49
0.30, 0.82
0.53
0.30, 0.94
0.68
0.39, 1.18
0.58
0.31, 1.07
0.49
0.23, 1.05
0.45
0.20, 1.01
Soft drinks, per-cup increase
0.001
1.04
0.97, 1.11
0.014
1.05
0.96, 1.14
0.001
1.04
0.97, 1.11
0.011
1.04
0.95, 1.14
0.033
1.03
0.96, 1.12
0.025
1.05
0.95, 1.15
0.018
1.06
0.97, 1.15
0.020
1.06
0.96, 1.18
Soft drinks, categoricald
>0–<3 cups/day
1.20
0.90, 1.62
1.16
0.84, 1.62
1.23
0.90, 1.69
1.17
0.82, 1.67
0.85
0.60, 1.22
0.84
0.56, 1.24
1.15
0.72, 1.83
1.14
0.69, 1.89
3 cups/day
1.44
0.93, 2.23
1.48
0.88, 2.49
1.43
0.90, 2.27
1.44
0.82, 2.51
1.15
0.68, 1.96
1.30
0.70, 2.40
1.36
0.69, 2.67
1.43
0.65, 3.13
P for trend
0.086
0.144
0.107
0.193
0.928
0.788
0.371
0.384
Abbreviation: CI, confidence interval.
No accompanying malformations.
b
All parenthetical information is expressed as number of mothers of cases/number of mothers of controls.
c
Odds ratios were adjusted for maternal nausea, smoking, alcohol consumption, folic acid supplement use, multivitamin supplement use, coffee consumption (in the analysis of tea and soft
drinks), tea consumption (in the analysis of coffee and soft drinks), dietary folate, dietary vitamin A, work status during the first trimester, educational level, income level (father), and year of
birth.
d
Reference category: 0 cups/day.
a
Maternal Caffeine Consumption and Oral Clefts
P for trend
1219
Abbreviation: CI, confidence interval.
No accompanying malformations.
b
All parenthetical information is expressed as number of mothers of cases/number of mothers of controls.
c
Odds ratios were adjusted for maternal nausea, smoking, alcohol consumption, folic acid supplement use, multivitamin supplement use, dietary folate, dietary vitamin A, work status during
the first trimester, educational level, income level (father), and year of birth.
d
Reference category: 0–100 mg.
a
0.297
0.32, 2.11
0.83
0.40, 1.93
0.299
0.88
0.54, 2.16
0.475
1.08
0.70, 2.25
0.863
1.26
0.62, 2.02
0.851
1.12
0.96, 2.54
0.138
1.56
0.66, 2.04
0.834
1.16
0.122
1.00, 2.50
1.58
500 mg
P for trend
0.48, 1.18
0.76
0.51, 1.14
1.05
>100–<500 mg
0.81, 1.36
0.97
0.72, 1.30
1.07
0.82, 1.42
0.99
0.72, 1.36
0.82
0.59, 1.15
0.77
0.53, 1.11
0.76
0.80, 1.05
0.92
0.82, 1.04
1.08
Caffeine, per 100-mg
increased
1.02, 1.15
1.05
0.98, 1.13
1.08
1.02, 1.16
1.05
0.97, 1.14
0.98
0.90, 1.07
0.95
0.86, 1.06
0.92
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
95%
CI
Odds
Ratio
Adjustedc
Analysis
(n 5 108/653)
Crude
Analysis
(n 5 118/763)
Adjustedc
Analysis
(n 5 178/653)
Crude
Analysis
(n 5 196/763)
Adjustedc
Analysis
(n 5 262/653)
Crude
Analysis
(n 5 313/763)
Adjustedc
Analysis
(n 5 318/653)
Crude
Analysis
(n 5 375/763)b
Isolated Casesa
Cleft Palate Only
All Cases
Isolateda Cases
Cleft Lip With or Without Cleft Palate
All Cases
Table 3. Maternal Consumption of Caffeine During the First Trimester and Odds Ratios of Cleft Lip With or Without Cleft Palate and Cleft Palate Only, Norway, 1996–2001
1220 Johansen et al.
a positive association in the crude analysis, the association was reduced after adjustment. We also considered
mothers who reported drinking coffee during the year before pregnancy but not during the first trimester. There was
only a weak, positive association with risk of CLP in this
group (adjusted odds ratio ¼ 1.21, 95% CI: 0.80, 1.85)
(Table 4).
DISCUSSION
Maternal intake of coffee during the first 3 months of the
pregnancy was associated in a dose-response manner with
risk of delivering an infant with CLP. In contrast, we found
no evidence of an association between coffee intake and risk
of CPO. The association between coffee and CLP was only
slightly decreased by adjustments for confounders, and it
persisted for nonsmokers and the subset of infants with isolated CLP.
There is no known mechanism by which coffee intake
might increase the risk of CLP. Effects on homocysteine is
one potential pathway. Evidence suggests that maternal
hyperhomocysteinemia may be linked to increased risk
of CLP (13). Coffee intake increases the plasma concentration of homocysteine (14–16), as does smoking (15),
a well-established risk factor for CLP (17). Folic acid supplements are consistently associated with reduced risk of
CLP (18), and such supplements reduce plasma homocysteine (15). In the present study, the association between
high coffee intake and CLP was slightly stronger for
women who did not take a folic acid supplement (crude
odds ratio ¼ 1.99, 95% CI: 1.30, 3.04), although this interaction did not approach statistical significance (P for
interaction ¼ 0.89).
Consumption of caffeine-containing tea was strongly associated with a reduced risk of both CLP and CPO. Potential
health benefits of tea have been linked to its high content of
antioxidants (19). This is not a likely explanation for the
reduced cleft risk, however, because coffee has an even
higher total content of antioxidants than tea does (20).
The association of tea with lower risk of both types of clefts
may reflect the presence of unmeasured confounding factors. Tea drinkers may have more healthy habits; consumers
of high quantities of tea in our study were older, more educated, and drank less alcohol per sitting compared with
nonconsumers. Furthermore, the diet of consumers of high
quantities of tea contained more of every macronutrient and
almost every micronutrient compared with the diet of nonconsumers (data not shown).
The association of coffee with CLP appears to be independent of the role of caffeine. We found no association
between total caffeine intake and risk of CLP (reflecting
the combination of the positive association with coffee and
the negative association with tea). Only 5 women drank
decaffeinated coffee exclusively, too few for a separate
analysis. When we combined data on decaffeinated coffee
with those on caffeinated coffee, the odds ratios for CLP
were slightly increased, consistent with the association
of coffee and CLP being unrelated to caffeine intake (data
not shown).
Am J Epidemiol 2009;169:1216–1222
Maternal Caffeine Consumption and Oral Clefts
1221
Table 4. Maternal Coffee Consumption Before and During Pregnancy and Odds Ratios of Cleft Lip With or Without Cleft Palate, Norway, 1996–
2001
Crude Odds Ratio
95% CI
Adjusteda Odds Ratio
95% CI
Quitters (cases/controls ¼ 57/135): consumed coffee the year
before pregnancy but not during the first trimester
1.06
0.72, 1.54
1.21
0.80, 1.85
Stable consumers (cases/controls ¼ 208/348): consumed coffee
both the year before pregnancy and during the first trimester
1.49
1.13, 1.97
1.53
1.10, 2.12
Stable high consumers (cases/controls ¼ 78/110): consumed 3 cups
of coffee/day both the year before pregnancy and during the first trimester
1.77
1.23, 2.55
1.61
1.04, 2.49
b
Never consumers (cases/controls ¼ 112/280 ): did not consume
coffee before pregnancy or during the first trimesterc
Abbreviation: CI, confidence interval.
Adjusted for maternal nausea, smoking, alcohol consumption, folic acid supplement use, multivitamin supplement use, dietary folate, dietary
vitamin A, tea consumption, work status during the first trimester, educational level, income level (father), and year of birth.
b
All parenthetical information is expressed as number of mothers of cases/number of mothers of controls.
c
Reference category.
a
By the same token, high-quantity coffee consumers (>3
cups/day) were older, less educated, smoked more, and
drank more alcohol per sitting compared with nonconsumers. Even though we adjusted for possible confounding
factors, we cannot rule out the possibility of residual confounding by known factors such as smoking or confounding
by unmeasured factors. Although we did not control for diet,
there was no evidence of a poorer diet among consumers of
high quantities of coffee, who actually reported eating more
vegetables, less sugar, and more of many essential nutrients
(data not shown).
Another potential source of bias in this study comes from
possible selective participation of controls. While participation was relatively high (88% for cases and 76% for controls), the lower participation of controls leaves room for
differential participation by coffee drinking. However, it is
unlikely that such selection would occur for one type of
facial cleft and not the other. Coffee was strongly associated
with CLP but not with CPO in our data. This specificity has
been found for other factors associated with facial clefts (6).
By the same argument, the lack of specificity for the tea
association (which was protective for both types of facial
clefts) raises the question of whether this association might
be due to some unmeasured bias.
Women may reduce their coffee consumption as they develop pregnancy symptoms of nausea and vomiting. Given
that closure of the lip and palate occurs relatively late in the
first trimester (8–12 weeks after the last menstrual period)
(1), it is possible that reported coffee intake is greater than
actual consumption at the crucial stage of embryonic development. This bias would tend to weaken the observed
association.
Our study had the advantage of enrolling mothers soon
(an average of 15 weeks) after delivery. In addition, questions on coffee and other caffeinated beverages constituted
only a small part of the questionnaire, with no specific emphasis on these beverages that would be expected to bias
reporting. Another strength of the study was collection of
extensive data on potential confounders such as folic acid
supplement use, alcohol consumption, and smoking. Confounders were adjusted for as continuous variables in our
Am J Epidemiol 2009;169:1216–1222
analyses, but adjustment using categorized variables did not
alter the results.
A meta-analysis of 3 studies on maternal coffee consumption and orofacial clefts found a slight increase in the risk of
clefts (11). All 3 studies used 0 cups as the reference category. When high coffee intake was compared with low intake, the pooled odds ratio was 1.2 (95% CI: 0.9, 1.6). One
of the studies provided results for CLP separately, with an
adjusted odds ratio for CLP of 1.3 (95% CI: 0.9, 1.9) associated with more than 3 cups of coffee a day (11). The 2
other studies combined both types of clefts in their analyses.
In the report by Kurppa et al. (21), drinking more than 4
cups of coffee a day had no association with risk of clefts
(unadjusted odds ratio ¼ 1.0, 95% CI: 0.6, 1.6), whereas,
according to McDonald et al. (22), more than 3 cups of
coffee daily resulted in an adjusted odds ratio of 1.4 (95%
CI: 0.7, 2.7).
A recent cohort study from Denmark found that coffee
intake was associated with a reduced risk of CLP (23). The
authors observed an odds ratio of 0.66 (95% CI: 0.27, 1.62)
when comparing daily intake of more than 5 cups of coffee
with no intake. The Danish study had the advantage of a prospective design, although one cost of this design was a relatively small number of cases (134 with CLP).
In summary, results from our study showed a dosedependent association between coffee consumption during
the first trimester and increased risk of CLP. This association
was specific to CLP, with no association found between
coffee consumption and risk of CPO. There was little or
no evidence for an association between caffeine from other
types of beverages and CLP. Even with extensive adjustments for confounders, we cannot eliminate the possibility
that the associations between coffee consumption and risk
of CLP are due to uncontrolled confounding by factors associated with the habit of drinking coffee. Still, considering
our results and the prior mixed evidence for a coffee effect
on clefts, women cannot be assured that maternal coffee
consumption is entirely benign for the developing fetus.
Other clefts studies now in progress should give close attention to a possible association of coffee consumption with
facial clefts.
1222 Johansen et al.
ACKNOWLEDGMENTS
Author affiliations: Department of Nutrition, Institute of
Basic Medical Sciences, Faculty of Medicine, University of
Oslo, Oslo, Norway (Anne Marte W. Johansen, Lene F.
Andersen, Christian A. Drevon); Epidemiology Branch,
National Institute of Environmental Health Sciences/National
Institutes of Health, Durham, North Carolina (Allen J.
Wilcox); Section for Epidemiology and Medical Statistics,
Department of Public Health and Primary Health Care,
University of Bergen, Bergen, Norway (Rolv T. Lie); and
Medical Birth Registry of Norway, Norwegian Institute of
Public Health, Bergen, Norway (Rolv T. Lie).
This work was supported by the Research Council of
Norway (grant 166026/V50); the Freia Medical Foundation; the Throne-Holst Foundation for Nutrition Research;
the thematic area of perinatal nutrition, Faculty of Medicine, University of Oslo, Oslo, Norway; and Nutrigenomics, Network of Excellence, FP6, Food Quality and Safety
(NuGO FP6-506360). This research was supported in part
by the Intramural Research Program of the National Institutes of Health, National Institute of Environmental Health
Sciences.
Conflict of interest: none declared.
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