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Comparison of binge drinking among pregnant and nonpregnant women, United States, 1991-1995
American Journal of Obstetrics and Gynecology Founded in 1920 volume 180 number 1 part 1 JANUARY 1999
PRIMARY CARE
Comparison of binge drinking among pregnant and nonpregnant women, United States, 1991-1995 Shahul H. Ebrahim, MD, MSc, DrMed, Shane T. Diekman, MPH, R. Louise Floyd, RN, DSN, and Pierre Decoufle, ScD Atlanta, Georgia Our goal was to measure the pregnancy-related reduction in the prevalence of reported binge drinking (≥5 alcoholic drinks per occasion) and to characterize binge drinkers among pregnant and nonpregnant women aged 18-44 years, in the United States, 1991-1995. We used the Behavioral Risk Factor Surveillance System data from 46 states. We used the prevalence rate ratio between pregnant and nonpregnant women to determine the magnitude of the reduction in reported binge drinking and multiple logistic regression models to identify characteristics associated with binge drinking. Between 1991 and 1995, the prevalence of binge drinking among pregnant women increased significantly from 0.7% (95% confidence interval 0.2-0.9) to 2.9% (95% confidence interval 2.2-3.6), whereas among nonpregnant women the prevalence changed little (11.3% vs 11.2%). Over the study period pregnant women were one fifth (prevalence rate ratio 0.2, 95% confidence interval 0.1-0.2) as likely as nonpregnant women to binge drink. Among various population subgroups of women, pregnancy-related reduction in binge drinking was smallest among black women and largest among women aged ≤30 years and among those who had quit smoking. Among pregnant women binge drinking was independently associated with being unmarried, being employed, and current smoking. Among nonpregnant women binge drinking was independently associated with age ≤30 years, nonblack race, college level education, being unmarried, being employed or a student, and current smoking. Clinicians serving women of childbearing age need to be aware of the recent rise in reported binge drinking during pregnancy, as well as the known risk factors for binge drinking. (Am J Obstet Gynecol 1999;180:1-7.)
Key words: Pregnancy, alcohol, binge drinking, United States
Binge drinking, generally defined as the episodic intake of large quantities of alcohol, has been increasingly recognized as harmful to the developing fetus.1-7 However, the association between binge drinking and adverse pregnancy outcomes in humans remains inconclusive. Some morphologic abnormalities characteristic of children with fetal alcohol syndrome have been predominantly associated with a binge drinking pattern,2
From the Division of Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention. Presented in part at the One Hundred Twenty-fifth Annual Meeting of the American Public Health Association, Indianapolis, Indiana, November 12, 1997. Reprint requests: Shahul H Ebrahim, MD, MSc, DrMed, FAS Prevention Section, CDC, Mail Stop F15, 4770 Buford Highway NE, Atlanta, GA 30341-3724. 6/1/94475
whereas other alcohol-related birth defects have been seen with increased frequency among children of moderate drinkers who also binge drink while pregnant.6 Findings of recognizable physical abnormalities attributable to binge drinking may have been partially obscured by variations in the definitions of alcohol exposure necessary for a classification of “binge drinking” in various studies. However, a consistent finding is that a single or intermittent gestational exposure resulting in high peak blood alcohol concentrations produces observable behavioral and cognitive teratogenic effects.1, 3, 7 Unlike chronic alcoholism, binge drinking appears to be a more socially acceptable behavior in many circumstances.8-10 The opportunities for unknowingly exposing a fetus to alcohol early in the first trimester may be great because more than half of US pregnancies are unintended,11 and many women are not aware of the fact that they are 1
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Fig 1. Prevalence of binge drinking among US women aged 18-44 years by pregnancy status, 1991-1995 (1994 was excluded from the analysis because alcohol data were not collected in most states that year).
pregnant until 6-8 weeks of gestation. An additional concern is that women who binge drink may increase their risk of unplanned pregnancy8-10 and therefore be more likely to expose a fetus to high peak blood alcohol concentrations. Although there are population estimates of alcohol consumption patterns during pregnancy, including frequent or heavy alcohol consumption, there is relatively little information available on the extent of perinatal binge drinking nationally. A recent review of reproductive health risks related to binge drinking during pregnancy pointed out a number of methodologic problems that have contributed to this lack of information.1 For example, most studies tend to establish the usual pattern, frequency, and amount of alcohol intake and neglect to ascertain high-level intake on infrequent occasions. Because fetal alcohol syndrome is associated with chronic drinking during pregnancy, even if information about binge drinking is available, it is often subsumed within an overall category of frequent or heavy alcohol use. Recent reports on alcohol drinking among pregnant women showed that most women included in the category of frequent drinkers are also binge drinkers.12 In addition, point prevalence estimates of binge drinking among pregnant women were 4 times higher in 1995 than in 1991.12 In this article we compare US rates of binge drinking among pregnant women with those among nonpregnant women of childbearing age for the years 1991-1995. We also examine the characteristics associated with binge drinking among pregnant and nonpregnant women. We based our analysis on cross-sectional data from 46 states. Material and methods Data for this analysis are from the Behavioral Risk Factor Surveillance System (BRFSS).13 The BRFSS, sponsored by the Centers for Disease Control and Prevention (CDC), is a state-based ongoing surveillance of modifiable risk factors
for chronic diseases and other leading causes of morbidity and mortality. The BRFSS is a telephone survey of the noninstitutionalized civilian population aged ≥18 years. The median response rate (ratio of completed interviews to the sum of completed interviews and refusals) across the 4-year study period ranged from 80% to 85%. Information on alcohol use was collected each year from 1991-1995, except in 1994. In 1991 and 1992 respondents were asked the following question about alcohol use: “Have you had any beer, wine, or liquor during the past month?” In 1993 and 1995 this question was reworded to the following: “During the past month, have you had at least one drink of any alcoholic beverage such as beer, wine, wine coolers, or liquor?” Respondents who answered yes to the opening question in 1991 and 1992 were then asked the following question on binge drinking: “Considering all types of alcoholic beverages, that is, beer, wine, and liquor as drinks, how many times during the past month did you have 5 or more drinks on an occasion?” For 1993 and 1995 the question on binge drinking was simplified to exclude the listing of examples of alcoholic beverages. The question on pregnancy status (“To your knowledge, are you now pregnant?”) was asked in the latter part of the interview, after the questions on alcohol use. For this analysis binge drinking was defined as a positive response to both of the above-mentioned questions on alcohol use. This analysis was restricted to women aged 18 to 44 years, who lived in one of the 46 states that collected alcohol use information consistently during all years of the study period. For this analysis we weighted the state-specific data to reflect the general population of all 46 states. Of a total of 113,795 women who completed interviews during this period, we excluded 9872 for whom information on pregnancy status was missing or who were unsure of their pregnancy status. Thus the final analysis included 103,923 women, of whom 4611 were pregnant
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(weighted percentage 5). The percentage of women who were pregnant changed little over the study years. The distribution of pregnant women by selected demographic characteristics was comparable with that of nonpregnant women, except for age, marital status, and employment status (Table I). Pregnant women were younger and more likely to be married than nonpregnant women. Consistent with national estimates,14 women aged ≤30 years accounted for about 70% of all pregnancies. We obtained the percentage of women who consumed any amount of alcohol in the month before the survey by pregnancy status. We obtained the percentage of women who binged among pregnant and nonpregnant women by calendar year and also by selected sociodemographic variables. Because there is a legal restriction on sale of alcohol products to persons <21 years old,15 we used 20 as the upper limit for the youngest age group. Because of the small sample size for pregnant women, we did not compare prevalence rates for sociodemographic subgroups by year. To assess the magnitude of the pregnancy-related reduction in binge drinking, we computed prevalence rate ratios for binge drinking by dividing the prevalence among pregnant women by the prevalence among nonpregnant women for each of the various sociodemographic subgroups. The prevalence rate ratio provides a proxy measure of pregnancy-related changes in the prevalence of binge drinking. Using the prevalence rate ratio we identified subgroups of women that showed the least and greatest pregnancy-related decreases in binge drinking rates. Higher prevalence rate ratios indicate a lower pregnancy-related reduction in binge drinking, and lower values indicate a higher pregnancy-related reduction in binge drinking. To determine how prevalent binge drinking is as a pattern of alcohol use among alcohol drinkers, we did a subanalysis of those women who reported consumption of any amount of alcohol by pregnancy status. To identify sociodemographic characteristics of women associated with greater risk of binge drinking, we used multiple logistic regression models separately for pregnant and nonpregnant women and computed odds ratios and their 95% confidence intervals. The independent variables were age, race, education, marital status, employment, household income, and tobacco smoking. We used SUDAAN for all statistical analyses.16 Because we chose to round off all results to 1 decimal place and because of the large sample size, some point estimates appear to be the same as their upper or lower confidence limits. A value of P < .05 was considered statistically significant. Results During the study period, 641 (13.7%) pregnant women and 52,654 (52.8%) nonpregnant women reported drinking alcohol in the month before the survey. Further, 93 (weighted percentage 1.9) pregnant women and 11,165 (weighted percentage 11.6) nonpregnant women re-
Table I. Demographics of women in BRFSS, 1991-1995*
Characteristic Age 18-20 y 21-30 y 31-44 y Race White Black Other Education ≤11 y High school College level Marital status Married Other Employment status Employed Student Other Annual household income <$20,000 $20,000-$50,000 >$50,000
Pregnant (n = 4611) (%†)
Nonpregnant (n = 99,312) (%†)
13.1 56.2 30.7
10.1 38.1 51.8
72.6 10.5 16.9
74.6 10.9 14.5
11.8 34.2 54.0
9.4 33.1 57.5
77.1 22.9
56.0 44.0
55.6 4.6 39.8
66.8 8.9 24.3
31.0 47.8 21.2
30.1 48.2 21.7
*1994 was excluded from the analysis because alcohol data were not collected in most states that year. †Percentages are weighted.
ported binge drinking. In the total sample of pregnant women 1.1% (or 57% of the 93 binge drinkers) binged ≥2 times and 0.5% binged ≥3 times in the month before the survey. In the total sample of nonpregnant women 5.9% (or 50% of the 11,165 binge drinkers) binged ≥2 times and 3.4% binged ≥3 times in the month before the survey. Time trends. In the total sample, among pregnant women the prevalence of binge drinking increased significantly from 0.7% (95% confidence interval 0.3-0.9) in 1991 to 2.9% (95% confidence interval 2.2-3.6) in 1995 but changed little among nonpregnant women (Fig 1). Among nonpregnant women the prevalence of binge drinking did not vary significantly over time in any of the sociodemographic subgroups studied (data not shown). Within the subset of 641 pregnant women who were alcohol drinkers, binge drinking as a pattern of drinking increased from 5.4% (95% confidence interval 4.1-6.3) in 1991 to 18.3% (95% confidence interval 17.2-19.6) in 1995. Within the subset of 52,654 nonpregnant women who were alcohol drinkers, binge drinking as a pattern of drinking varied little over time (range 21.0%-23.1%). Pregnancy-related reduction in binge drinking. Overall, pregnant women were about one fifth (prevalence rate ratio 0.2, 95% confidence interval 0.1-0.2) as likely to binge drink as nonpregnant women (Table II). However, the pregnancy-related reduction in binge drinking rates varied substantially by sociodemographic subgroups (Table II). Pregnancy-related reduction in the prevalence of binge drinking was least among black women
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Table II. Prevalence rates and prevalence rate ratios of binge drinking among pregnant and nonpregnant women, United States, 1991-1995* Weighted percentage Characteristic TOTAL
Age 18-20 y 21-30 y 31-44 y Statistical significance Race White Black Other Statistical significance Education ≤11 y High school College level Statistical significance Marital status Married Other Statistical significance Employment status Employed Student Other Statistical significance Annual household income <$20,000 $20,000-$50,000 >$50,000 Statistical significance Tobacco smoking Never Past Current Statistical significance
Pregnant
Nonpregnant
Prevalence rate ratio
95% Confidence interval
1.9
11.6
0.2
0.1-0.2
2.1 1.6 2.2 P = .56
15.6 15.8 7.8 P < .01
0.1 0.1 0.3
0.1-0.3 0.1-0.3 0.2-0.4
1.7 3.4 1.8 P = .33
13.2 5.7 8.3 P < .01
0.1 0.6 0.2
0.1-0.2 0.4-1.0 0.1-0.4
1.1 2.2 1.9 P = .23
10.7 11.5 11.9 P = .07
0.1 0.2 0.2
0.1-0.2 0.1-0.3 0.1-0.2
1.2 4.2 P < .01
7.5 17.0 P < .01
0.2 0.3
0.1-0.2 0.2-0.3
2.5 1.9 1.1 P = .03
12.1 17.3 8.4 P < .01
0.2 0.1 0.1
0.2-0.3 0.1-0.2 0.1-0.2
1.8 1.8 2.8 P = .60
13.7 11.5 10.9 P < .01
0.1 0.2 0.3
0.1-0.2 0.1-0.2 0.2-0.4
1.2 1.2 5.5 P < .01
7.4 12.9 21.2 P < .01
0.2 0.1 0.3
0.1-0.2 0.1-0.2 0.2-0.4
χ2 tests for homogeneity among subgroups were conducted separately for pregnant and nonpregnant women, and the results are indicated as P values below percentages for each category. Also, because of rounding, some point estimates appear to be the same as their confidence limits. *1994 was excluded from the analysis because alcohol data were not collected in most states that year. †Prevalence among pregnant women/Prevalence among nonpregnant women.
(prevalence rate ratio 0.6, 95% confidence interval 0.41.0) and was somewhat less than average among women aged ≥31 years and among current tobacco smokers. The largest pregnancy-related reduction in binge drinking (indicated by a low prevalence rate ratio) was among women aged ≤30 years and women who had quit smoking. Within the subset of women who were alcohol drinkers, pregnant women were nearly two thirds as likely as nonpregnant women to binge drink (13.8% of 641 vs 22.1% of 52,654, prevalence rate ratio 0.6, 95% confidence interval 0.3-0.9). Characteristics. Despite alcohol purchase and consumption being illegal for people <21 years old, the prevalence of binge drinking among pregnant women <21 years old was comparable to that among pregnant women in the other age groups (P = .56). However,
among nonpregnant women <21 years old the prevalence of binge drinking was significantly higher than that among nonpregnant women aged 31-44 years (Table II). Subgroups of pregnant and nonpregnant women at increased risk for binge drinking were similar in the univariate analysis and in the multivariate logistic regression model (Tables II and III). For pregnant women the subgroups were unmarried, employed, or current smokers. For nonpregnant women the subgroups were age ≤30 years, nonblack race, unmarried, employed, student, or current-prior tobacco smoker, except for annual household income of ≤$20,000, which was only significant in the univariate analysis. Prior tobacco smoking was associated with binge drinking only among nonpregnant women (odds ratio 1.9, 95% confidence interval 1.8-2.0), whereas current tobacco smoking was associated with
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Table III. Multiple logistic regression estimates* of odds ratios for binge drinking among subgroups of pregnant and nonpregnant women, 1991-1995† Pregnant
Characteristic Age 18-20 y 21-30 y 31-44 y Race White Black Other Education ≤11 y High school College level Marital status Married Other Employment status Employed Student Other Annual household income <$20,000 $20,000-$50,000 >$50,000 Tobacco smoking Never Past Current
Nonpregnant
95% Confidence interval
Odds ratio
0.7 1.0 1.2
0.3-1.5 Referent 0.7-1.9
1.6 1.9 1.0
1.5-1.8 1.8-2.0 Referent
1.0 1.1 1.2
Referent 0.6-2.2 0.7-2.3
2.5 1.0 2.0
2.3-2.7 Referent 1.8-2.2
1.0 0.7 0.9
Referent 0.2-3.2 0.2-4.0
1.0 1.2 1.2
Referent 1.0-1.4 1.1-1.5
1.0 4.2
Referent 2.6-7.0
1.0 2.1
Referent 2.0-2.2
2.1 2.2 1.0
1.3-3.6 0.9-5.8 Referent
1.4 1.5 1.0
1.3-1.4 1.4-1.7 Referent
1.0 1.2 1.3
Referent 0.7-2.0 0.6-2.7
1.0 1.0 1.0
1.0-1.1 1.0-1.1 Referent
1.0 1.1 3.5
Referent 0.6-2.1 2.1-5.7
1.0 1.9 3.2
Referent 1.8-2.0 3.1-3.3
Odds ratio
95% Confidence interval
Reference groups were chosen as the subgroups of women with the smallest prevalence rates (as shown in Table II) and were different for pregnant and nonpregnant women. Because of rounding, some point estimates appear to be the same as their confidence intervals. *Adjusted for age, race, education, marital status, employment status, annual household income, and tobacco smoking. †1994 was excluded from the analysis because alcohol data were not collected in most states that year.
binge drinking among both pregnant (odds ratio 3.5, 95% confidence interval 2.1-5.7) and nonpregnant (odds ratio 3.2, 95% confidence interval 3.1-3.3) women. Comment To our knowledge this is the first study of binge drinking by pregnant women in the United States that has used a representative national sample. In this sample of women aged 18-44 years we found that pregnant women were one fifth as likely as nonpregnant women to binge drink. At least half of pregnant and nonpregnant binge drinkers reported binge drinking on ≥2 occasions in the month before the survey. This analysis also documents an overall increase from 1991 through 1995 in reported binge drinking among pregnant women that was not found among nonpregnant women. Direct comparison of prevalence rates of binge drinking found in the BRFSS with those found in other surveys on alcohol use is difficult because of variations in survey design and the absence of information on pregnancy in many surveys. The National Household Survey on Drug Abuse (NHSDA) collected pregnancy data from women
aged 15 to 44 years in 1994 and 1995.17 In that survey the prevalence of binge drinking for 1994 and 1995 combined was similar to that found in our study for 1995 among pregnant women (2.9% vs 2.9%) but slightly higher among nonpregnant women (15.8% vs 11.6%).17 The NHSDA’s higher prevalence of binge drinking among nonpregnant women may be because the NHSDA oversampled some subgroups of women and had a wider age range (15-44 years) than our survey population (18-44 years). The recent increase that we found in binge drinking by pregnant women reflects the increases in consumption of any amount of alcohol reported among women in the NHSDA17 and among pregnant women in the BRFSS.12 The NHSDA showed a slight increase in any alcohol consumption, from 41.4% in 1992 to 45.0% by 1995 among US women aged ≥12 years.17 The disproportionate increases in reported binge drinking among pregnant alcohol users suggests that binge drinking is becoming a more popular pattern of alcohol use among pregnant women. Previously suggested explanations for these recent increases in binge drinking include increasing recent reports on the health benefits of moder-
6 Ebrahim et al
ate alcohol drinking and a relative increase in alcohol promotion efforts compared with public health interventions to reduce drinking.18 Although 90% of women are aware that alcohol use during pregnancy can damage the fetus,19 it is not known whether women believe that binge drinking carries as much risk as frequent or daily drinking. The rephrasing of the alcohol questions from 1993 on may have affected the reported rates of binge drinking: The opening question on drinking in the 1993 survey was more specific than that on the earlier surveys, which could have led to an increase in the percentage of women who reported drinking. On the other hand, the rephrasing of questions on binge drinking in 1993, which excluded examples of alcoholic beverages, could actually have led to a decrease in the percentage of women who reported binge drinking and not an increase. Because the rephrasing of the alcohol questions did not affect the rates in alcohol use among nonpregnant women in a magnitude similar to that in pregnant women, further studies are needed to determine whether pregnant and nonpregnant women respond differently to rephrasing of alcohol questions. An important strength of this study is that the question on pregnancy was asked well after questions on alcohol use had been asked. Most women know that alcohol adversely affects pregnancy, 19 and such knowledge may lead women to deny alcohol use if the alcohol questions were asked after the question on pregnancy. The known self-report bias in relation to alcohol use20 is reported to be largely limited to very heavy alcohol users21 and may not affect the reporting of occasional consumption of alcohol, which may be considered socially desirable.8-10 In this survey alcohol use histories were only obtained for the preceding month, leading us to classify women who drank alcohol earlier than that month as nondrinkers. In addition, the duration of time for each binge drinking “occasion” was not specified. Despite these limitations, given that the vast majority of states were included in this survey, these data provide the best available estimate of the extent of binge drinking in relation to pregnancy in the United States. People <21 years old have been found to have equal access to alcohol when compared with other age groups, despite legal restrictions on the sale of alcohol to minors.15 This high rate of alcohol exposure among minors complicates efforts to reduce alcohol-exposed pregnancies, because young women have the highest rates of unintended pregnancies (teenagers 82%, women aged 2024 years 61%)11 and are thus more likely to unknowingly expose the fetus to high levels of alcohol. Of relevance also is the fact that binge drinking is associated with other factors such as unsafe sex, sexually transmitted infections, and physical injuries that place women who binge at increased risk for adverse reproductive, pregnancy, and other poor health outcomes.22 The finding that black women had the lowest preg-
January 1999 Am J Obstet Gynecol
nancy-associated reduction in binge drinking (the prevalence rate ratio was 0.6 in black women vs 0.2 in the overall sample) is of concern and has not been previously shown. This finding on binge drinking contrasts with the finding that pregnancy-associated reduction in smoking was greatest among black women.23 Although the prevalence of any alcohol consumption was reported to be significantly higher among white women than among black women, such a difference was not reported for heavy drinking.24 Thus among the relatively few black women who drink there may be a heavier concentration of problem drinkers than among white women. Problem drinkers are also less likely to perceive drinking during pregnancy as a risk for adverse outcomes25 and are therefore less likely to reduce alcohol consumption while pregnant. Most of the other subgroups of women whose pregnancy-related reduction in binge drinking was smaller than that in the overall sample were also found to be at higher risk for binge drinking in the multiple logistic regression analysis. The characteristics of pregnant women that were associated with a high prevalence of binge drinking—unmarried, employed, and current smoking—were also found in our previous analysis of the BRFSS and by other reports on frequent drinking.18, 24 We did not find as high a prevalence of binge drinking among pregnant women who are young or who are students as have other researchers,9, 10 possibly because young women and students who are pregnant are underrepresented in the BRFSS. However, our findings did agree with earlier reports that younger age and being a student were associated with a higher prevalence of binge drinking among nonpregnant women. The prevalence of binge drinking among women who were young (15.7%) or students (17.2%) in the BRFSS was less than half the prevalence reported in a national survey on alcohol use among students on 140 campuses (39%).10 In that survey,10 however, binge drinking was defined as consumption of ≥4 drinks per occasion during the 2 weeks before the survey, whereas in the BRFSS binge drinking was defined as consumption of ≥5 drinks in the month before the survey. In addition, the low prevalence of binge drinking in the BRFSS, including among young women and students, may be the result of the exclusion of persons <18 years old, persons without telephones, and persons not living in private residences, such as those living in college dormitories. The recent increases in reported rates of binge drinking among pregnant women highlight the need for measures to sensitize women about the dangers of binge drinking during pregnancy. Efforts to reduce alcohol consumption among teenagers and young women may benefit from concerted programs focusing on family planning and the prevention of polydrug use and sexually transmitted diseases. Studies on the attitudes and practices of providers of preconcep-
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tion and prenatal care regarding binge drinking during pregnancy are clearly needed, as are studies on knowledge and attitudes of women of childbearing age concerning the effects of binge drinking on pregnancy outcomes. Individual providers of prenatal and periconceptional care can play important roles in counseling women who are likely to binge on the adverse effects of binge drinking on pregnancy. Public health agencies should increase their efforts to educate women of reproductive age about the general adverse health effects of this drinking pattern, as well as the risk it poses to any child they may conceive. We acknowledge the state coordinators of the Behavioral Risk Factor Surveillance System and the Behavioral Risk Factor Surveillance Branch of the National Center for Chronic Disease Prevention, CDC, without whose help the data would not have been available. We are indebted to Elizabeth Luman and Mike Tully for programming support. We also thank Gregg Leeman for conducting a literature search and Dr Coleen Boyle and Ms Kim Van Naarden for reviewing the manuscript. REFERENCES
1. Gladstone J, Nulman I, Koren G. Reproductive risks of binge drinking during pregnancy [review]. Reprod Toxicol 1996;10:3-13. 2. Olsen J, Tuntiseranee P. Is moderate alcohol intake in pregnancy associated with craniofacial features related to fetal alcohol syndrome? Scand J Soc Med 1995;23:156-61. 3. Olson HC, Streissguth AP, Sampson PD, Barr HM, Bookstein FL, Thiede K. Association of prenatal alcohol exposure with behavioral and learning problems in adolescence. J Am Acad Child Adolesc Psychiatry 1997;36:1187-94. 4. Streissguth AP, Barr HM, Olson HC, Sampson PD, Bookstein FL, Burgess DM. Drinking during pregnancy decreases word attack and arithmetic scores on standardized tests: adolescent data from a population-based prospective study. Alcohol Clin Exp Res 1994; 18:248-54. 5. Streissguth AP, Barr HM, Sampson PD. Moderate prenatal alcohol exposure: effects on child IQ and learning problems at age 71⁄2 years. Alcohol Clin Exp Res 1990;14:662-9. 6. Passaro KT, Little RE, Savitz DA, Noss J, the ALSPAC Study Team. The effect of maternal drinking before conception and in early pregnancy on infant birthweight. Epidemiology 1996;7:377-83. 7. Ioffe S, Chernick V. Prediction of subsequent motor and mental retardation in newborn infants exposed to alcohol in utero by computerized EEG analysis. Neuropediatrics 1990;21:11-27.
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8. Nezlek JB, Pilkington CJ, Bilbro KG. Moderation in excess: binge drinking and social interaction among college students. J Stud Alcohol 1994;55:342-51. 9. Wechsler H, Isaac NE. Binge drinkers at Massachusetts colleges: prevalence, drinking style, time trends, and associated problems. JAMA 1992;267:2929-31. 10. Wechsler H, Davenport A, Dowdall A, Dowdall G, Moeykevis B, Cartillo S. Health and behavioral consequences of binge drinking in college: a national survey of students at 140 campuses. JAMA 1994;272:1672-7. 11. Forrest DJ. Epidemiology of unintended pregnancy and contraception use. Am J Obstet Gynecol 1994;170:1485-9. 12. Centers for Disease Control and Prevention. Alcohol consumption among pregnant and childbearing aged women—United States, 1991 and 1995. MMWR Morb Mortal Wkly Rep 1997;46:346-50. 13. Remington PL, Smith MY, Williamson DF, Anda RF, Gentry EM, Hogelin GC. Design, characteristics, and usefulness of statebased behavioral risk factor surveillance: 1981-1986. Public Health Rep 1988;103:366-75. 14. Ventura SJ, Taffel SM, Mosher WD, Wilson JB, Henshaw S. Trends in pregnancies and pregnancy rates: estimates for the United States, 1980-92. Mon Vital Stat Rep 1995;43 Suppl:11. 15. Toomey TL, Rosenfeld C, Wagenaor AC. The minimum legal drinking age: history, effectiveness, and ongoing debate. Alcohol Health Res World 1996;20:213-8. 16. Shah BV. SUDAAN version 5.5 (software documentation). Research Triangle Park (NC): Research Triangle Institute; 1991. 17. Preliminary tables, 1995. In: National Household Survey on Drug Abuse. Rockville (MD): Office of Applied Studies, Substance Abuse and Mental Health Services Association; 1996. 18. Ebrahim SH, Luman ET, Floyd RI, Murphy CC, Bennett EM, Boyle CA. Alcohol consumption by pregnant women in the United States during 1988-1995. Obstet Gynecol 1998;92:187-92. 19. Dufour MC, Williams GD, Campbell KE, Aitken SS. Knowledge of FAS and the risks of heavy drinking during pregnancy, 1985 and 1990. Alcohol Health Res World 1994;18:86-92. 20. Ernhrdt CB, Morrow-Tlucak M, Sokol R J, Martier S. Under reporting of alcohol use in pregnancy. Alcohol Clin Exp Res 1988;12:506-11. 21. Roam R. Survey vs. sales data for the US. Drink Drug Pract Surv 1971;3:15-6. 22. Grodstein F, Goldman MB, Cramer DW. Infertility in women and moderate alcohol use. Am J Public Health 1994;84:1429-32. 23. Williamson DF, Serdula MK, Kendrick JS, Binkin NJ. Comparing the prevalence of smoking in pregnant and non pregnant women, 1985 to 1986. JAMA 1989;261:70-4. 24. Day NL, Cadra CM, Richardson A. Epidemiology of alcohol, marijuana, and cocaine use among women of childbearing age and pregnant women. Clin Obstet Gynecol 1993;36:237-45. 25. Testa M, Reifman A. Individual differences in perceived riskiness of drinking in pregnancy: antecedents and consequences. J Stud Alcohol 1996;57:360-7.
PRIMARY CARE
Comparison of binge drinking among pregnant and nonpregnant women, United States, 1991-1995 Shahul H. Ebrahim, MD, MSc, DrMed, Shane T. Diekman, MPH, R. Louise Floyd, RN, DSN, and Pierre Decoufle, ScD Atlanta, Georgia Our goal was to measure the pregnancy-related reduction in the prevalence of reported binge drinking (≥5 alcoholic drinks per occasion) and to characterize binge drinkers among pregnant and nonpregnant women aged 18-44 years, in the United States, 1991-1995. We used the Behavioral Risk Factor Surveillance System data from 46 states. We used the prevalence rate ratio between pregnant and nonpregnant women to determine the magnitude of the reduction in reported binge drinking and multiple logistic regression models to identify characteristics associated with binge drinking. Between 1991 and 1995, the prevalence of binge drinking among pregnant women increased significantly from 0.7% (95% confidence interval 0.2-0.9) to 2.9% (95% confidence interval 2.2-3.6), whereas among nonpregnant women the prevalence changed little (11.3% vs 11.2%). Over the study period pregnant women were one fifth (prevalence rate ratio 0.2, 95% confidence interval 0.1-0.2) as likely as nonpregnant women to binge drink. Among various population subgroups of women, pregnancy-related reduction in binge drinking was smallest among black women and largest among women aged ≤30 years and among those who had quit smoking. Among pregnant women binge drinking was independently associated with being unmarried, being employed, and current smoking. Among nonpregnant women binge drinking was independently associated with age ≤30 years, nonblack race, college level education, being unmarried, being employed or a student, and current smoking. Clinicians serving women of childbearing age need to be aware of the recent rise in reported binge drinking during pregnancy, as well as the known risk factors for binge drinking. (Am J Obstet Gynecol 1999;180:1-7.)
Key words: Pregnancy, alcohol, binge drinking, United States
Binge drinking, generally defined as the episodic intake of large quantities of alcohol, has been increasingly recognized as harmful to the developing fetus.1-7 However, the association between binge drinking and adverse pregnancy outcomes in humans remains inconclusive. Some morphologic abnormalities characteristic of children with fetal alcohol syndrome have been predominantly associated with a binge drinking pattern,2
From the Division of Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention. Presented in part at the One Hundred Twenty-fifth Annual Meeting of the American Public Health Association, Indianapolis, Indiana, November 12, 1997. Reprint requests: Shahul H Ebrahim, MD, MSc, DrMed, FAS Prevention Section, CDC, Mail Stop F15, 4770 Buford Highway NE, Atlanta, GA 30341-3724. 6/1/94475
whereas other alcohol-related birth defects have been seen with increased frequency among children of moderate drinkers who also binge drink while pregnant.6 Findings of recognizable physical abnormalities attributable to binge drinking may have been partially obscured by variations in the definitions of alcohol exposure necessary for a classification of “binge drinking” in various studies. However, a consistent finding is that a single or intermittent gestational exposure resulting in high peak blood alcohol concentrations produces observable behavioral and cognitive teratogenic effects.1, 3, 7 Unlike chronic alcoholism, binge drinking appears to be a more socially acceptable behavior in many circumstances.8-10 The opportunities for unknowingly exposing a fetus to alcohol early in the first trimester may be great because more than half of US pregnancies are unintended,11 and many women are not aware of the fact that they are 1
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Fig 1. Prevalence of binge drinking among US women aged 18-44 years by pregnancy status, 1991-1995 (1994 was excluded from the analysis because alcohol data were not collected in most states that year).
pregnant until 6-8 weeks of gestation. An additional concern is that women who binge drink may increase their risk of unplanned pregnancy8-10 and therefore be more likely to expose a fetus to high peak blood alcohol concentrations. Although there are population estimates of alcohol consumption patterns during pregnancy, including frequent or heavy alcohol consumption, there is relatively little information available on the extent of perinatal binge drinking nationally. A recent review of reproductive health risks related to binge drinking during pregnancy pointed out a number of methodologic problems that have contributed to this lack of information.1 For example, most studies tend to establish the usual pattern, frequency, and amount of alcohol intake and neglect to ascertain high-level intake on infrequent occasions. Because fetal alcohol syndrome is associated with chronic drinking during pregnancy, even if information about binge drinking is available, it is often subsumed within an overall category of frequent or heavy alcohol use. Recent reports on alcohol drinking among pregnant women showed that most women included in the category of frequent drinkers are also binge drinkers.12 In addition, point prevalence estimates of binge drinking among pregnant women were 4 times higher in 1995 than in 1991.12 In this article we compare US rates of binge drinking among pregnant women with those among nonpregnant women of childbearing age for the years 1991-1995. We also examine the characteristics associated with binge drinking among pregnant and nonpregnant women. We based our analysis on cross-sectional data from 46 states. Material and methods Data for this analysis are from the Behavioral Risk Factor Surveillance System (BRFSS).13 The BRFSS, sponsored by the Centers for Disease Control and Prevention (CDC), is a state-based ongoing surveillance of modifiable risk factors
for chronic diseases and other leading causes of morbidity and mortality. The BRFSS is a telephone survey of the noninstitutionalized civilian population aged ≥18 years. The median response rate (ratio of completed interviews to the sum of completed interviews and refusals) across the 4-year study period ranged from 80% to 85%. Information on alcohol use was collected each year from 1991-1995, except in 1994. In 1991 and 1992 respondents were asked the following question about alcohol use: “Have you had any beer, wine, or liquor during the past month?” In 1993 and 1995 this question was reworded to the following: “During the past month, have you had at least one drink of any alcoholic beverage such as beer, wine, wine coolers, or liquor?” Respondents who answered yes to the opening question in 1991 and 1992 were then asked the following question on binge drinking: “Considering all types of alcoholic beverages, that is, beer, wine, and liquor as drinks, how many times during the past month did you have 5 or more drinks on an occasion?” For 1993 and 1995 the question on binge drinking was simplified to exclude the listing of examples of alcoholic beverages. The question on pregnancy status (“To your knowledge, are you now pregnant?”) was asked in the latter part of the interview, after the questions on alcohol use. For this analysis binge drinking was defined as a positive response to both of the above-mentioned questions on alcohol use. This analysis was restricted to women aged 18 to 44 years, who lived in one of the 46 states that collected alcohol use information consistently during all years of the study period. For this analysis we weighted the state-specific data to reflect the general population of all 46 states. Of a total of 113,795 women who completed interviews during this period, we excluded 9872 for whom information on pregnancy status was missing or who were unsure of their pregnancy status. Thus the final analysis included 103,923 women, of whom 4611 were pregnant
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(weighted percentage 5). The percentage of women who were pregnant changed little over the study years. The distribution of pregnant women by selected demographic characteristics was comparable with that of nonpregnant women, except for age, marital status, and employment status (Table I). Pregnant women were younger and more likely to be married than nonpregnant women. Consistent with national estimates,14 women aged ≤30 years accounted for about 70% of all pregnancies. We obtained the percentage of women who consumed any amount of alcohol in the month before the survey by pregnancy status. We obtained the percentage of women who binged among pregnant and nonpregnant women by calendar year and also by selected sociodemographic variables. Because there is a legal restriction on sale of alcohol products to persons <21 years old,15 we used 20 as the upper limit for the youngest age group. Because of the small sample size for pregnant women, we did not compare prevalence rates for sociodemographic subgroups by year. To assess the magnitude of the pregnancy-related reduction in binge drinking, we computed prevalence rate ratios for binge drinking by dividing the prevalence among pregnant women by the prevalence among nonpregnant women for each of the various sociodemographic subgroups. The prevalence rate ratio provides a proxy measure of pregnancy-related changes in the prevalence of binge drinking. Using the prevalence rate ratio we identified subgroups of women that showed the least and greatest pregnancy-related decreases in binge drinking rates. Higher prevalence rate ratios indicate a lower pregnancy-related reduction in binge drinking, and lower values indicate a higher pregnancy-related reduction in binge drinking. To determine how prevalent binge drinking is as a pattern of alcohol use among alcohol drinkers, we did a subanalysis of those women who reported consumption of any amount of alcohol by pregnancy status. To identify sociodemographic characteristics of women associated with greater risk of binge drinking, we used multiple logistic regression models separately for pregnant and nonpregnant women and computed odds ratios and their 95% confidence intervals. The independent variables were age, race, education, marital status, employment, household income, and tobacco smoking. We used SUDAAN for all statistical analyses.16 Because we chose to round off all results to 1 decimal place and because of the large sample size, some point estimates appear to be the same as their upper or lower confidence limits. A value of P < .05 was considered statistically significant. Results During the study period, 641 (13.7%) pregnant women and 52,654 (52.8%) nonpregnant women reported drinking alcohol in the month before the survey. Further, 93 (weighted percentage 1.9) pregnant women and 11,165 (weighted percentage 11.6) nonpregnant women re-
Table I. Demographics of women in BRFSS, 1991-1995*
Characteristic Age 18-20 y 21-30 y 31-44 y Race White Black Other Education ≤11 y High school College level Marital status Married Other Employment status Employed Student Other Annual household income <$20,000 $20,000-$50,000 >$50,000
Pregnant (n = 4611) (%†)
Nonpregnant (n = 99,312) (%†)
13.1 56.2 30.7
10.1 38.1 51.8
72.6 10.5 16.9
74.6 10.9 14.5
11.8 34.2 54.0
9.4 33.1 57.5
77.1 22.9
56.0 44.0
55.6 4.6 39.8
66.8 8.9 24.3
31.0 47.8 21.2
30.1 48.2 21.7
*1994 was excluded from the analysis because alcohol data were not collected in most states that year. †Percentages are weighted.
ported binge drinking. In the total sample of pregnant women 1.1% (or 57% of the 93 binge drinkers) binged ≥2 times and 0.5% binged ≥3 times in the month before the survey. In the total sample of nonpregnant women 5.9% (or 50% of the 11,165 binge drinkers) binged ≥2 times and 3.4% binged ≥3 times in the month before the survey. Time trends. In the total sample, among pregnant women the prevalence of binge drinking increased significantly from 0.7% (95% confidence interval 0.3-0.9) in 1991 to 2.9% (95% confidence interval 2.2-3.6) in 1995 but changed little among nonpregnant women (Fig 1). Among nonpregnant women the prevalence of binge drinking did not vary significantly over time in any of the sociodemographic subgroups studied (data not shown). Within the subset of 641 pregnant women who were alcohol drinkers, binge drinking as a pattern of drinking increased from 5.4% (95% confidence interval 4.1-6.3) in 1991 to 18.3% (95% confidence interval 17.2-19.6) in 1995. Within the subset of 52,654 nonpregnant women who were alcohol drinkers, binge drinking as a pattern of drinking varied little over time (range 21.0%-23.1%). Pregnancy-related reduction in binge drinking. Overall, pregnant women were about one fifth (prevalence rate ratio 0.2, 95% confidence interval 0.1-0.2) as likely to binge drink as nonpregnant women (Table II). However, the pregnancy-related reduction in binge drinking rates varied substantially by sociodemographic subgroups (Table II). Pregnancy-related reduction in the prevalence of binge drinking was least among black women
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Table II. Prevalence rates and prevalence rate ratios of binge drinking among pregnant and nonpregnant women, United States, 1991-1995* Weighted percentage Characteristic TOTAL
Age 18-20 y 21-30 y 31-44 y Statistical significance Race White Black Other Statistical significance Education ≤11 y High school College level Statistical significance Marital status Married Other Statistical significance Employment status Employed Student Other Statistical significance Annual household income <$20,000 $20,000-$50,000 >$50,000 Statistical significance Tobacco smoking Never Past Current Statistical significance
Pregnant
Nonpregnant
Prevalence rate ratio
95% Confidence interval
1.9
11.6
0.2
0.1-0.2
2.1 1.6 2.2 P = .56
15.6 15.8 7.8 P < .01
0.1 0.1 0.3
0.1-0.3 0.1-0.3 0.2-0.4
1.7 3.4 1.8 P = .33
13.2 5.7 8.3 P < .01
0.1 0.6 0.2
0.1-0.2 0.4-1.0 0.1-0.4
1.1 2.2 1.9 P = .23
10.7 11.5 11.9 P = .07
0.1 0.2 0.2
0.1-0.2 0.1-0.3 0.1-0.2
1.2 4.2 P < .01
7.5 17.0 P < .01
0.2 0.3
0.1-0.2 0.2-0.3
2.5 1.9 1.1 P = .03
12.1 17.3 8.4 P < .01
0.2 0.1 0.1
0.2-0.3 0.1-0.2 0.1-0.2
1.8 1.8 2.8 P = .60
13.7 11.5 10.9 P < .01
0.1 0.2 0.3
0.1-0.2 0.1-0.2 0.2-0.4
1.2 1.2 5.5 P < .01
7.4 12.9 21.2 P < .01
0.2 0.1 0.3
0.1-0.2 0.1-0.2 0.2-0.4
χ2 tests for homogeneity among subgroups were conducted separately for pregnant and nonpregnant women, and the results are indicated as P values below percentages for each category. Also, because of rounding, some point estimates appear to be the same as their confidence limits. *1994 was excluded from the analysis because alcohol data were not collected in most states that year. †Prevalence among pregnant women/Prevalence among nonpregnant women.
(prevalence rate ratio 0.6, 95% confidence interval 0.41.0) and was somewhat less than average among women aged ≥31 years and among current tobacco smokers. The largest pregnancy-related reduction in binge drinking (indicated by a low prevalence rate ratio) was among women aged ≤30 years and women who had quit smoking. Within the subset of women who were alcohol drinkers, pregnant women were nearly two thirds as likely as nonpregnant women to binge drink (13.8% of 641 vs 22.1% of 52,654, prevalence rate ratio 0.6, 95% confidence interval 0.3-0.9). Characteristics. Despite alcohol purchase and consumption being illegal for people <21 years old, the prevalence of binge drinking among pregnant women <21 years old was comparable to that among pregnant women in the other age groups (P = .56). However,
among nonpregnant women <21 years old the prevalence of binge drinking was significantly higher than that among nonpregnant women aged 31-44 years (Table II). Subgroups of pregnant and nonpregnant women at increased risk for binge drinking were similar in the univariate analysis and in the multivariate logistic regression model (Tables II and III). For pregnant women the subgroups were unmarried, employed, or current smokers. For nonpregnant women the subgroups were age ≤30 years, nonblack race, unmarried, employed, student, or current-prior tobacco smoker, except for annual household income of ≤$20,000, which was only significant in the univariate analysis. Prior tobacco smoking was associated with binge drinking only among nonpregnant women (odds ratio 1.9, 95% confidence interval 1.8-2.0), whereas current tobacco smoking was associated with
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Table III. Multiple logistic regression estimates* of odds ratios for binge drinking among subgroups of pregnant and nonpregnant women, 1991-1995† Pregnant
Characteristic Age 18-20 y 21-30 y 31-44 y Race White Black Other Education ≤11 y High school College level Marital status Married Other Employment status Employed Student Other Annual household income <$20,000 $20,000-$50,000 >$50,000 Tobacco smoking Never Past Current
Nonpregnant
95% Confidence interval
Odds ratio
0.7 1.0 1.2
0.3-1.5 Referent 0.7-1.9
1.6 1.9 1.0
1.5-1.8 1.8-2.0 Referent
1.0 1.1 1.2
Referent 0.6-2.2 0.7-2.3
2.5 1.0 2.0
2.3-2.7 Referent 1.8-2.2
1.0 0.7 0.9
Referent 0.2-3.2 0.2-4.0
1.0 1.2 1.2
Referent 1.0-1.4 1.1-1.5
1.0 4.2
Referent 2.6-7.0
1.0 2.1
Referent 2.0-2.2
2.1 2.2 1.0
1.3-3.6 0.9-5.8 Referent
1.4 1.5 1.0
1.3-1.4 1.4-1.7 Referent
1.0 1.2 1.3
Referent 0.7-2.0 0.6-2.7
1.0 1.0 1.0
1.0-1.1 1.0-1.1 Referent
1.0 1.1 3.5
Referent 0.6-2.1 2.1-5.7
1.0 1.9 3.2
Referent 1.8-2.0 3.1-3.3
Odds ratio
95% Confidence interval
Reference groups were chosen as the subgroups of women with the smallest prevalence rates (as shown in Table II) and were different for pregnant and nonpregnant women. Because of rounding, some point estimates appear to be the same as their confidence intervals. *Adjusted for age, race, education, marital status, employment status, annual household income, and tobacco smoking. †1994 was excluded from the analysis because alcohol data were not collected in most states that year.
binge drinking among both pregnant (odds ratio 3.5, 95% confidence interval 2.1-5.7) and nonpregnant (odds ratio 3.2, 95% confidence interval 3.1-3.3) women. Comment To our knowledge this is the first study of binge drinking by pregnant women in the United States that has used a representative national sample. In this sample of women aged 18-44 years we found that pregnant women were one fifth as likely as nonpregnant women to binge drink. At least half of pregnant and nonpregnant binge drinkers reported binge drinking on ≥2 occasions in the month before the survey. This analysis also documents an overall increase from 1991 through 1995 in reported binge drinking among pregnant women that was not found among nonpregnant women. Direct comparison of prevalence rates of binge drinking found in the BRFSS with those found in other surveys on alcohol use is difficult because of variations in survey design and the absence of information on pregnancy in many surveys. The National Household Survey on Drug Abuse (NHSDA) collected pregnancy data from women
aged 15 to 44 years in 1994 and 1995.17 In that survey the prevalence of binge drinking for 1994 and 1995 combined was similar to that found in our study for 1995 among pregnant women (2.9% vs 2.9%) but slightly higher among nonpregnant women (15.8% vs 11.6%).17 The NHSDA’s higher prevalence of binge drinking among nonpregnant women may be because the NHSDA oversampled some subgroups of women and had a wider age range (15-44 years) than our survey population (18-44 years). The recent increase that we found in binge drinking by pregnant women reflects the increases in consumption of any amount of alcohol reported among women in the NHSDA17 and among pregnant women in the BRFSS.12 The NHSDA showed a slight increase in any alcohol consumption, from 41.4% in 1992 to 45.0% by 1995 among US women aged ≥12 years.17 The disproportionate increases in reported binge drinking among pregnant alcohol users suggests that binge drinking is becoming a more popular pattern of alcohol use among pregnant women. Previously suggested explanations for these recent increases in binge drinking include increasing recent reports on the health benefits of moder-
6 Ebrahim et al
ate alcohol drinking and a relative increase in alcohol promotion efforts compared with public health interventions to reduce drinking.18 Although 90% of women are aware that alcohol use during pregnancy can damage the fetus,19 it is not known whether women believe that binge drinking carries as much risk as frequent or daily drinking. The rephrasing of the alcohol questions from 1993 on may have affected the reported rates of binge drinking: The opening question on drinking in the 1993 survey was more specific than that on the earlier surveys, which could have led to an increase in the percentage of women who reported drinking. On the other hand, the rephrasing of questions on binge drinking in 1993, which excluded examples of alcoholic beverages, could actually have led to a decrease in the percentage of women who reported binge drinking and not an increase. Because the rephrasing of the alcohol questions did not affect the rates in alcohol use among nonpregnant women in a magnitude similar to that in pregnant women, further studies are needed to determine whether pregnant and nonpregnant women respond differently to rephrasing of alcohol questions. An important strength of this study is that the question on pregnancy was asked well after questions on alcohol use had been asked. Most women know that alcohol adversely affects pregnancy, 19 and such knowledge may lead women to deny alcohol use if the alcohol questions were asked after the question on pregnancy. The known self-report bias in relation to alcohol use20 is reported to be largely limited to very heavy alcohol users21 and may not affect the reporting of occasional consumption of alcohol, which may be considered socially desirable.8-10 In this survey alcohol use histories were only obtained for the preceding month, leading us to classify women who drank alcohol earlier than that month as nondrinkers. In addition, the duration of time for each binge drinking “occasion” was not specified. Despite these limitations, given that the vast majority of states were included in this survey, these data provide the best available estimate of the extent of binge drinking in relation to pregnancy in the United States. People <21 years old have been found to have equal access to alcohol when compared with other age groups, despite legal restrictions on the sale of alcohol to minors.15 This high rate of alcohol exposure among minors complicates efforts to reduce alcohol-exposed pregnancies, because young women have the highest rates of unintended pregnancies (teenagers 82%, women aged 2024 years 61%)11 and are thus more likely to unknowingly expose the fetus to high levels of alcohol. Of relevance also is the fact that binge drinking is associated with other factors such as unsafe sex, sexually transmitted infections, and physical injuries that place women who binge at increased risk for adverse reproductive, pregnancy, and other poor health outcomes.22 The finding that black women had the lowest preg-
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nancy-associated reduction in binge drinking (the prevalence rate ratio was 0.6 in black women vs 0.2 in the overall sample) is of concern and has not been previously shown. This finding on binge drinking contrasts with the finding that pregnancy-associated reduction in smoking was greatest among black women.23 Although the prevalence of any alcohol consumption was reported to be significantly higher among white women than among black women, such a difference was not reported for heavy drinking.24 Thus among the relatively few black women who drink there may be a heavier concentration of problem drinkers than among white women. Problem drinkers are also less likely to perceive drinking during pregnancy as a risk for adverse outcomes25 and are therefore less likely to reduce alcohol consumption while pregnant. Most of the other subgroups of women whose pregnancy-related reduction in binge drinking was smaller than that in the overall sample were also found to be at higher risk for binge drinking in the multiple logistic regression analysis. The characteristics of pregnant women that were associated with a high prevalence of binge drinking—unmarried, employed, and current smoking—were also found in our previous analysis of the BRFSS and by other reports on frequent drinking.18, 24 We did not find as high a prevalence of binge drinking among pregnant women who are young or who are students as have other researchers,9, 10 possibly because young women and students who are pregnant are underrepresented in the BRFSS. However, our findings did agree with earlier reports that younger age and being a student were associated with a higher prevalence of binge drinking among nonpregnant women. The prevalence of binge drinking among women who were young (15.7%) or students (17.2%) in the BRFSS was less than half the prevalence reported in a national survey on alcohol use among students on 140 campuses (39%).10 In that survey,10 however, binge drinking was defined as consumption of ≥4 drinks per occasion during the 2 weeks before the survey, whereas in the BRFSS binge drinking was defined as consumption of ≥5 drinks in the month before the survey. In addition, the low prevalence of binge drinking in the BRFSS, including among young women and students, may be the result of the exclusion of persons <18 years old, persons without telephones, and persons not living in private residences, such as those living in college dormitories. The recent increases in reported rates of binge drinking among pregnant women highlight the need for measures to sensitize women about the dangers of binge drinking during pregnancy. Efforts to reduce alcohol consumption among teenagers and young women may benefit from concerted programs focusing on family planning and the prevention of polydrug use and sexually transmitted diseases. Studies on the attitudes and practices of providers of preconcep-
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tion and prenatal care regarding binge drinking during pregnancy are clearly needed, as are studies on knowledge and attitudes of women of childbearing age concerning the effects of binge drinking on pregnancy outcomes. Individual providers of prenatal and periconceptional care can play important roles in counseling women who are likely to binge on the adverse effects of binge drinking on pregnancy. Public health agencies should increase their efforts to educate women of reproductive age about the general adverse health effects of this drinking pattern, as well as the risk it poses to any child they may conceive. We acknowledge the state coordinators of the Behavioral Risk Factor Surveillance System and the Behavioral Risk Factor Surveillance Branch of the National Center for Chronic Disease Prevention, CDC, without whose help the data would not have been available. We are indebted to Elizabeth Luman and Mike Tully for programming support. We also thank Gregg Leeman for conducting a literature search and Dr Coleen Boyle and Ms Kim Van Naarden for reviewing the manuscript. REFERENCES
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