Correspondence
Number of Pregnancies and Risk of Cardiovascular Disease
N Engl J Med 1993; 329:1893-1895December 16, 1993
- Article
To the Editor:
In their study of the relation between the number of pregnancies and the risk of cardiovascular disease (May 27 issue), Ness et al. found that having six or more pregnancies was associated with a small but consistent increase in the risk of coronary heart disease and cardiovascular disease1. The authors state that their findings have been adjusted for educational level but do not specify the statistical method used. Were high-school years and elementary-school years weighted equally? The educational level of the subgroup with six or more pregnancies was significantly lower than that of the other subgroups in both the Framingham Heart Study and the National Health and Nutrition Examination Survey National Epidemiologic Follow-up Study (NHEFS). The chief difference was in the percentage of women who attended high school. There is an association between educational level and the risk of coronary artery disease2,3. The assertion that multigravidity is associated with an increased risk of cardiovascular disease may just be a reassertion of an already established concept.
3 ReferencesJeffrey A. Grinblatt, M.D.
Rush North Shore Medical Center, Skokie, IL 600761
Ness RB ,Harris T ,Cobb J , et al. Number of pregnancies and the subsequent risk of cardiovascular disease. N Engl J Med 1993;328:1528-1533
Full Text | Web of Science | Medline2
Winkleby MA ,Jatulis DE ,Frank E ,Fortmann SP . Socioeconomic status and health: how education, income, and occupation contribute to risk factors for cardiovascular disease. Am J Public Health 1992;82:816-820
CrossRef | Web of Science | Medline3
MacDonald S ,Joffres MR ,Stachenko S ,Horlick L ,Fodor G . Multiple cardiovascular disease risk factors in Canadian adults. Can Med Assoc J 1992;146:2021-2029
Web of Science
To the Editor:
Ness et al. reported an association between the number of pregnancies and the risk of coronary heart disease. The association was independent of known risk factors and educational level. The authors focus on physiologic explanations and mention the possibility of a causal relation mediated by insulin resistance.
We have examined both the number of children and the number of pregnancies in relation to mortality from coronary heart disease in a 28-year follow-up study of Dutch civil servants and their spouses.1 In a health survey conducted in 1953-1954, 1200 married women 40 to 65 years of age were asked about the number of their pregnancies and miscarriages. The number of children was calculated by subtracting the second number from the first. As shown in Table 1Table 1
Mortality from Coronary Heart Disease According to Sex and Number of Pregnancies or Number of Children., the relative rate of mortality from coronary heart disease among women who had had four or more pregnancies as compared with women who had never been pregnant was 1.4 (95 percent confidence interval, 0.6 to 3.3), whereas when women with four or more children were compared with women with no children the rate was 2.5 (95 percent confidence interval, 1.0 to 5.8). This might be taken to show that some physiologic effect is more prominent in full-term pregnancies, but it could also indicate a role for the social or emotional factors associated with raising children.To clarify this issue further, we studied the 1048 husbands who also participated in the study. Interestingly, men with four or more children also had higher mortality from coronary heart disease, although it was somewhat lower than that of the women and not significantly different from 1 (rate ratio, 1.6; 95 percent confidence interval, 0.9 to 2.6). Fifteen-year mortality from coronary heart disease, which could be evaluated only in men, was higher (rate ratio, 2.1; 95 percent confidence interval, 0.9 to 5.2).
These data seem to indicate that besides the pregnancy-related factors mentioned by Ness et al., social factors (e.g., those related to lifestyle) and socioeconomic or emotional factors may make an important contribution to the association between the number of pregnancies and the risk of coronary heart disease among women.
1 ReferencesJacqueline M. Dekker, M.Sc.
Evert G. Schouten, Ph.D., M.D.
Wageningen Agricultural University, 6700 AE Wageningen, the Netherlands1
Schouten EG ,Dekker JM ,Meppelink P ,Kok FJ ,Vandenbroucke JP ,Pool J . QT interval prolongation predicts cardiovascular mortality in an apparently healthy population. Circulation 1991;84:1516-1523
Web of Science | Medline
To the Editor:
Ness et al. reported an increased risk of cardiovascular disease among women with high parity. We reported similar results from a case-control study of nonfatal myocardial infarction that included 858 women with first infarctions and 858 control women from the community.1 Among all the women with children, the estimate of the relative risk for women with five or more births as compared with fewer than five births was 1.4 (95 percent confidence interval, 1.0 to 2.0). In addition, women who had their first term pregnancy before the age of 20 had an increased risk as compared with women who had a first delivery later (relative risk, 1.7; 95 percent confidence interval, 1.1 to 2.6). The association of high parity with an increased risk of nonfatal myocardial infarction was strongest among women who first gave birth before the age of 20 (relative risk, 2.3; 95 percent confidence interval, 1.1 to 5.2); among those who first gave birth at a later age, the estimated relative risk for women with high parity was 1.2. If information on women's age at the first delivery is available in the data analyzed by Ness et al., it would be of interest to determine whether there are analogous findings.
1 ReferencesJulie R. Palmer, Sc.D.
Lynn Rosenberg, Sc.D.
Samuel Shapiro, M.B.
Boston University School of Medicine, Brookline, MA 021461
Palmer JR ,Rosenberg L ,Shapiro S . Reproductive factors and risk of myocardial infarction. Am J Epidemiol 1992;136:408-416
Web of Science | Medline
Author/Editor Response
The authors reply:
To the Editor: We were pleased to learn that two other groups have additional findings pertinent to gravidity and coronary heart disease. Their results and ours are consistent in showing an increase in risk of about 40 to 60 percent in women with multiple pregnancies, even after adjustment for other risk factors associated with coronary heart disease. Although our discussion focused on possible biologic mediators of the relation between multigravidity and coronary heart disease, we agree that equally likely explanations include non-biologic factors, such as stress and changes in lifestyle. The consistency of the finding between studies suggests that further exploration of this area may prove useful, especially with regard to possible mechanisms of mediation.
In particular, the finding by Dekker and Schouten of an increase in coronary heart disease with the number of children among men begins to contribute data toward addressing alternative mechanisms. The results are difficult to interpret, however, because the relation was less strong among men than among women and was attenuated over time. Further study of this finding in men, independent of other known risk factors for coronary heart disease, would be of interest in order to discern whether the increase is consistent among studies.
Because possible confounding by socioeconomic status was an important concern in our study, we adjusted for education as a measure of socioeconomic status in the multivariate analyses. In response to Dr. Grinblatt's query, in the Framingham Heart Study there were nine categories ranging from no education to post-college training. In the NHEFS, there were three categories: less than 9 years of education, 9 to 12 years, and more than 12 years. In other studies with similar results, socioeconomic status was controlled for differently. The consistency of the results among studies using various adjustments for socioeconomic status suggests that the association between gravidity and coronary heart disease cannot be entirely explained by socioeconomic status. Indeed, it suggests that reproductive history is an important consideration in the health risks of women.
Roberta B. Ness, M.D., M.P.H.
Tamara Harris, M.D., M.S.
Janet Cobb, M.P.H.
University of Pittsburgh, Pittsburgh, PA 15261- Citing Articles (16)
Citing Articles
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M. L. Eisenberg, Y. Park, A. R. Hollenbeck, L. I. Lipshultz, A. Schatzkin, M. J. Pletcher. (2011) Fatherhood and the risk of cardiovascular mortality in the NIH-AARP Diet and Health Study. Human Reproduction 26:12, 3479-3485
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Dena H. Jaffe, Zvi Eisenbach, Orly Manor. (2011) The Effect of Parity on Cause-Specific Mortality Among Married Men and Women. Maternal and Child Health Journal 15:3, 376-385
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Nisha I. Parikh, Sven Cnattingius, Paul W. Dickman, Murray A. Mittleman, Jonas F. Ludvigsson, Erik Ingelsson. (2010) Parity and risk of later-life maternal cardiovascular disease. American Heart Journal 159:2, 215-221.e6
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Elham Mousavi, Mojgan Gharipour, Aliakbar Tavassoli, Gholam Hosein Sadri, Nizal Sarrafzadegan. (2009) Multiparity and Risk of Metabolic Syndrome: Isfahan Healthy Heart Program. Metabolic Syndrome and Related Disorders 7:6, 519-524
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Erica P. Gunderson, David R. Jacobs, Vicky Chiang, Cora E. Lewis, Ailin Tsai, Charles P. Quesenberry, Stephen Sidney. (2009) Childbearing is associated with higher incidence of the metabolic syndrome among women of reproductive age controlling for measurements before pregnancy: the CARDIA study. American Journal of Obstetrics and Gynecology 201:2, 177.e1-177.e9
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Dena H. Jaffe, Yehuda D. Neumark, Zvi Eisenbach, Orly Manor. (2009) Parity-related mortality: shape of association among middle-aged and elderly men and women. European Journal of Epidemiology 24:1, 9-16
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Femke Atsma, Marie-Louise E.L. Bartelink, Diederick E. Grobbee, Annemarieke Rutten, Michiel L. Bots, Matthias Prokop, Yvonne T. van der Schouw. (2008) Reproductive factors, metabolic factors, and coronary artery calcification in older women. Menopause 15:5, 899-904
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R Hardy, DA Lawlor, S Black, MEJ Wadsworth, D Kuh. (2007) Number of children and coronary heart disease risk factors in men and women from a British birth cohort. BJOG: An International Journal of Obstetrics & Gynaecology 114:6, 721-730
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Füsun Taşkın, Alev Akdilli, Can Karaman, Alparslan Ünsal, Kutsi Köseoğlu, Filiz Ergin. (2006) Mammographically detected breast arterial calcifications: Indicators for arteriosclerotic diseases?. European Journal of Radiology 60:2, 250-255
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X. Q. Lao, G. N. Thomas, C. Q. Jiang, W. S. Zhang, P. Yin, M. Schooling, M. Heys, G. M. Leung, P. Adab, K. K. Cheng, T. H. Lam. (2006) Parity and the metabolic syndrome in older Chinese women: the Guangzhou Biobank Cohort Study. Clinical Endocrinology 65:4, 460-469
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Scott M Nelson, Ian A Greer. (2006) Hypertensive disorders of pregnancy: preventative-, immediate- and long-term management. Expert Review of Pharmacoeconomics & Outcomes Research 6:5, 541-554
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T E Blaudeau, G R Hunter, B Sirikul. (2006) Intra-abdominal adipose tissue deposition and parity. International Journal of Obesity 30:7, 1119-1124
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Lori A. Bastian, Nancy A. West, Chris Corcoran, Ronald G. Munger. (2005) Number of children and the risk of obesity in older women. Preventive Medicine 40:1, 99-104
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Haoling H. Weng, Lori A. Bastian, Donald H. Taylor, Barry K. Moser, Truls Ostbye. (2004) Number of Children Associated with Obesity in Middle-Aged Women and Men: Results from the Health and Retirement Study. Journal of Women's Health 13:1, 85-91
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Donna Kritz-Silverstein, Elizabeth Barrett-Connor, Nancylee J. Friedlander. (1997) Parenthood and lipid and lipoprotein levels in older men. Annals of Epidemiology 7:4, 275-279
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Nancylee J. Friedlander. (1996) The relation of lifetime reproduction to survivorship in women and men: A prospective study. American Journal of Human Biology 8:6, 771-783
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