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,2
* Post-Graduate Program in Epidemiology, Universidade Federal de Pelotas, CP 464, 96001–970, Pelotas, RS, Brazil and
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853
2To whom correspondence should be addressed. E-mail: denise{at}epidemio-ufpel.org.br.
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ABSTRACT |
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 TOP ABSTRACT METHODSRESULTSDISCUSSIONLITERATURE CITED |
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KEY WORDS: • adolescence • pregnancy • nutritional status • BMI • cohort studies
The prevalence of obesity has increased worldwide as a result of the rapid nutritional transition observed in many countries (1). Among adolescents, the age group between 10 and 19 y old, increased weight and height have been documented even in less-developed regions (2). Data from developed countries suggest that the diet of adolescents puts them at risk for chronic diseases, such as cardiovascular disease, diabetes, cancer, and osteoporosis (3). From the perspective of prevention, the identification of groups of people at risk of becoming obese has been considered an important concern in research. In a systematic review that included studies of childhood predictors of adult obesity, Parsons and colleagues (4) concluded that the lack of longitudinal data from childhood to adulthood is the major research gap.
Likewise, many developing countries are experiencing an increase in the rate of adolescent pregnancy. In Brazil, there were 8.0 births per 1000 adolescents in 1980, which increased 14% to 9.1 in 2000. Among all births, the increase in the proportion of adolescent mothers has been even sharper. In 1980, 9.1% of all births were among adolescent mothers, and this proportion more than doubled, to 19.4% in 2000 (5).
The consequences of teenage pregnancy for adult nutritional status have been little studied in developing countries as a result of the lack of longitudinal studies. Evidence from developed countries suggests that adolescents grow while pregnant and that their growth is associated with increased weight gain and fat storage. Scholl and colleagues (6), in the Camden study, showed that the amount of postpartum retained weight was significantly greater in still-growing gravidas than in other pregnant women. Growth in stature continues after menarche (7,8) and during teenage pregnancy. In the Camden Study, growth in stature was detected on the basis of a knee height measuring device to eliminate the effect of shrinkage in stature during pregnancy. Adolescents had significantly positive increments compared with mature gravidas (9).
In Pelotas, a city in southern Brazil, girls have been studied since their birth in 1982. In 2001, the risk factors for childbearing during adolescence were studied in this cohort (10). A total of 16% of the girls who belonged to the cohort study gave birth up to 2001. Anthropometric variables were measured since birth.
The purpose of the research reported here was to study the effects of teenage pregnancy on nutritional status at age 19 in a subsample of female adolescents that was followed from 1982 to 2001. The Pelotas Birth Cohort Study allows examining these associations, while accounting for some of the possible confounding factors that have not been considered in many studies.
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METHODS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONLITERATURE CITED |
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The research described here involved female adolescents who belonged to the Cohort Study and who were examined in both 1997 and 2001. In 1997, a systematic sample of 27% of all households in the city was visited in search of adolescents who were born in 1982. It resulted in the identification of 515 female adolescents, who were also visited in 2001. In this latest follow-up, 502 girls were located, representing 97.5% of those located in 1997. Of the subcohort of female adolescents who were seen in both 1997 and 2001, 38 were excluded because they were pregnant at the time of the 2001 interview (n = 24), had a child before 1997 (n = 4), had a child in the last 6 mo (n = 5), or had missing information in anthropometric variables (n = 5). All analyses were based on the remaining 464 young women.
Data collection. In all phases of this cohort study, a group of field workers was trained in interview techniques and anthropometry. The enrollment of the Birth Cohort Study took place in the maternity hospital, and follow-ups were conducted in the girls’ households. Informed consent was obtained in all phases of the study, and the adolescent and her mother gave their consent in this phase of the cohort study. The study was approved by the maternity hospitals’ ethical committees and by the university ethical committee.
Information concerning the mother and her pregnancy was obtained at enrollment in 1982 and was collected at the maternity hospitals up to 3 d after birth. Information concerning the children was obtained through standardized questionnaires given to their mothers in 1984 and in 1986 at mean ages of 2 and 4 y, respectively. Mothers of the study subjects were weighed and measured in the maternity hospitals. Their weight at the beginning of pregnancy was obtained by recall or, if available, collected from the antenatal card. Children were weighed in the maternity hospital and in all follow-up contacts. Length or height (as appropriate) was measured at each follow-up. In the 1997 and 2001 follow-up contacts, questionnaires were applied to both the adolescents and their mothers. Mean ages were 15 and 19 y in 1997 and 2001, respectively.
In all phases, a fieldwork supervisor repeated 5% of the interviews. These findings were compared with the original, ensuring the quality control.
Variables.
This analysis included variables from different phases of this cohort study. The variables collected in 1982 were family income (the sum of monthly incomes of all working people living in the household in minimal wage, categorized as 
1 minimal wage, 1.1 to 3, 3.1 to 6, and >6 minimal wages), maternal skin color (white or nonwhite), maternal age (categorized as <20; 20 to 29; and 
30 y), pregestational weight (from the antenatal care register or by asking the mother about her weight before pregnancy), maternal height (measured soon after admission to the maternity hospital), and birth weight (measured in grams immediately after birth by trained interviewers, using regularly calibrated pediatric scales). Children were weighed using portable scales (CMS Weighing Equipment) and had their supine length (1984) or height (1986) measured using boards manufactured locally according to international specifications (AHRTAG). BMI at ages 2 and 4 y were calculated by dividing weight by the square of height measured in 1984 and 1986, respectively. To define overweight in childhood and adolescence, dichotomous variables were used according to the recommended cutoff values by age (15). In 1984, the age of children varied from 12 to 27 mo and in 1986, from 36 to 51 mo. In 1997 and 2001, these ranges were 19 and 20 mo, respectively.
The variables collected during adolescence included BMI based on weight and height measured at ages 15 and 19 y, skin color reported by adolescent in 1997, and age at menarche (continuous variable, collected in 1997 and confirmed in 2001, divided into 4 categories: <12,12,13,and 14 y). Whether there was a pregnancy between 1997 and 2001 was obtained by asking the adolescent in the interviewer-applied questionnaire and in a confidential questionnaire. In this later questionnaire, information about abortion could be more precise. The higher number of pregnancies was used in the analyses.
The outcomes variables were changes in height, weight, and BMI between 1997 and 2001. Seven girls were excluded from the analyses because their change in height or weight was 3 SD or more above or below the mean change for the whole sample; these were likely to represent major measurement errors (16).
Statistical methods.
To describe the sample, frequency distributions were used to compare main variables collected in earlier phases of the cohort study for all girls and for those who were included in this analysis. The 
2 test was used to compare these proportions. To examine associations, ANOVA and F test were used to compare mean values of anthropometric variables across different categories of explanatory variables. Multiple linear regression analyses were carried out for changes in height, weight, and BMI between 1997 and 2001. Potential confounding factors, including anthropometric measurements in childhood and age at menarche, were investigated and those that showed an association (P < 0.2) were taken to the multivariable analyses. Variables were included as continuous in the linear regression models. Age at menarche and teenage pregnancy were also assessed both as categorical variable (<12, 12, 13, or 14 y and none pregnancy, 1 or 2 pregnancies, respectively) and as dichotomous variables (12 vs. <12 y and yes vs. no, respectively). Interactions between socioeconomic and nutritional variables included in these models were tested jointly through the product of all variables. The same criterion of significance for confounding factors (P < 0.2) was used for interactions. Graphical analyses of the residuals were developed for the linear regression assumptions, and colinearity was tested through variance inflation factors analysis (17) and the STATA package (Intercooled Stata 8.0 for Windows, Stata) was used in the analyses. The regression model included all potential confounding variables, and results are shown for age at menarche and the occurrence of teenage pregnancy.
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RESULTS |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONLITERATURE CITED |
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BMI values were 16.8 ± 1.4 kg/m2, 16.2 ± 1.5 kg/m2, 21.5 ± 3.5 kg/m2, and 22.3 ± 4.5 kg/m2 at ages 2, 4, 15, and 19, respectively. Higher BMI values at ages 4, 15, and 19 were observed among girls who had early menarche [P < 0.001 (data not shown)].
Family income, birth weight, and overweight in childhood were positively associated with attained height in 2001 (Table 3). An inverse association was observed between teenage pregnancy and attained height (P = 0.002). Skin color, age at menarche, and maternal age were not associated with height.
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Change in weight was positively associated with age of the adolescent’s mother. Weight change was also greater among adolescents who were not overweight in 1986 (P = 0.01) and among those with later menarche (P < 0.001). The effect of pregnancy on weight change was not linear; weight gain was most pronounced among adolescents who had a single pregnancy (Table 3).
BMI change between 1997 and 2001 was inversely related to family income and directly related to age at menarche. Teenage pregnancy was positively associated with BMI change (P = 0.001), with a significant linear trend (Table 3).
In the adjusted analysis, height changes were significantly larger among girls with later menarche (Table 4). Each year for which menarche was delayed resulted in an increase of 0.47 cm in height (P < 0.001). When age at menarche was treated as a categorical variable, the effect was restricted to ages 13 y or greater. The dichotomous variable was also significant (P = 0.001). The continuous variable expressing the number of pregnancies showed that adolescents who had been pregnant were shorter than those who had never been pregnant (P = 0.02). Girls who were never pregnant were 0.40 cm (P = 0.11) taller than those with one or more pregnancies. Finally, categorical analysis showed that, compared with girls who were never pregnant, those who had 1 pregnancy were 0.18 cm shorter (P = 0.5) and those with 2 or more pregnancies were 1.60 cm shorter (P = 0.006). Therefore, the effect of pregnancy was restricted to those with more than 1 pregnancy.
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DISCUSSION |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONLITERATURE CITED |
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This study included all girls belonging to the cohort study who were identified in a cluster sample of 27% of all households in the city in 1997. We estimate that these represent 72% of the cohort adolescents who should have located in this sample of the city, in the absence of out-migration. Losses to follow-up were more common among the poorest families, when the adolescent herself had been born to an adolescent mother, and for low-birth-weight girls, which may be partly explained by survival bias. However, differences between those located and those lost to follow-up were not marked. A more detailed analysis of losses to follow-up is available elsewhere (14). Among female adolescents interviewed in 1997, 96.5% were seen again in 2001. Of all girls included in this study, only 4 adolescents had a term delivery before 1997. These teenage mothers were excluded in this analysis because pregestational nutritional status was unknown.
According to the official information systems for live and stillbirth in Pelotas, childbearing during adolescence was reported for 16.2% of all girls belonging to the original cohort. Among girls included in the present analyses, 16.9% delivered a baby between 1997 and 2001.
Teenage pregnancy is a time of nutritional risk (19). Adolescents most likely to become pregnant are often those with inadequate nutritional status and unfavorable socioeconomic background (20,21). Scholl and Hediger (22) showed that there is a competition for nutrients between the growing pregnant adolescent and her fetus. The present results confirmed a strong inverse association between pregnancy and change of height, especially among those who had 2 or more pregnancies.
Growth in stature continues after menarche and during teenage pregnancy (7,8,23). In this study, mean attained heights at the end of adolescence were similar for girls with zero or one pregnancy, but markedly shorter for those with 2 or more gestations. This suggests that there was a cumulative effect on growth in height that only became apparent for girls with 2 pregnancies.
Researchers have found that there is considerable weight gain and increase in subcutaneous fatness at central sites when pregnancy occurs during the final phase of adolescent growth (6,23,24). Some authors have documented that adolescent pregnancy is associated with larger gestational weight gains and increased risk for weight retention (25). The present results showed that having one or more pregnancies during adolescence was associated with weighing 2 kg more at age 19 y than not having any pregnancies.
Changes in BMI were a result of the combination of relative gains in weight and height. Girls with a single pregnancy gained more weight but did not gain more height than those who did not get pregnant. On the other hand, those with 2 or more pregnancies gained about the same amount of weight as those with a single pregnancy but gained considerably less height. Thus, BMI change was linearly related to the number of pregnancies.
In adult women, the findings are inconclusive with respect to excess weight gain and risk of becoming overweight associated with pregnancy. In adolescents, maternal growth accounts for some of the weight increase during pregnancy (26). Although most of the pubertal gains in stature in girls are around the time of peak height velocity, and, prior to menarche, growth continues during late adolescence, small and positive increments in stature were observed in adolescents during pregnancy (7,8,23). Hediger and colleagues (8) have documented that adolescent pregnancy is associated with larger gestational weight gains. They found that, after week 28, growing adolescents on average failed to lose fat and tended to continue to accrue fat in their upper arm fat area. In contrast, mature women and the nongrowing adolescents both lost fat from their upper arms and back. Thus, continued subcutaneous fat accrual after week 28, at a time when reductions in the subcutaneous fat mass are expected, appears to be characteristic of maternal growth during pregnancy. In the present study, linear association between BMI gain and pregnancy was related to both reduced height and increased weight. In another Brazilian study, Sichieri and co-workers (27) used 1996 Demographic Health Survey data on 2297 women aged 20 to 45 y and showed that short stature was associated with an increased risk of weight gain with pregnancy in the developed areas of Brazil.
Some limitations must be considered when interpreting these data. Only 12 adolescents had had 2 or more pregnancies, and the possibility of lack of statistical power must be considered, particularly for the analyses of weight change. Also, the 1997 follow-up was restricted to 27% of the urban area, and 28% of the original cohort was lost to follow-up. If we had been able to include all of the female adolescents who were born in 1982 (2876 girls) in this follow-up, the number of adolescents who were pregnant and the power of the study would have been greater, which may have permitted us to identify additional associations with weight change.
In summary, the negative effect of pregnancy on height change was restricted to adolescents who had 2 or more pregnancies, while greater gains in weight and BMI were observed among all of those who became pregnant. Both by reducing adult height and increasing overweight, teenage pregnancy may contribute to the prevalence of obesity and the incidence of chronic diseases from adolescence to adulthood (28,29). Using existing data on the distribution of BMI among adult Pelotas women (30), it is possible to estimate the impact of teenage pregnancy. Currently, 54.2% of Pelotas women are overweight. If one assumes a normal distribution of BMI, a shift of 1.58 kg/m2 in a group of this population and, consequently, a shift of 0.29 Z score, would increase the prevalence of overweight in this group to 65.5%. So, efforts to reduce teenage pregnancy may also contribute to prevent overweight, taking into account the growing epidemic of obesity in low- and middle-income countries, particularly among women.
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FOOTNOTES |
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Manuscript received 16 August 2004. Initial review completed 1 September 2004. Revision accepted 11 October 2004.
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LITERATURE CITED |
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TOPABSTRACTMETHODSRESULTSDISCUSSIONLITERATURE CITED |
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1. Popkin, B. M. & Doak, C. M. (1998) The obesity epidemic is a worldwide phenomenon. Nutr. Rev. 56:106-114.[Medline]
2. Schneider, D. (2000) International trends in adolescent nutrition. Soc. Sci. Med. 51:955-967.
3. Lytle, L. A. (2002) Nutritional issues for adolescents. J. Am. Diet. Assoc. 102:S8-12.[Medline]
4. Parsons, T. J., Power, C., Logan, S. & Summerbell, C. D. (1999) Childhood predictors of adult obesity: a systematic review. Int. J. Obes. Relat. Metab. Disord. 23:S1-S107.
5. IBGE () Censo Demografico 2000: fecundidade e mortalidade infantil. Resultados preliminares IBGE Rio de Janeiro, Brazil .
6. Scholl, T. O., Hediger, M. L., Schall, J. I., Khoo, C. S. & Fisher, R. L. (1994) Maternal growth during pregnancy and the competition for nutrients. Am. J. Clin. Nutr. 60:183-188.
7. Frisancho, A. R. (1997) Reduction of birth weight among infants born to adolescents: maternal-fetal growth competition. Ann. N.Y. Acad. Sci. 817:272-280.[Medline]
8. Hediger, M. L., Scholl, T. O. & Schall, J. I. (1997) Implications of the Camden Study of adolescent pregnancy: interactions among maternal growth, nutritional status, and body composition. Ann. N.Y. Acad. Sci. 817:281-291.[Medline]
9. Scholl, T. O., Hediger, M. L. & Schall, J. I. (1997) Maternal growth and fetal growth: pregnancy course and outcome in the Camden Study. Ann. N.Y. Acad. Sci. 817:292-301.[Medline]
10. Gigante, D. P., Victora, C. G., Gonçalves, H., Lima, R. C., Barros, F. C. & Rasmussen, K. M. (2004) Risk factors of childbearing during adolescence in a population-based birth cohort in southern Brazil. Rev. Panam. Salud Publica 16:1-10.[Medline]
11. Victora, C. G., Barros, F. C. & Vaughan, J. P. (1989) Epidemiologia da Desigualdade 1989 Hucitec Sao Paulo, Brazil .
12. Barros, F. C., Victora, C. G. & Vaughan, J. P. (1990) The Pelotas birth cohort study, 1982–1987. Strategies for following up 6,000 children in a developing country. Paediatr. Perinat. Epidemiol. 4:267-282.
13. Barros, F. C., Victora, C. G., Vaughan, J. P., Tomasi, E., Horta, B. L., Cesar, J. A., Menezes, A.M.B., Halpern, R., Post, C. L. & Garcia, M. M. (2001) The epidemiologic transition in maternal and child health in a Brazilian city, 1982–1993: a comparison of two population-based cohorts. Paediatr. Perinat. Epidemiol. 15:4-11.[Medline]
14. Victora, C. G, Barros, F. C., Lima, R. C., Behague, D., Gonçalves, H., Horta, B. L., Gigante, D. P. & Vaughan, J. P. (2003) The Pelotas (Brazil) Birth Cohort Study, 1982–2001. Cad. Saude Publica 19:1241-1256.[Medline]
15. Cole, T. J., Bellizzi, M. C., Flegal, K. M. & Dietz, W. H. (2000) Establishing a standard definition for child overweight and obesity worldwide: international survey. Br. Med. J. 320:1240-1243.
16. lsqb;WHO] World Health Organization (1995) Physical status: the use and interpretation of anthropometry. Technical Report Series 854 1995 WHO Geneva, Switzerland .
17. Kleinbaum, D. G., Kupper, L. L., Muleer, K. E. & Nizam, A. (1998) Applied Regression Analysis and Other Multivariate Methods 3rd ed. 1998 Duxbury Press Pacific Grove, CA .
18. Harpham, T., Huttly, S., Wilson, I. & De Wet, T. (2003) Linking public issues with private troubles: panel studies in developing countries. J. Int. Dev. 15:1-11.
19. Lederman, S. A. (1997) Nutritional support for the pregnant adolescent. Ann. N.Y. Acad. Sci. 817:304-312.[Medline]
20. Lawlor, D. A. & Shaw, M. (2002) Too much too young? Teenage pregnancy is not a public health problem. Int. J. Epidemiol. 31:552-554.
21. Smith, S. (2002) Too much too young? In Nepal more a case of too little, too young. Int. J. Epidemiol. 31:557-558.
22. Scholl, T. O. & Hediger, M. L. (1993) A review of the epidemiology of nutrition and adolescent pregnancy: maternal growth during pregnancy and its effect on the fetus. J. Am. Coll. Nutr. 12:101-107.[Abstract]
23. Garn, S. M., Lavelle, M., Pesick, S. D. & Ridella, S. A. (1984) Are pregnant teenagers still in rapid growth?. Am. J. Dis. Child. 138:32-34.
24. Scholl, T. O., Hediger, M. L., Schall, J. I., Mead, J. P. & Fischer, R. L. (1995) Maternal growth during adolescent pregnancy. J. Am. Med. Assoc. 274:26-27.
25. Olson, C. M., Strawderman, M. S., Hinton, P. S. & Pearson, T. A. (2003) Gestational weight gain and postpartum behaviors associated with weight change from early pregnancy to 1 y postpartum. Int. J. Obes. Relat. Metab. Disord. 27:117-127.[Medline]
26. Gunderson, E. P. & Abrams, B. (2000) Epidemiology of gestational weight gain and body weight changes after pregnancy. Epidemiol. Rev. 22:261-274.
27. Sichieri, R., Silva, C.V.C. & Moura, A. S. (2003) Combined effect of short stature and socioeconomic status on body mass index and weight gain during reproductive age in Brazilian women. Braz. J. Med. Biol. Res. 36:1319-1325.[Medline]
28. Allebeck, P. & Bergh, C. (1992) Height, body mass index and mortality: do social factors explain the association?. Public Health 106:375-382.[Medline]
29. Must, A., Jacques, P. F., Dallal, G. E., Bajema, C. J. & Dietz, W. H. (1992) Long-term morbidity and mortality of overweight adolescents. A follow-up of the Harvard Growth Study of 1922 to 1935. N. Engl. J. Med. 327:1350-1355.[Abstract]
30. Gigante, D. P., Barros, F. C., Post, C. L. & Olinto, M. T. (1997) Prevalence and risk factors of obesity in adults. Rev. Saude Publica 31:236-246.[Medline]
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