BMJ No 7106 Volume 315
Papers Saturday 23 August 1997
Size at birth, maternal nutritional status in pregnancy, and blood pressure at age 17: population based analysis
Arie Laor, David K Stevenson, Jeoshua Shemer, Rena Gale, Daniel S Seidman
Abstract
Objective: To assess the effect of size at birth, maternal nutrition, and body mass index on blood pressure in late adolescence.Design: Population based analysis of birth weight corrected for gestational age, mother's weight before pregnancy and weight gain in pregnancy, obtained from the Jerusalem perinatal study, and blood pressure and body mass index at age 17, available from military draft records.
Setting: Jerusalem, Israel.
Subjects: 10,883 subjects (6,684 men and 4,199 women) born in Jerusalem during 1974-6 and subsequently drafted to the army.
Main outcome measures: Systolic and diastolic blood pressures measured at age 17 and their correlation with birth weight, size at birth, mother's body mass index and weight gain during pregnancy, and height and weight at age 17.
Results: Systolic and diastolic blood pressures were significantly and positively correlated with body weight, height, body mass index at age 17, and with mother's body weight and body mass index before pregnancy, but not with birth weight or mother's weight gain in pregnancy.
Conclusion: Variables reflecting poor intrauterine nutrition, including low maternal body mass index before pregnancy, poor maternal weight gain in pregnancy, and being born small for gestational age, were not associated with a higher blood pressure in late adolescence.
Introduction
Several studies have shown a significant inverse relation between blood pressure and birth weight,(1-6) which may be a result of fetal adaptations to an adverse environment, particularly undernutrition.(7) Data showing a strong association between maternal nutritional status in pregnancy and blood pressure at 10-12 years of age support this contention,(8) and further confirmation comes from study of the influence of mother's diet in late pregnancy on their offspring's adult blood pressure.(9) However, not all investigators have confirmed this association.(10-13) In addition, the hypothesis that high blood pressure has early nutritional origins was not supported by a study assessing the effect of poor nutrition in infants born before term on later high blood pressure.(14)
Previous studies examining prenatal effects on blood pressure defined intrauterine growth retardation as birth weight below 2500 g.(15) A more accurate assessment of intrauterine growth is provided by size at birth considered in relation to gestational age, rather than birth weight alone. Also, in this study we assessed maternal nutritional status during pregnancy on the basis of body weight before pregnancy corrected for height and weight gain in pregnancy.
We aimed to evaluate the effects of being born small or large for gestational age, and of the mother's nutritional status, on systolic and diastolic blood pressure at 17 years of age. The large computerised dataset allowed adjustment for height and weight of the subjects and their mothers as well as for birth order, ethnic origin, and socioeconomic factors.
Subjects and methods
Data on 11,428 infants born between November 1974 and February 1976 were obtained from the computerised records of the Jerusalem study on oral contraceptive use,(16) one of the interlocking epidemiologic studies making up the Jerusalem perinatal study, the design and methods of which have been reported.(17) Variables included birth weight and gestational age recorded at the time of delivery, as well as detailed sociodemographic information. Socioeconomic status was assessed by area of residence (classified by municipal tax level areas(17)) and mother's educational attainment (years of schooling). Ethnic origin was defined according to father's country of birth. Gestational age was determined, in women with regular menstrual cycles,(18) according to the date of the last menstrual period acquired through individual interviews with all mothers on the day after delivery.(19) The perinatal data were matched to measurements made at age 17 obtained from the computerised records of the Israel defence forces' draft medical examination, using the subject's seven digit identification number assigned at the time of draft.(20) The adequacy of the match was confirmed by comparing sex and mother's identity number. Complete information on all variables was available on 10,883 (95.2%) of the subjects. Only 38.6% of our study population (4,201 subjects) were women, as women who declare themselves to be orthodox religious are exempted from military service.(20) We thus analysed and presented the results separately for men and women. Only a negligible minority (124, <2%) of male subjects (those in hospital because of severe chronic and psychiatric disease and long term prisoners) were not examined and consequently were excluded from the study.
Subjects' birth weights were stratified in fifths for gestational age, on the basis of growth curves determined for our entire study population, to avoid a bias that may be caused by use of growth curves developed for a different population.
Blood pressure was measured in the sitting position in the right arm with a Bauman sphygmomanometer with appropriate cuff size. The end point for diastolic blood pressure was the disappearance of the Korotkoff sounds (phase V). The examiners were not aware of the perinatal data. Standing height was measured without shoes to the nearest centimetre, and body weight without clothes was determined to the nearest 100 g.
Regression coefficients with 95% confidence intervals were calculated by multiple linear regression analysis (SAS Institute, Cary, NC) to control for the effects of the studied independent variables. The variables included in the regression model were birth weight corrected for gestational age, birth order, ethnic origin, social status, height and body mass index (kg/m2) at 17 years of age, and mother's educational attainment, body mass index, and weight gain in pregnancy.
| Table 1 - Correlation (Pearson coefficients) with systolic and diastolic blood pressure at age 17 of birth weight; weight, height, and body mass index at age 17; mother's weight and body mass index before pregnancy; and weight gain in pregnancy | ||||
| Women (n=4199) | Men (n=6692) | |||
|---|---|---|---|---|
| Systolic | Diastolic | Systolic | Diastolic | |
| Birth weight (g) | 0.011 | 0.009 | -0.009 | 0.003 |
| Body weight (kg) | 0.171*** | 0.135*** | 0.219*** | 0.158*** |
| Height (cm) | 0.081*** | 0.040* | 0.066* | 0.054*** |
| Body mass index (kg/m2) | 0.143*** | 0.125*** | 0.211*** | 0.149*** |
| Mother's weight before pregnancy (kg) | 0.084*** | 0.058*** | 0.075*** | 0.069*** |
| Mother's body mass index before pregnancy (kg/m2) | 0.053*** | 0.049** | 0.053*** | 0.060*** |
| Mother's weight gain in pregnancy (kg) | 0.019 | 0.018 | 0.002 | 0.001 |
| *P<0.01, **P<0.001, ***P<0.0001. | ||||
Results
Systolic and diastolic blood pressure at age 17 correlated significantly with body weight and height, body mass index, and mother's body weight and body mass index before pregnancy, but not with birth weight or mother's weight gain in pregnancy (table 1). After adjustment for birth weight, mother's body mass index, body weight at age 17, and ethnic origin by a multiple regression analysis model, systolic and diastolic blood pressure and body weight were positively associated (table 2). Birth weight and Western and Israeli ethnic origin were negatively associated with blood pressure (table 2). Birth order, social status, and mother's and father's educational attainment were not included in the final regression model as they did not influence blood pressure significantly.
| Table 2 - Mean regression coefficients (95% confidence interval) for systolic and diastolic blood pressure at age 17 | ||||
| Women (n=4199) | Men (n=6692) | |||
|---|---|---|---|---|
| Systolic | Diastolic | Systolic | Diastolic | |
| Birth weight (kg) | -0.73
(-1.51 to 0.05) | -0.27 (-0.82 to 0.28) | -0.94 (-1.54 to -0.33) | -0.31 (-0.73 to 0.11) |
| Body weight at age 17 (kg) | 0.19 (0.15 to 0.23) | 0.12 (0.09 to 0.15) | 0.24 (0.21 to 0.27) | 0.12 (0.10 to 0.14) |
| Mother's weight before pregnancy (kg) | 0.09 (-0.006 to 0.18) | 0.02 (-0.04 to 0.09) | 0.03 (-0.05 to 0.1) | -0.02 (-0.07 to 0.03) |
| Mother's body mass index (kg/m2) | -0.12 (-0.37 to 0.14) | 0.001 (-0.18 to 0.18) | -0.03 (-0.23 to 0.18) | 0.11 (-0.03 to 0.25) |
| Mother's weight gain (kg) | 0.02 (-0.06 to 0.11) | 0.02
(-0.03 to 0.08) | -0.03 (-0.09 to 0.04) | -0.01 (-0.06 to 0.04) |
| Western ethnic origin | -1.73 (-2.57 to -0.89) | -0.42 (-1.01 to 0.17) | -2.47 (-3.14 to -1.8) | -0.32 (-0.79 to 0.14) |
| Israeli ethnic origin | -0.9 (-1.73 to -0.06) | -0.02 (-0.61 to 0.57) | -0.94 (-1.65 to -0.24) | -0.01 (-0.50 to 0.47) |
The mean systolic and diastolic blood pressures increased with adolescent body mass index group in young women and young men (tables 3 and 4). The fifth of birth weight for gestational age was not associated the mean systolic or diastolic blood pressure at age 17 (tables 3 and 4). Adjustment for body weight at age 17 and mother's weight before pregnancy, body mass index, weight gain in pregnancy, and ethnic origin in a multiple regression model did not change these associations.
| Table 3 - Mean (SEM) blood pressure and corrected mean (95% confidence interval)* in women at age 17 by size at birth and body mass (lower 10th, intermediate categories, and upper 10th) | |||||
| Birth weight corrected for gestational age (fifth) | Body mass index (kg/m2) | ||||
|---|---|---|---|---|---|
| <17.6 * | 17.6-20.5 * | 20.6-25 * | >25 * | Total # | |
| Systolic blood pressure (mm Hg) | |||||
| 1 (up to 20th centile): | |||||
| Crude | 108.5 (1.1) (n=110) | 110.8 (0.6) (n=332) | 111.8 (0.7) (n=290) | 115.8 (1.2) (n=89) | 111.4 (0.4)
(n=821) |
| Corrected | 110.7 (108.5 to 113.0) | 112 (110.7 to 113.3) | 111.5 (110.2 to 112.9) | 112.7 (110.1 to 115.3) | 111.8 (0.4)
(n=111 to 112.6) |
| 2 (20th up to 40th centile): | |||||
| Crude | 109.6 (1.1) (n=116) | 110.3 (0.6)
(n=398) | 111.7 (0.6) (n=334) | 113 (1.2)
(n=84) | 110.9 (0.4) (n=932) |
| Corrected | 111.5 (109.3 to 113.7) | 111.4 (110.3 to 112.6) | 111.4 (110.2 to 112.7) | 110.3 (107.6 to 113.0) | 111.4
(110.6 to 112.1) |
| 3 (40th up to 60th centile): | |||||
| Crude | 109 (1.1) (n=97) | 111.6 (0.6)
(n=314) | 112.6 (0.6) (n=306) | 115.2 (1.3)
(n=76) | 112 (0.4) (n=793) |
| Corrected | 111.2 (108.8 to 113.6) | 112.6 (111.3 to 113.9) | 111.9 (110.6 to 113.2) | 112.1 (109.4 to 114.9) | 112.1
(111.3 to 112.9) |
| 4 (60th up to 80th centile): | |||||
| Crude | 106.5 (1.3) (n=78) | 109.3 (0.6)
(n=333) | 111.7 (0.6) (n=341) | 114.4 (1.3)
(n=88) | 110.5 (0.4) (n=840) |
| Corrected | 108.3 (105.7 to 110.9) | 109.7 (108.4 to 110.9) | 111 (109.8 to 112.3) | 111 (108.4 to 113.7) | 110.2 (109.4 to 111) |
| 5 (80th centile or higher): | |||||
| Crude | 108.5 (1.2) (n=89) | 110.7 (0.6)
(n=353) | 112.3 (0.6) (n=419) | 114.7 (1.0)
(n=130) | 111.7 (0.4) (n=991) |
| Corrected | 110.6 (108.0 to 113.1) | 111.4 (110.2 to 112.7) | 111.4 (110.3 to 112.6) | 110.8 (108.4 to 113.2) | 111.2
(110.5 to 112) |
| Diastolic blood pressure (mm Hg) | |||||
| 2 (up to 20th centile): | |||||
| Crude | 67.5 (0.9) (n=110) | 69.8 (0.4)
(n=332) | 70.4 (0.5) (n=290) | 72.9 (0.8)
(n=89) | 70 (0.3) (n=821) |
| Corrected | 68.6 (67.0 to 70.2) | 70.4
(69.5 to 71.3) | 70.3 (69.3 to 71.2) | 71.1
(69.3 to 73.0) | 70.2 (69.6 to 70.8) |
| 2 (20th up to 40th centile): | |||||
| Crude | 69.9 (0.8)
(n=116) | 70 (0.4) (n=398) | 71.3 (0.4)
(n=334) | 71.5 (0.8) (n=84) | 70.6 (0.3)
(n=932) |
| Corrected | 70.6 (69.0 to 72.1) | 70.6 (69.7 to 71.4) | 71.1 (70.3 to 72.0) | 70 (68.1 to 71.9) | 70.7 (70.2 to 71.3) |
| 3 (40th up to 60th centile): | |||||
| Crude | 69.3 (0.8) (n=97) | 70.2 (0.4)
(n=314) | 70.7 (0.5) (n=306) | 71.1 (0.9)
(n=76) | 70.4 (0.3) (n=793) |
| Corrected | 70.5 (68.8 to 72.2) | 70.7
(69.8 to 71.6) | 70.3 (69.4 71.3) | 69.5 (67.5 to 71.4) | 70.4 (69.9 to 71.0) |
| 4 (60th up to 80th centile): | |||||
| Crude | 68.1 (0.9)
(n=78) | 69.3 (0.4) (n=333) | 70.7 (0.4)
(n=341) | 73.2 (0.9) (n=88) | 70.2 (0.3)
(n=840) |
| Corrected | 69.1 (67.3 to 70.9) | 69.6 (68.7 to 70.5) | 70.3 (69.4 to 71.2) | 71.5 (69.6 to 73.3) | 70 (69.5 to 70.6) |
| 5 (80th centile or higher): | |||||
| Crude | 68.3 (0.8) (n=89) | 69.5 (0.4)
(n=353) | 70.8 (0.4) (n=419) | 72.5 (0.7)
(n=130) | 70.3 (0.3) (n=991) |
| Corrected | 69.2 (67.4 to 71.0) | 69.9
(69.0 to 70.8) | 70.4 (69.6 to 71.3) | 70.8
(69.1 to 72.5) | 70.2 (69.6 to 70.7) |
| *For corrected mean (95% CI) for categories of body mass index, the model included body weight at age 17 and mother's weight before pregnancy, body mass index before pregnancy, weight gain, and ethnic origin of the father, and a discrete variable with different levels for all 15 combinations of fifths of birth weight corrected for gestational age and four body mass index categories. For total population, the model included body weight at age 17 and mother's weight before pregnancy, body mass index before pregnancy, weight gain, and ethnic origin, and a discrete variable with different levels for fifths of birth weight corrected for gestational age. | |||||
| Table 4 - Mean (SEM) blood pressure and corrected mean (95% confidence interval)* in men at age 17 by size at birth and body mass (lower 10th, intermediate categories, and upper 10th) | |||||
| Birth weight corrected for gestational age(fifth) | Body mass index (kg/m2) | ||||
|---|---|---|---|---|---|
| <18.1 | 18.1-21.1 | 21.2-25.5 | >25.5 | Total | |
| Systolic blood pressure (mm Hg) | |||||
| 1 (up to 20th centile): | |||||
| Crude | 116.2 (0.8)
(n=157) | 116.9 (0.5) (n=605) | 119.2 (0.5)
(n=510) | 123.2 (1.1) (n=128) | 118.2 (0.3)
(n=1400) |
| Corrected | 118.6 (116.6 to 120.6) | 118.2 (117.2 to 119.2) | 118.8 (117.8 to 119.9) | 120 (117.8 to 122.2) | 118.7 (118.1 to 119.4) |
| 2 (20th up to 40th centile): | |||||
| Crude | 114.2 (1.0) (n=129) | 117 (0.5)
(n=550) | 119.5 (0.5) (n=515) | 124.9 (0.9)
(n=157) | 118.6 (0.3) (n=1351) |
| Corrected | 116.3 (114.2 to 118.4) | 118.2 (117.2 to 119.3) | 119.1 (118.1 to 120.1) | 121.6 (119.6 to 123.7) | 118.8
(118.2 to 119.4) |
| 3 (40th up to 60th centile): | |||||
| Crude | 116.1 (1.4) (n=123) | 117.1 (0.5)
(n=519) | 120.5 (0.5) (n=535) | 122.2 (1)
(n=144) | 118.9 (0.3) (n=1321) |
| Corrected | 118.2 (116 to 120.4) | 118
(116.9 to 119.1) | 119.7 (118.7 to 120.7) | 118.7 (116.6 to 120.8) | 118.8 (118.2 to 119.4) |
| 4 (60th up to 80th centile): | |||||
| Crude | 112.9 (1.1) (n=105) | 116.5 (0.5)
(n=506) | 118.4 (0.5) (n=547) | 125 (1)
(n=161) | 118 (0.3) (n=1319) |
| Corrected | 115.1 (112.7 to 117.4) | 117.6 (116.6 to 118.7) | 118 (117 to 119) | 121.1 (119 to 123.1) | 117.9 (117.3 to 118.6) |
| 5 (80th centile or higher): | |||||
| Crude | 114.8 (1.1) (n=117) | 116 (0.5)
(n=559) | 119.3 (0.4) (n=739) | 122.8 (0.7)
(n=226) | 118.3 (0.3) (n=1985) |
| Corrected | 116.8 (114.5 to 119.1) | 116.8 (115.7 to 117.8) | 118.5 (117.6 to 119.4) | 118.3 (116.4 to 120.3) | 117.7
(117.1 to 118.3) |
| Diastolic blood pressure (mm Hg) | |||||
| 1 (up to 20th centile): | |||||
| Crude | 71.4 (0.6) (n=157) | 72 (0.3)
(n=605) | 73.1 (0.4) (n=510) | 74.8 (0.8)
(n=128) | 72.6 (0.2) (n=1400) |
| Corrected | 72.7 (71.4 to 74.1) | 72.7
(72 to 73.4) | 72.8 (72.1 to 73.5) | 73 (71.5 to 74.5) | 72.8 (72.4 to 73.3) |
| 2 (20th up to 40th centile): | |||||
| Crude | 71 (0.7)
(n=129) | 72.6 (0.3) (n=550) | 73.5 (0.3)
(n=515) | 75.3 (0.6) (n=157) | 73.1 (0.2)
(n=1351) |
| Corrected | 72.1 (70.7 to 73.6) | 73.2 (72.4 to 73.9) | 73.1 (72.4 to 73.8) | 73.5 (72.1 to 74.9) | 73.1 (0.2) (n=72.7 to 73.5) |
| 3 (40th up to 60th centile): | |||||
| Crude | 70 (0.8) (n=123) | 71.8 (0.4)
(n=519) | 73.4 (0.3) (n=535) | 74.4 (0.7)
(n=144) | 72.6 (0.2) (n=1321) |
| Corrected | 70.9 (69.4 to 72.4) | 72.1
(71.4 to 72.8) | 73.1 (72.4 to 73.8) | 72.5
(0.8) (n=71 to 73.9) | 72.4 (0.2) (n=72 to 72.9) |
| 4 (60th up to 80th centile): | |||||
| Crude | 70.9 (0.8) (n=105) | 71.8 (0.3)
(n=506) | 72.6 (0.3) (n=547) | 76 (0.6)
(n=161) | 72.6 (0.2) (n=1319) |
| Corrected | 72.2 (70.6 to 73.8) | 72.3
(71.6 to 73.1) | 72.2 (71.5 to 72.9) | 74 (72.5 to 75.4) | 72.4 (72 to 72.9) |
| 5 (80th centile or higher): | |||||
| Crude | 70.8 (0.8)
(n=117) | 71.6 (0.3) (n=559) | 73.6 (0.3)
(n=739) | 75 (0.5) (n=226) | 72.9 (0.2)
(n=1641) |
| Corrected | 71.5 (69.9 to 73.1) | 72 (71.3 to 72.7) | 73.4 (72.7 to 74) | 73.1 (71.7 to 74.4) | 72.7 (72.3 to 73.1) |
| *For corrected mean (95% CI) for categories of body mass index, the model included body weight at age 17 and mother's weight before pregnancy, body mass index before pregnancy, weight gain, and ethnic origin of the father, and a discrete variable with different levels for all 15 combinations of fifths of birth weight corrected for gestational age and four body mass index categories. For total population, the model included body weight at age 17 and mother's weight before pregnancy, body mass index before pregnancy, weight gain, and ethnic origin, and a discrete variable with different levels for fifths of birth weight corrected for gestational age. | |||||
| Table 5 - Mean (SEM) and corrected mean (95% confidence interval)* blood pressure in women at age 17 by mother' s body mass index before pregnancy and weight gain in pregnancy | ||||||
| Weight gain in pregnancy (fifths) | Mother's body mass index (kg/m2) | |||||
| 19.3 | 19.53 - 20.96 | 20.96 - 22.35 | 22.35 - 24.24 | greater than 24.24 | Total | |
| Systolic blood pressure (mm Hg) | ||||||
| 1 (8 kg and under): | ||||||
| Crude | 110.5 (1) (n=146) | 111.3 (0.9) (n=152) | 110.4 (0.9) (n=166) | 110.9 (0.9) (n=186) | 113 (0.7) (n=234) | 111.5 (0.4) (n=919) |
| Corrected | 111.4 (109.5 to 113.4) | 111.6 (109.7 to 113.4) | 110.3 (108.6 to 112) | 110.8 (109.2 to 112.4) | 112.4 (110.7 to 114.1) | 111.4 (110.6 to 112.1) |
| 2 (8-10 kg): | ||||||
| Crude | 109.6 (0.8) (n=181) | 110.1 (0.8) (n=188) | 111.2 (0.8) (n=179) | 111.4 (0.9) (n=167) | 112.6 (0.9) (n=139) | 110.9 (0.4) (n=869) |
| Corrected | 110.4 (108.7 to 112.1) | 110.3 (108.7 to 112) | 111.3 (109.7 to 113) | 111.3 (109.6 to 113.1) | 111.8 (109.7 to 113.8) | 111 (110.2 to 111.8) |
| 3 (10-12 kg): | ||||||
| Crude | 109.4 (0.8) (n=200) | 111.5 (0.8) (n=207) | 113.2 (0.9) (n=160) | 111.3 (0.9) (n=144) | 112.6 (1.1) (n=122) | 111.4 (0.4) (n=844) |
| Corrected | 110.3 (108.6 to 112) | 112 (110.5 to 113.6) | 113 (111.2 to 114.7) | 111 (109.2 to 112.9) | 111.7 (109.5 to 113.9) | 111.6 (110.8 to 112.4) |
| 4 (12-15 kg): | ||||||
| Crude | 109.9 (0.8) (n=201) | 112.2 (0.8) (n=207) | 109.5 (0.8) (n=184) | 112 (0.9) (n=161) | 111.5 (1) (n=124) | 111 (0.4) (n=892) |
| Corrected | 110.5 (108.9 to 112.2) | 112.6 (111.1 to 114.2) | 109.7 (108.1 to 111.4) | 111.4 (109.7 to 113.2) | 110.3 (108.2 to 112.5) | 111 (110.2 to 111.7) |
| 5 (>15 kg): | ||||||
| Crude | 111.9 (0.9) (n=168) | 112.7 (1) (n=153) | 111.6 (0.9) (n=153) | 111.4 (1.0) (n=145) | 113.5 (1.1) (n=88) | 112.1 (0.4) (n=715) |
| Corrected | 112.4 (110.6 to 114.2) | 112.6 (110.8 to 114.4) | 111.1 (109.3 to 112.9) | 110.8 (108.9 to 112.6) | 112.3 (109.7 to 114.8) | 111.8 (110.9 to 112.6) |
| Diastolic blood pressure (mm Hg) | ||||||
| 1 (8 kg and under): | ||||||
| Crude | 68.7 (0.6) (n=146) | 69.8 (0.7) (n=152) | 70.4 (0.6) (n=166) | 70.4 (0.6) (n=186) | 71.5 (0.5) (n=234) | 70.4 (0.3) (n=919) |
| Corrected | 69.2 (67.8 to 70.6) | 70 (68.7 to 71.3) | 70.4 (69.2 to 71.6) | 70.3 (69.2 to 71.5) | 71.1 (69.9 to 72.3) | 70.3 (69.7 to 70.8) |
| 2 (8-10 kg): | ||||||
| Crude | 70.1 (0.6) (n=181) | 69.7 (0.6) (n=188) | 71 (0.6) (n=179) | 70.1 (0.6) (n=167) | 71.4 (0.6) (n=139) | 70.3 (0.3) (n=869) |
| Corrected | 70.5 (69.3 to 71.8) | 69.8 (68.7 to 71) | 71 (69.9 to 72.2) | 70.1 (68.8 to 71.3) | 70.9 (69.5 to 72.4) | 70.5 (69.9 to 71) |
| 3 (10-12 kg): | ||||||
| Crude | 69.2 (0.6) (n=200) | 69.7 (0.6) (n=207) | 70.5 (0.7) (n=160) | 69.7 (0.7) (n=144) | 70.9 (0.7) (n=122) | 69.9 (0.3) (n=844) |
| Corrected | 69.7 (68.5 to 70.8) | 70 (68.9 to 71.1) | 70.3 (69.1 to 71.6) | 69.6 (68.3 to 70.9) | 70.4 (68.8 to 72) | 70 (69.4 to 70.5) |
| 4 (12-15 kg): | ||||||
| Crude | 69.9 (0.6) (n=201) | 70.5 (0.5) (n=207) | 69.9 (0.6) (n=184) | 71.1 (0.6) (n=161) | 69.8 (0.7) (n=124) | 70.2 (0.3) (n=892) |
| Corrected | 70.3 (69.1 to 71.5) | 70.7 (69.6 to 71.8) | 70 (68.9 to 71.2) | 70.8 (69.6 to 72.1) | 69.2 (67.7 to 70.7) | 70.3 (69.8 to 70.8) |
| 5 (>15 kg): | ||||||
| Crude | 70.9 (0.6) (n=168) | 71.2 (0.7) (n=153) | 70.2 (0.6) (n=153) | 70.2 (0.7) (n=145) | 71.8 (0.8) (n=88) | 70.8 (0.3) (n=715) |
| Corrected | 71.1 (69.9 to 72.4) | 71.2 (69.9 to 72.4) | 69.9 (68.7 to 71.2) | 69.9 (68.6 to 71.2) | 71.0 (69.2 to 72.8) | 70.6 (70.0 to 71.2) |
| *For corrected means (95% confidence intervals) the model included body weight, mother's weight before pregnancy, birth weight, body mass index, ethnic origin of the father, and a discrete variable with different levels for all 25 combinations of mother's body mass index and mother's weight gain in pregnancy categories, the least squares means for this variable are brought in the central part of the table. For total population, the model included body weight, maternal prepregnant weight, maternal body mass index, ethnic origin, body mass index, birth weight, and a mother's weight before pregnancy, birth weight, body mass index, ethnic origin, and a discrete variable for mother's weight gain in pregnancy | ||||||
| Table 6 | ||||||
| Mean (SEM) and corrected mean (95% confidence interval)* blood pressure in men at age 17 by mother's body mass index before pregnancy and weight gain in pregnancy | ||||||
| Weight gain in pregnancy | ||||||
| less than 19.53 | 19.53-20.96 | 20.96-22.35 | 22.35-24.24 | greater than 24.24 | Total | |
| Systolic blood pressure (mm Hg) | ||||||
| (equal or less than 8 kg): | ||||||
| Crude | 116.6 (0.8) (n=244) | 119.5 (0.9) (n=269) | 119.4 (0.6) (n=291) | 118.8 (0.6) (n=325) | 119.2 (0.6) (n=413) | 118.8 (0.3) (n=1595) |
| Corrected | 117.5 (116.0 to 119.0) | 119.7 (0.7) (118.3 to 121.1) | .5 (0.7) (118.2 to 120.8) | 119 (0.6) (117.7 to 120.3) | 118.5 (0.7) (117.2 to 119.9) | 118.9 (0.3) (118.3 to 119.5) |
|
2 (8-10 kg) |
||||||
| Crude | 116.6(0.7) (n=314) | 120.6 (0.7) (n=279) | 117.6 (0.7) (n=285) | 119 (0.7) (n=261) | 118.8 (0.7) (n=244) | 118.5 (0.3) (n=1431) |
| Corrected | 117.4 (0.7) (116.1 to 118.8) | 120.7 (0.7) (119.3 to 122) | 117.7 (0.7) (116.3 to 119) | 118.8 (0.7) (117.4 to 120.2) | 118 (116.4 to 119.6) | 118.5 (0.3) (117.9 to 119.1) |
|
3 (10-12 kg) |
||||||
| Crude | 116.8 (0.7) (n=269) | 116.4 (0.7) (n=252) | 117.5 (0.7) (n=271) | 119 (0.8) (n=227) | 119.5 (0.8) (n=198) | 117.8 (0.3) (n=1245) |
| Corrected | 117.7 (0.7) (116.2 to 119.2) | 116.9 (0.7) (115.5 to 118.4) | 17.7 (0.7) (116.3 to 119) | 118.9 (0.8) (117.4 to 120.4) | 118.7 (0.9) (117 to 120.5) | 117.9 (0.3) (117.3 to 118.6) |
|
4 (12-15 kg) |
||||||
| Crude | 117.3 (0.6) (n=317) | 117.4 (0.6) (n=306) | 119 (0.7) (n=273) | 119 (0.7) (n=263) | 119.4 (0.8) (n=197) | 118.3 (0.3) (n=1375) |
| Corrected | 118.3 (0.7) (117 to 119.7) | 117.5 (0.7) (116.2 to 118.8) | 118.4 (0.7) (117 to 119.8) | 118.7 (0.7) (117.3 to 120.1) | 118.2 (0.9) (116.5 to 120) | 118.2 (0.3) (117.6 to 118.8) |
|
5 (greater than 15kg) |
||||||
| Crude | 118 (0.8) (n=269) | 117.9 (0.8) (n=198) | 119.2 (0.8) (n=205) | 119.2 (0.8) (n=200) | 118.4 (1) (n=162) | 118.5 (0.4) (n=1047) |
| Corrected | 118.5 (0.7) (117.1 to 120) | 118.1 (0.8) (116.4 to 119.7) | 118.6 (0.8) (117 to 120.2) | 118.2 (0.8) (116.6 to 119.8) | 117.4 (1) (115.5 to 119.3) | 118.2 (0.4) (117.5 to 118.9) |
| Diastolic blood pressure (mm Hg) |
||||||
| 1 (equal or less than 8 kg) | ||||||
| Crude | 72 (0.5) (n=244) | 72.4 (0.5) (n=269) | 73.6 (0.4) (n=291) | 72.9 (0.4) (n=325) | 73.1 (0.4) (n=413) | 72.9 (0.2) (n=1595) |
| Corrected | 72.4 (0.5) (71.4 to 73.5) | 72.5 (0.5) (71.6 to 73.5) | 73.7 (0.5) (72.8 to 74.6) | 73.1 (0.4) (72.2 to 73.9) | 72.8 (0.5) (71.9 to 73.7) | 72.9 (0.2) (72.5 to 73.3) |
|
2 (8-10 kg) |
||||||
| Crude | 71.8 (0.5) (n=314) | 72.9 (0.5) (n=279) | 72.1 (0.5) (n=285) | 73.2 (0.5) (n=261) | 73.6 (0.5) (n=244) | 72.7 (0.2) (n=1431) |
| Corrected | 72.3 (0.5) (71.3 to 73.2) | 73 (0.5) (72 to 73.9) | 72.2 (0.5) (71.3 to 73.1) | 73.1 (0.5) (72.1 to 74.1) | 73.3 (0.6) (72.2 to 74.5) | 72.7 (0.2) (72.3 to 73.2) |
|
3 (10-12 kg) |
||||||
| Crude | 71.9 (0.5) (n=269) | 71.6 (0.5) (n=252) | 72.2 (0.5) (n=271) | 73.6 (0.5) (n=227) | 73.9 (0.6) (n=198) | 72.6 (0.2) (n=1245) |
| Corrected | 72.2 (0.5) (71.2 to 73.3) | 71.8 (0.5) (70.8 to 72.8) | 72.3 (0.5) (71.4 to 73.3) | 73.6 (0.5) (72.5 to 74.6) | 73.6 (0.6) (72.4 to 74.8) | 72.7 (0.2) (72.2 to 73.1) |
|
4 (12-15 kg): |
||||||
| Crude | 71.9 (0.5) (n=317) | 71.8 (0.4) (n=306) | 74.1 (0.5) (n=273) | 72.8 (0.5) (n=263) | 73.2 (0.6) (n=197) | 72.7 (0.2) (n=1375) |
| Corrected | 72.3 (0.5) (71.4 to 73.3) | 71.8 (0.5) (70.9 to 72.7) | 73.8 (0.5) (72.8 to 74.8) | 72.7 (0.5) (71.7 to 73.6) | 72.7 (0.6) (71.5 to 73.9) | 72.7 (0.2) (72.2 to 73.1) |
|
5 (greater than15 kg) |
||||||
| Crude | 72.3 (0.5) (n=269) | 72.6 (0.6) (n=198) | 73 (0.6) (n=205) | 72.2 (0.6) (n=200) | 73.4 (0.7) (n=162) | 72.7 (0.3) (n=1047) |
| Corrected | 72.4 (0.5) (71.4 to 73.5) | 72.6 (0.6) (71.5 to 73.8) | 72.7 (0.6) (71.6 to 73.8) | 71.7 (0.6) (70.6 to 72.8) | 73 (0.7) (71.7 to 74.3) | 72.5 (0.3) (72 to 73) |
| *For corrected means (95% confidence intervals) the model included body weight, mother's weight before regnancy, birth weight, body mass index, ethnic origin, and a discrete variable with different levels for all 25 combinations of mother's body mass index and mother's weight gain in pregnancy categories, the least squares means for this variable are brought in the central part of the table. For total population, the model included body weight, maternal prepregnant weight, maternal BMI, ethnic origin, BMI, birth weight, and a mother's weight before regnancy, birth weight, body mass index, ethnic origin, and a discrete variable for mother's weight gain in pregnancy | ||||||
After adjustment for the above variables, mother's body mass index was positively associated with blood pressure while weight gain in pregnancy had little influence on blood pressure at age 17 (see tables 5 and 6). Furthermore, subjects born to women with low body mass index before pregnancy, or those who gained little weight in pregnancy, did not have a higher mean systolic or diastolic blood pressure.
Discussion
Adverse intrauterine conditions, suggested by small size for gestational age, were not associated with high blood pressure at age 17. Birth weight was positively, rather than negatively, correlated with blood pressure. This finding is in agreement with our previous study on 33,545 subjects born a decade earlier, in which low birth weight was poorly correlated with blood pressure in late adolescence.(10) The present study has an advantage over the previous series, because an accurate estimation of gestational age was available, better reflecting intrauterine growth than birth weight alone. More importantly, maternal nutritional status during pregnancy could be assessed, and low weight and body mass index before pregnancy, as well as poor weight gain in pregnancy, were not associated with high blood pressure. In fact, the mother's body mass index before pregnancy and weight gain in pregnancy had an independent positive effect on blood pressure at 17 years of age.
Conflicting findings
Since we first reported, in 1991, that intrauterine environment,
as shown by birth weight, has little effect on blood pressure in 17
year old subjects,(10) additional studies have confirmed our
observation in 15, 16, and 18 year olds.(11-13) The weak
association between birth weight and blood pressure in teenagers has
subsequently been attributed to perturbation of blood pressure tracking
during this period of rapid growth,(7) but subjects who are
17 and 18 years old are probably well past the pubertal growth spurt.
Law et al noted that babies who are small at birth, and not just premature, tend to have raised blood pressure during adult life.(3) In contrast to the previous four studies assessing birth weight in adolescence,(10-13) in the present study we were able to determine the appropriateness of size at birth in relation to the gestational age. We were also able to correct for multiple confounding factors such as body mass index and mother's body mass index, socioeconomic status, and ethnic origin. Even so, our findings do not support an inverse relationship between size at birth and blood pressure. In a previous study that found an inverse association in children 5 to 7 years of age, social class, educational attainment and mother's body mass index corrected for the child's body mass index were not related to blood pressure.(21)
The finding that girls born large for gestational age have a higher incidence of raised systolic blood pressure at age 17 may be a chance finding due to analysis of multiple subgroups. Laurer et al, though, have found that children with a high birth weight had higher blood pressure up to the age of 4 years(4); conversely, Whincup et al found an inverse relation between birth weight and blood pressure, especially prominent in girls.(5)
We found a strong positive association between body mass index and blood pressure, as observed in many other populations.(22) However, subjects who were small at birth and became overweight were not at higher risk of high blood pressure, as has recently been suggested.(23)
Limitations
Our study was limited by several factors. Firstly, as length at
birth was not recorded, we were unable to calculate the body mass index
at birth. A previous study using this body mass index at birth to
determine symmetrical (light and short) and asymmetrical (light and of
normal length) delayed intrauterine growth did not find an association
with systolic or diastolic blood pressure at age18 years.(9)
Secondly, we did not obtain placental weights. This factor has been
found to be strongly related to systolic and diastolic blood pressure
in adults,(2) but a recent study showed that birth weight,
rather than placental ratio (ratio of placental weight to birth
weight), is the early life factor most importantly related to blood
pressure in childhood.(5)
Use of body mass index
Godfrey et al found a link between maternal triceps skinfold
thickness and the blood pressure in 77 children at 10-12 years of
age.(8) They speculated that fetal undernutrition may lead
to adaptive changes, with long term consequences that initiate higher
blood pressure. We did not find that the mother's low body mass index
and poor weight gain in pregnancy was associated with a higher mean
systolic or diastolic blood pressure at late adolescence. Body mass
index may be a less accurate measure of nutritional status than
skinfold thickness. However, maternal body mass index and weight gain
in pregnancy are positively and significantly associated with birth
weight.(24) Furthermore, a recent longitudinal study showed
that in non-obese women the correlation between body mass index and
percentage of body fat remains during pregnancy.(25) In
addition, our results are based on a much larger population and a
longer follow up period. Therefore, it seems that the hypothesis that
the initiating effect of adult high blood pressure is fetal nutrition
in utero still demands more epidemiological
evidence.(26)
| Key Messages | ||||||||||||
|
Funding: None.
(Accepted 19 May 1997)
Conflict of interest: None
Department of Internal Medicine,
Carmel
Hospital,
Haifa,
Israel
Arie Laor, lecturer
Department of Pediatrics,
Stanford
University School of Medicine,
Stanford,
California,
USA
David
K Stevenson, professor
Department
of Internal Medicine,
Sheba Medical Center,
Sackler School of Medicine,
Tel-Aviv University,
Tel-Hashomer,
Israel
Jeoshua Shemer, senior lecturer
Department of Neonatology,
Bikur Cholim Hospital,
Jerusalem,
Israel
Rena Gale,
associate professor
Department of
Obstetrics and Gynecology,
Sheba Medical Center
Daniel S
Seidman, senior
physician
Correspondence to: Dr Seidman.
Reference
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