Size at birth and blood pressure at 3 years of age. The Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC)

The relations between size at birth and blood pressure were examined in a population-based longitudinal study of pregnancy and childbirth in the English county of Avon (the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC)) in 1994-1996. A total of 1,860 singleton children aged 3 years (response rate = 74%) were studied. Both height and body mass index were strongly related to blood pressure. After adjustment for current height and body mass index, birth weight showed a graded inverse relation with both systolic (-1.91 mmHg/kg, 95% CI -2.61 to -1.21 mmHg/kg, p < 0.0001) and diastolic blood pressure (-1.42 mmHg/kg, 95% CI -1.96 to -0.88 mmHg/kg, p < 0.0001) which was similar in boys and girls. Although birth length, head circumference, and ponderal index at birth were also inversely related to blood pressure, these relations disappeared after adjustment for birth weight. The strength of the birth weight-blood pressure relation was not strongly influenced by maternal height or by weight gain in the first year after birth, but was particularly strong in children who were shortest at 3 years of age. While the association between birth weight and blood pressure is consistent with reports from many earlier studies, the absence of independent relations between other measures of size at birth (particularly length:head circumference and ponderal index) and blood pressure does not suggest that undernutrition at a critical period of fetal growth plays an important role. Moreover, accelerated postnatal growth does not seem to underlie the birth weight-blood pressure association.     

Body size at birth and blood pressure among children in developing countries

BACKGROUND: Studies in developed countries have shown that reduced fetal growth is related to raised blood pressure in childhood and adult life. Little is known about this association in developing countries, where fetal growth retardation is common. METHODS: In 1994-1995, we measured blood pressure in 1570 3-6-year-old children living in China, Guatemala, Chile, Nigeria and Sweden. We related their blood pressure to patterns of fetal growth, as measured by body proportions at birth. The children were all born after 37 weeks gestation and weighed more than 2.5 kg at birth. RESULTS: In each country, blood pressure was positively related to the child's current weight. After adjusting for this and gender, systolic pressure was inversely related to size at birth in all countries except Nigeria. In Chile, China and Guatemala, children who were proportionately small at birth had raised systolic pressure. For example, in Chile, systolic pressure adjusted for current weight increased by 4.9 mmHg (95% CI : 2.1, 7.7) for every kilogram decrease in birthweight, by 1 mmHg (95% CI : 0.4, 1.6) for every centimetre decrease in birth length, and by 1.3 mmHg (95% CI : 0.4, 2.2) for every centimetre decrease in head circumference at birth. In Sweden, systolic pressure was higher in children who were disproportionately small, that is thin, at birth. Systolic pressure increased by 0.3 mmHg (95% CI : 0.0, 0.6) for every unit (kg/m3) decrease in ponderal index at birth. These associations were independent of the duration of gestation. CONCLUSIONS: Raised blood pressure among children in three samples from China, Central and South America is related to proportionate reduction in body size at birth, which results from reduced growth throughout gestation. The relation between fetal growth and blood pressure may be different in African populations. Proportionately reduced fetal growth is the prevalent pattern of fetal growth retardation in developing countries, and is associated with chronic undernutrition among women. Improvement in the nutrition and health of girls and young women may be important in preventing cardiovascular disease in developing countries.     

Exposure to famine during gestation, size at birth, and blood pressure at age 59 y: evidence from the dutch famine

We compared blood pressure of individuals (mean age 59 y) born in western Holland between January 1945 and March 1946 (mothers exposed to the Dutch Famine before or during gestation; n = 359) to blood pressure of unexposed individuals born before or conceived after the famine (n = 299) or same-sex siblings of subjects in series 1 or 2 (n = 313). Mean (SD) systolic and diastolic blood pressure were 140.3 (20.3) and 85.8 (11.0) mmHg, respectively; prevalence of hypertension (prior diagnosis of hypertension or with measured systolic/diastolic blood pressure above 140/90 mmHg) was 61.8%. Birth weight was inversely related to systolic (−4.14 mmHg per kg; 95% confidence interval (CI) −7.24, −1.03; p < 0.01) and diastolic (−2.09 mmHg per kg; 95% CI −3.77, −0.41; p < 0.05) blood pressure and to the prevalence of hypertension (odds ratio 0.67 per kg, 95% CI: 0.49, 0.93) (all age- and sex-adjusted). Any famine exposure of at least 10 weeks duration was associated with elevated systolic (2.77 mmHg; 95% CI 0.25, 5.30; p < 0.05) and diastolic (1.27 mmHg; 95% CI −0.13, 2.66; p = 0.08) blood pressure and with hypertension prevalence (odds ratio 1.44; 95% CI 1.04, 2.00; p < 0.05) in age- and sex-adjusted models. Exposure to famine during gestation may predispose to the development of hypertension in middle age.     

Effectiveness of lifestyle modification programs for control of blood pressure: a non-randomized controlled trial in Komatsu, Japan

PURPOSE: A non-randomized controlled trial was conducted to evaluate the effectiveness of three lifestyle modification programs to reduce blood pressure: individual counseling only; counseling using group dynamics; and individual support using mail. METHODS: We enrolled men and women ages 20-69 with a systolic blood pressure (SBP) of 130-159 mmHg and/or a diastolic blood pressure of 85-99 mmHg (high-normal or mild hypertension). Participants were assigned to one of 4 groups: individual counseling (n = 134); group counseling (n = 79); mailing support (n = 127); and controls (with usual care) (n = 178). The three intervention programs included behavioral support for each person's lifestyle problems once a month for 6 months. Sex and age adjusted net blood pressure change (and 95% confidence intervals [CIs]) compared with the control group was calculated for each of the intervention groups. RESULTS: Net SBP change was the largest for the group counseling group: sex and age adjusted net SBP change was -6.5 mmHg (95% CI: -10.0, -3.0). Net SBP change for the mailing support group was also significant (-4.3 mmHg [95% CI: -7.3, -1.3]). Net SBP change for the individual counseling group was -2.5 mmHg (95% CI: -5.5, 0.5). Looking at the results separately by sex, net SBP reduction was also largest in women of the group counseling group, whereas improvement in men was similar among 3 groups (approximately 4 mmHg). Body weights were reduced by about 1 kg in all 3 groups. CONCLUSIONS: Lifestyle modification programs using group dynamics or using individual support by mail, in addition to individual behavioral support, appear to be effective for blood pressure reduction. Group counseling may be more effective in women.     

The role of genetic and environmental factors in the association between birthweight and blood pressure: evidence from meta-analysis of twin studies

BACKGROUND: An inverse association between birthweight and later blood pressure has been found in many studies in singletons. Twin studies have been used to examine whether genetic factors or family environment could account for this association. METHODS: A systematic review identified 10 studies covering 3901 twin pairs. Meta-analysis of regression coefficients for the association between birthweight and systolic blood pressure was carried out for unpaired versus paired associations and for paired associations in dizygotic versus monozygotic pairs. RESULTS: After adjustment for current weight or body mass index (BMI), the difference in systolic blood pressure per kg birthweight was -2.0 (95% CI: -3.2, -0.8) mmHg in the unpaired analysis and -0.4 (95% CI: -1.5, 0.7) mmHg in the paired analysis in the same subjects. In the paired analysis by zygosity, in all twins the coefficients were -0.7 (95% CI: -2.3, 0.8) mmHg in dizygotic pairs and -0.8 (95% CI: -2.1, 0.4) mmHg in monozygotic pairs, but in studies which included zygosity tests the coefficients were -1.0 (95% CI: -3.3, 1.6) mmHg in dizygotic pairs and -0.4 (95% CI: -1.9, 1.3) mmHg in monozygotic pairs. CONCLUSIONS: The attenuation of the regression coefficient in the paired analysis provides support for the possibility that factors shared by twins contribute to the association between birthweight and blood pressure in singletons. Comparison of paired analysis in monozygotic and dizygotic pairs could not provide conclusive evidence for a role for genetic as opposed to shared environmental factors.     

Increased blood pressure in adolescents who were small for gestational age at birth: a cohort study in Brazil.

BACKGROUND: This paper studies the relationship between birthweight for gestational age and blood pressure in adolescents aged 14-15 years in southern Brazil. METHODS: A sample of 1076 adolescents belonging to a cohort of over 6000 children born in 1982 in Pelotas, southern Brazil, was studied in 1997. All households in a sample of 25% of the city's census tracts were visited and all adolescents born in 1982 were interviewed, weighed, and their blood pressures were measured twice. Data from the adolescents were linked to the database through their names and dates of births. RESULTS: High diastolic and systolic pressure (defined as >95th percentile) were significantly more frequent among adolescents who were born below the 10th percentile of birthweight for gestational age. No association was found between high blood pressure and low birthweight or preterm births. In a multiple linear regression analysis, the association between birthweight for gestational age and blood pressure was not statistically significant after adjusting for age, sex, skin colour and family income. However, when the current body mass index and height were added to the model both diastolic and systolic pressure were significantly associated with birthweight for gestational age, and adolescents who were small for gestational age at birth presented a mean elevation of 3.08 mmHg for diastolic pressure and 2.89 mmHg for systolic pressure. CONCLUSIONS: There is an inverse association between birthweight for gestational age and blood pressure during adolescence. This association, however, is only disclosed when the negative confounding effect of the body mass index is controlled for. The same association is not found when the effects of birthweight and gestational age on blood pressure are analysed separately. It appears therefore that the elevation of blood pressure during adolescence only occurs when there was intra-uterine growth retardation.     

The impact of parity on life course blood pressure trajectories: the HUNT study in Norway

The drop in blood pressure during pregnancy may persist postpartum, but the impact of pregnancy on blood pressure across the life course is not known. In this study we examined blood pressure trajectories for women in the years preceding and following pregnancy and compared life course trajectories of blood pressure for parous and nulliparous women. We linked information on all women who participated in the population-based, longitudinal HUNT Study, Norway with pregnancy information from the Medical Birth Registry of Norway. A total of 23,438 women were included with up to 3 blood pressure measurements per woman. Blood pressure trajectories were compared using a mixed effects linear spline model. Before first pregnancy, women who later gave birth had similar mean blood pressure to women who never gave birth. Women who delivered experienced a drop after their first birth of ? 3.32 mmHg (95% CI, ? 3.93, ? 2.71) and ? 1.98 mmHg (95% CI, ? 2.43, ? 1.53) in systolic and diastolic blood pressure, respectively. Subsequent pregnancies were associated with smaller reductions. These pregnancy-related reductions in blood pressure led to persistent differences in mean blood pressure, and at age 50, parous women still had lower systolic (? 1.93 mmHg; 95% CI, ? 3.33, ? 0.53) and diastolic (? 1.36 mmHg; 95% CI, ? 2.26, ? 0.46) blood pressure compared to nulliparous women. The findings suggest that the first pregnancy and, to a lesser extent, successive pregnancies are associated with lasting and clinically relevant reductions in systolic and diastolic blood pressure.     

Intrauterine growth retardation and blood pressure at age seven and eighteen.

The association between intrauterine growth retardation and blood pressure in middle childhood and early adulthood was examined. At age 7, after adjusting for sex and weight, the differences between normal children and those who had experienced intrauterine growth delay were 0.9 mmHg (95% CI -0.1 to 2.2) for systolic and 0 mmHg (-1.7 to 2.0) for diastolic blood pressure respectively. The differences between the blood pressures of intrauterine growth retarded infants with an appropriate ponderal index and those with a low ponderal index were 4.4 mmHg (-0.9 to 7.9) for systolic, and 3.8 mmHg (0.2 to 7.3) for diastolic blood pressure respectively. At age 18 the differences were much less pronounced. The association between blood pressure and the placental weight was also examined. The evidence from this sample lends weak support to the findings of other studies which suggest that there is an association between factors occurring before or around the time of birth and blood pressure in later life.     

Early and late growth and blood pressure in adolescence

OBJECTIVE: To assess the effect of growth during infancy and childhood on blood pressure in adolescence. DESIGN: Birth cohort study. SETTING: Pelotas, southern Brazil. PARTICIPANTS: 749 adolescents with complete information on birth weight and gestational age, as well as on anthropometric data at all three follow up visits (mean age 20 months, 42 months, and 15 years). MAIN OUTCOME MEASUREMENTS: Systolic and diastolic blood pressure at adolescence. RESULTS: After controlling for possible confounding variables, birth weight was negatively associated with systolic blood pressure, one unit increase in standard deviation score of birth weight for gestational age was associated with a decrease of 1.23 mm Hg (95% confidence intervals -2.03 to -0.43) in systolic blood pressure. Weight for age z score at the age of 15 years showed a strong positive association with systolic blood pressure, one unit increase in standard deviation score of birth weight for gestational age was associated with an increase of 4.4 mm Hg (95% confidence intervals 3.50 to 5.3). Diastolic blood pressure was not associated with birth weight. For adequate for gestational age infants, the positive association between weight in adolescence and blood pressure became stronger when previous weights were added to the model. CONCLUSION: This study showed that early--as well as--late catch up growth is associated with increased systolic blood pressure in adolescence, whereas only late catch up is related with diastolic blood pressure. These findings suggest that catch up growth, irrespective of age, is associated with increased blood pressure in adolescence.     

Prevalence of high blood pressure among schoolchildren in Cuiabá, Midwestern Brazil

OBJECTIVE: The ways in which basal blood pressure levels are obtained may lead to different prevalence estimates. The objective of the study was to estimate the prevalence of high blood pressure among schoolchildren and to compare systolic and diastolic means obtained from three measurements of arterial pressure. METHODS: This was a cross-sectional study among seven to ten-year-old schoolchildren (N=601) from public and private schools in the urban area of Cuiabá, midwestern Brazil, in 2005. Three different blood pressure measurements at ten-minute intervals were made during a single visit. Children were considered to have high blood pressure when their systolic and/or diastolic blood pressure reached levels greater than or equal to the 95th percentile in the reference table, in accordance with their gender, age and percentile height. To calculate the prevalence, the first and third blood pressure measurements were considered separately. RESULTS: There were statistically significant differences between the systolic and diastolic means from the three measurements of the study. The mean systolic and diastolic pressures from the third measurement of the study were 97.2 mmHg (SD=8.68) and 63.1 mmHg (SD=6.66) respectively. The prevalence of high blood pressure was 8.7% (95% CI: 6.4;10.9) from the first measurement and 2.3% (95% CI: 1.1;3.5) from the third measurement. There was no statistical difference in prevalence in relation to age, sex, skin color and type of school. CONCLUSIONS: In studies with a single visit, blood pressure measurements decrease significantly from the first to the third measurement. The third measurement seems to reveal blood pressure levels closer to the basal levels.     

Isolated systolic hypertension in Dutch middle aged and all-cause mortality: a 25-year prospective study

In the early 1950s, the blood pressure of 3901 Dutch civil servants and their spouses aged 40-65 years was measured in a general health survey. Isolated systolic hypertension (systolic pressure greater than 160 mmHg, diastolic pressure less than 90 mmHg) was observed in 6.3% of the women and 3.0% of the men. The prevalence increased with age and it was more common in women in all age groups. Using logistic regression, with adjustment for potential confounders (age, smoking, serum cholesterol, Quetelet index, alcohol consumption, haemoglobin level, pulse rate and diastolic blood pressure) the association of 15- and 25-year total mortality with isolated systolic hypertension was determined. Compared to normotensive people (systolic pressure less than or equal to 135 mmHg, diastolic pressure less than 90 mmHg), the risk of death from all causes was significantly higher for men with isolated systolic hypertension after 15 and 25 years of follow-up (odds ratio OR = 2.4, 95% confidence interval (CI) 1.2-4.8 and OR = 3.2, 95% CI 1.3-8.0). For women 15-years mortality risk was strongly associated with isolated systolic hypertension (OR = 3.7, 95% CI 1.4-9.7). The increased risk was less pronounced after 25 years of follow-up (OR = 1.7, 95% CI 0.96-3.0). Our results support those of other studies and indicate that isolated systolic hypertension is an important independent risk factor for all-cause mortality. Since isolated systolic hypertension may be an indicator for the early onset of ageing, it is important to study its determinants and to pay more attention to its diagnosis and treatment in middle-aged populations.     

Clinical validation of an automatic device measuring blood pressure in the fingers.

BACKGROUND: To assess the agreement between a new automatic device (FS-20D) using a cuff-oscillometric method to measure arterial blood pressure (BP) in the fingers and a standard mercury sphygmomanometer. METHODS: The blood pressure measurements were taken in a sequential order, in a sample of both normotensive subjects (n. 57) and slight to moderate hypertensive patients (n. 28) without vascular complications. RESULTS: The mean sphygmomanometer-monitor difference was 0.52 +/- 4.57 mmHg for systolic and 0.25 +/- 4.41 mmHg for diastolic values; the agreement limits were: SBP -8.6 divided by 9.6 mmHg, 95% CI: -0.5 divided by 1.5; DBP: -8.6 divided by 9.1 mmHg, 95% CI: -0.7 divided by 1.2. The grade of agreement between the monitor and the sphygmomanometer was "A" (British Hypertension Society) for both systolic and diastolic values (difference of readings < 5 mmHg: 82%; < 10 mmHg: 97% for systolic blood pressure, 98% of diastolic blood pressure). CONCLUSIONS: The monitor was proved to be reliable with a good level of precision and accuracy. The FS-20D monitor may be used in self-monitoring of blood pressure of patients with slight to moderate hypertension.     

Increases in hypertension and blood pressure during pregnancy with increased bone lead levels

Prior studies have revealed associations of current lead exposure (blood lead) and past lead exposure (bone lead) with risks of hypertension and elevated blood pressure. The authors examined the effects of blood and bone lead on hypertension and elevated blood pressure in the third trimester and postpartum among 1,006 women enrolled in Los Angeles prenatal care clinics between 1995 and 2001. The authors measured bone lead concentration by K-shell x-ray fluorescence in the tibia (mean = 8.0 micro g/g (standard deviation (SD) 11.4)) and calcaneus (heel) (mean = 10.7 micro g/g (SD 11.9)). Geometric mean prenatal and postnatal blood lead levels were 1.9 micro g/dl (geometric SD +3.6/-1.0) and 2.3 micro g/dl (geometric SD +4.3/-1.2), respectively. For each 10- micro g/g increase in calcaneus bone lead level, the odds ratio for third-trimester hypertension (systolic blood pressure > or =140 mmHg or diastolic blood pressure > or =90 mmHg) was 1.86 (95% confidence interval (CI): 1.04, 3.32). In normotensive subjects, each 10- micro g/g increase in calcaneus bone lead level was associated with a 0.70-mmHg (95% CI: 0.04, 1.36) increase in third-trimester systolic blood pressure and a 0.54-mmHg (95% CI: 0.01, 1.08) increase in diastolic blood pressure. Tibia bone lead concentration was not related to hypertension or elevated blood pressure either in the third trimester or postpartum, nor was calcaneus bone lead related to postpartum hypertension or elevated blood pressure. Past lead exposure influences hypertension and elevated blood pressure during pregnancy. Controlling blood pressure may require reduction of lead exposure long before pregnancy.     

大气细颗粒物对妊娠期血压的急性效应研究

目的 研究大气细颗粒物对妊娠期血压的影响,为进一步探讨妊娠高血压疾病的发病机制提供依据.方法 利用上海市孕产期保健队列研究数据及大气细颗粒物监测数据,采用广义相加混合效应模型等方法分析大气细颗粒物对妊娠期血压的急性和滞后效应.结果 研究于2010年共纳入7 402例孕晚期妇女,结果表明在仅考虑气温、湿度、季节和长期趋势及周末效应的情况下,PM1每增加一个四分位数间距(滞后0天、1天、3天和5天),妊娠期妇女收缩压可分别增加0.509mmHg (95％ CI:0.045 ～0.974)、0.504mmHg(95％ CI:0.047～0.961)、0.456mmHg (95％ CI:0.011 ～0.901)、0.466mmHg(95％ CI:0.028 ～0.904),差异均有统计学意义(均P＜0.05);调整气象条件、周末效应、季节因素、产妇年龄、孕产史、高血压家族史、孕前BMI的情况下,妊娠期妇女收缩压可分别增加0.503mmHg(95％CI:0.066 ～0.940)、0.486mmHg(95％CI:0.055 ～0.916)、0.443mmHg(95％ CI:0.022 ～0.865)、0.480mmHg (95％ CI:0.064 ～0.895),差异均有统计学意义(均P＜0.05),但PM2.5浓度对妊娠期收缩压的影响差异无统计学意义(均P＞ 0.05).在仅考虑气温、湿度、季节、长期趋势及周末效应的情况下,PMI每增加一个四分位数间距,滞后3天妊娠期妇女舒张压可增加0.402mmHg(95％CI:0.027 ～0.777),差异有统计学意义(P＜0.05),然而在调整上述因素后,PM2.5水平变化对妊娠期舒张压的影响无统计学意义(P＞0.05).结论 PM1是妊娠期血压增高的独立危险因素,是较有价值的附加空气质量指标,孕期妇女应根据雾霾预警进行及时有效的防护.     

Exposure to a nutrition supplementation intervention in early childhood and risk factors for cardiovascular disease in adulthood: evidence from Guatemala

To study the role of nutrition in the association of birth size and childhood growth with development of cardiovascular disease, the authors in 2002-2004 surveyed 665 men and 790 women aged 25-42 years who had been exposed as children to a community-randomized nutrition supplementation intervention in four villages in eastern Guatemala. Exposure was associated with a lower fasting glucose level (7.0 mg/dl, 95% confidence interval (CI): 0.5, 13.5) for exposure at ages 36-72 months; lower systolic blood pressure (3.0 mmHg, 95% CI: 0.4, 5.6) for exposure at ages 24-60 months; and a lower triglyceride level (sex-adjusted; 22.2 mg/dl, 95% CI: 0.4, 44.1) and higher high density lipoprotein cholesterol level (males only; 4.7 mg/dl, 95% CI: 1.5, 7.9) for exposure prior to age 36 months. Improved nutrition at any age prior to 7 years was not associated with diastolic blood pressure, total or low density lipoprotein cholesterol level, or prevalence of the metabolic syndrome. Interventions designed to address nutrient deficiencies and ameliorate stunting that are targeted at pregnant women and young children are unlikely to increase cardiovascular disease risk later in life and may instead lower the risk.     

The association of birth weight with developmental trends in blood pressure from childhood through mid-adulthood: the Bogalusa Heart study

Low birth weight has been found to be associated with cardiovascular mortality and morbidity and with an adverse profile of several cardiovascular risk factors. The inverse association between birth weight and blood pressure was consistently reported from many populations. Using longitudinal data from the Bogalusa Heart Study (Louisiana), the authors investigated the association between birth weight and progression of blood pressure through early adulthood, comparing that relation between African Americans and Whites. Birth data of 2,275 participants, screened two or more times in the Bogalusa Heart Study between 1973 and 2001, were retrospectively obtained from birth certificates and were linked to their clinical, laboratory, and socioeconomic and lifestyle data in the Bogalusa Heart Study data sets. Birth weight was inversely associated with systolic blood pressure, diastolic blood pressure, and pulse pressure (p相似文献   

Nine-year changes in cardiovascular disease risk factors with weight maintenance in the atherosclerosis risk in communities cohort

Few studies have focused on the impact of weight maintenance on cardiovascular disease risk factors or addressed whether changes differ by baseline weight status and medication usage. The authors examined these issues using 9 years of follow-up data on 3,235 men and women from the Atherosclerosis Risk in Communities (ARIC) Study who were aged 45-64 years at baseline (1987-1989). In participants not using medications, glucose (3.0 mg/dl, 95% confidence interval (CI): 2.4, 3.5) and triglycerides (10.1 mg/dl, 95% CI: 8.3, 11.9) increased, while total cholesterol (-9.6 mg/dl, 95% CI: -10.6, -8.6), low density lipoprotein cholesterol (-9.9 mg/dl, 95% CI: -10.9, -9.0), and high density lipoprotein cholesterol (-1.7 mg/dl, 95% CI: -2.1, -1.3) decreased. Systolic blood pressure (7.9 mmHg, 95% CI: 7.3, 8.4) increased, but diastolic blood pressure (-1.1 mmHg, 95% CI: -1.4, -0.7) declined. Normal weight (body mass index: 18.5-<25.0 kg/m(2)) participants had smaller increases in glucose compared with obese (body mass index: >/=30.0 kg/m(2)) participants. In contrast, the authors found less favorable changes in total, low density lipoprotein, and high density lipoprotein cholesterol, triglycerides, and diastolic blood pressure among normal weight compared with obese participants who maintained their weight. These patterns were similar across weight status groups regardless of medication usage.     

活产双胎低出生体重儿影响因素分析

目的探讨活产双胎低出生体重与相关因素关系。方法将657对活产双胎按出生体重分为体重均低组、单低体重组和体重正常组,配对分析双胎性别、出生次序与低出生体重的关系;分析母亲因素（孕龄、孕周、孕次、产次、血压、血红蛋白等）与出生体重的关系。结果双胎中第2个出生胎儿为低体重者明显多于第1个出生胎儿,女婴显著多于男婴。各体重组母亲孕周、产次比较差异有统计学意义;低体重组母亲孕初舒张压显著低于正常组,血红蛋白值始终高于体重正常组。结论双胎低出生体重与胎儿性别、出生顺序、母亲孕周、产次有关。双胎母亲孕期血压、血红蛋白与胎儿低出生体重间的关系是否属于对双胎妊娠的一种适应,有待进一步探讨。