Effect of high-dose cholecalciferol (vitamin D3) on bone and body composition in children and young adults with HIV infection: a randomized, double-blind, placebo-controlled trial.

It is unknown whether vitamin D supplementation positively impacts body composition and bone outcomes in children and young adults with HIV. This RCT found that despite increasing 25(OH)D concentrations, high dose vitamin D3 supplementation did not impact bone or body composition in children and young adults with HIV infection. INTRODUCTION: The objective of this paper was to determine the impact of high-dose daily cholecalciferol (vitamin D3) supplementation on body composition and bone density, structure, and strength in children and young adults with perinatally acquired (PHIV) or behaviorally acquired (BHIV) HIV infection. METHODS: Participants were randomized to receive vitamin D3 supplementation (7000 IU/day) or placebo for 12 months. Serum 25-hydroxyvitamin D [25(OH)D] concentrations, dual energy X-ray absorptiometry (DXA) of the whole body and lumbar spine, and peripheral quantitative computed tomography (pQCT) of tibia sites were acquired at 0, 6, and 12 months. DXA and pQCT outcomes were expressed as sex- and population-ancestry specific Z-scores relative to age and adjusted for height or tibia length, as appropriate. RESULTS: Fifty-eight participants (5.0 to 24.9 years) received vitamin D3 supplements (n = 30) or placebo (n = 28). At enrollment, groups were similar in age, sex, population ancestry, growth status, serum 25(OH)D concentrations, body composition, and size-adjusted bone measures. Median 25(OH)D concentrations were similar (17.3 ng/mL in the vitamin D3 supplementation group vs 15.6 ng/mL in the placebo group), and both groups had mild bone deficits. At 12 months, 25(OH)D rose significantly in the vitamin D supplementation group but not in the placebo group (26.4 vs 14.8 ng/mL, respectively, p < 0.008). After adjusting for population ancestry, sex, antiretroviral therapy use, and season, there were no significant treatment group differences in bone or body composition outcomes. CONCLUSIONS: Despite increasing 25(OH)D concentrations, 12 months of high-dose vitamin D3 supplementation did not impact bone or body composition in children and young adults with HIV infection.

Total Energy Expenditure of Infants with Congenital Heart Disease Who Have Undergone Surgical Intervention.

Growth failure is often observed in infants with congenital heart disease (CHD); it is unclear, however, whether growth failure is due to increased total energy expenditure (TEE). An observational study of infants with CHD and surgical intervention within the first 30 days of life and healthy infants of similar age was undertaken. TEE was measured using the doubly labeled water method in 3-month-old infants (n = 15 CHD, 12 healthy) and 12-month-old infants (n = 11 CHD, 12 healthy). Multiple linear regression models were fit to examine the association between health status (CHD vs. healthy) and TEE. The accuracy of equations for calculating TEE was also determined. TEE for CHD infants was not significantly different from healthy infants at 3 and 12 months; TEE in CHD infants was 36.4 kcal/day higher (95 % CI -46.3, 119.2; p = 0.37) and 31.7 kcal/day higher, (95 % CI -71.5, 134.8; p = 0.53) at 3 and 12 months, respectively, compared to healthy infants. The 2002 Dietary Reference Intake (DRI) equation and the 1989 Recommended Dietary Allowance equation over-estimated measured TEE to a lesser extent than CHD specific equations; the 2002 DRI yielded the smallest mean difference between calculated versus measured TEE (difference 79 kcal/day). During the first year of life, TEE of infants with CHD and interventional surgery within the first month of life was not different than age-matched healthy infants. When calculating TEE of ≤12-month-old infants with CHD who have undergone surgical intervention, the 2002 DRI equation may be used as a starting point for estimating initial clinical energy intake goals.

The impact of vitamin D3 supplementation on muscle function among HIV-infected children and young adults: a randomized controlled trial.

OBJECTIVES: We tested the hypothesis that daily vitD3 supplementation increases neuromuscular motor skills, jump power, jump energy, muscular force, and muscular strength. METHODS: This was a secondary analysis of a randomized controlled trial of 12-months of oral 7,000 IU/day vitD3 supplementation or placebo among 56 persons living with HIV aged 9-25 years. Neuromuscular motor skills were quantified using the Bruininks-Oseretsky Test of Motor Proficiency. Power was quantified using peak jump power, and energy was quantified using peak jump height. Muscular force was quantified using isometric ankle plantar- and dorsiflexion, isokinetic knee flexion and extension. Muscular strength was quantified using isometric handgrip strength. RESULTS: After 12-months, serum 25-hydroxyvitamin D [25(OH)D] was higher with supplementation versus placebo (ß=12.1 ng/mL; P<0.001). In intention-to-treat analyses, supplementation improved neuromuscular motor skills versus placebo (ß=1.14; P=0.041). We observed no effect of supplementation on jump power, jump energy, muscular force, or muscular strength outcomes versus placebo. CONCLUSIONS: Among HIV-infected children and young adults supplementation with daily high-dose vitD3 increased concentration of serum 25(OH)D and improved neuromuscular motor skills versus placebo.

Predictive power of first morning glucose and the ketogenic diet.

The purpose of this study was to determine if hypoglycemia or hyperglycemia predicts the response to a ketogenic diet (KD) in a cohort of children with intractable epilepsy. We evaluated whether morning blood glucose during the initial 21 days after initiation of the KD in children with IE was related to seizure reduction after 3 months of treatment. The relation between change in weight status and blood glucose was also explored. Fasting morning whole blood glucose was measured each day for the first 21 days after initiation of KD. Weight and height were obtained at baseline, day of discharge, and at 0.5 and 1 month of full KD therapy. Associations among clinical response to the KD (responder status defined as >50% reduction of seizure frequency at 3 months), hypoglycemia, hyperglycemia, style of KD initiation protocol (fasting or gradual) and weight status were evaluated. Forty-five subjects age 1-12 years were enrolled. KD responder status was not associated with low or elevated blood glucose or type of initiation style protocol. Variability in day-to-day blood glucose also did not predict response to KD. Children who had declining weight status during KD initiation were more likely to be hypoglycemic during full KD therapy. Low blood glucose during KD therapy was not necessary for clinically significant seizure reduction. Hypoglycemia was related to declining weight status irrespective of initiation style protocol. An effective KD can be provided in a manner to minimize side-effects and maximize efficacy.

Young maternal age and preterm labor.

PURPOSE: The relationship among young age, biologic immaturity (as indexed by low gynecologic age), and the causes of preterm delivery (idiopathic preterm labor [PTL], premature rupture of the membranes [PROM], and medical indications) were investigated among 605 primigravidas from the Camden Study. METHODS: The sample consisted of 366 young adolescents < 16 years at the time of their last menstrual period (LMP) and 239 older women, 18-29 years at LMP (controls). The young adolescents were significantly shorter, thinner, had younger ages at menarche, and over a third (36.3%) were of low gynecologic age, i.e., their chronologic age was 2 or fewer years more than their age at menarche. RESULTS: Adjusting for ethnicity, cigarettes smoked/day, weight gain rate, height, fetal sex, gestational diabetes mellitus, and pregnancy-induced hypertension, young adolescents overall had a nearly 75% increased risk of PTL (adjusted odds ratio [AOR] = 1.74, 95% confidence interval [95% CI]: 1.07-2.84), and preterm delivery with PTL (AOR = 2.08, 95% CI: 1.08-4.00). There was a modest decreased risk of preterm delivery among young gravidas attributable to other causes, such as PROM or medical indications (AOR = 0.70, 95% CI: 0.28-1.75). This increased risk of PTL and preterm delivery with PTL was principally attributable to biologic immaturity. Young age with low gynecologic age was associated with a twofold risk of PTL (AOR = 2.15, 95% CI: 1.19-3.89) and preterm delivery with PTL (AOR = 2.64, 95% CI: 1.23-5.65), while the risk associated with young age and higher gynecologic age was only increased moderately. CONCLUSIONS: Young adolescents, and especially those of low gynecologic age, appear prone to PTL and are at increased risk for preterm delivery through this pathway.

PIP: The relationship between young maternal age and preterm delivery was investigated in a subsample of 605 primigravidas enrolled in the Camden (New Jersey, US) Study. Included were 366 adolescents under 16 years of age (cases) and 239 women 18-29 years of age (controls). 36.3% of young mothers had a low gynecological age (i.e., their chronological age was 2 or fewer years more than their age at menarche). After adjustment for ethnicity, cigarette smoking, weight gain rate, height, fetal sex, gestational diabetes mellitus, and pregnancy-induced hypertension, the odds ratio (OR) of preterm labor among young adolescents was 1.74 (95% confidence interval (CI), 1.07-2.84) and that of preterm delivery was 2.08 (95% CI, 1.08-4.00). There was a modest decreased risk of preterm delivery attributable to other causes (e.g., premature rupture of the membranes) among the youngest women (OR, 0.70; 95% CI, 0.28-1.75). Young age with low gynecological age was associated with a 2.15 OR (95% CI, 1.19-3.89) of preterm labor and a 2.64 OR (95% CI, 1.23-5.65) of preterm delivery with preterm labor. The risk associated with young age and higher gynecological age was increased only moderately. These findings suggest that it is the biological immaturity often associated with young age, rather than young maternal age per se, that increases the risks of adolescent pregnancy. The association between low gynecological age and preterm labor is presumed to reflect an irritability of the adolescent uterus, a sensitivity to dehydration, and/or an altered hormonal milieu that promotes maternal development at the expense of fetal well-being.

Use of multivitamin/mineral prenatal supplements: influence on the outcome of pregnancy.

The objective of this study was to examine the association of prenatal multivitamin/mineral supplement use during the first and second trimesters of pregnancy by low income, urban women in the Camden Study (1985-1995, n = 1,430) and preterm delivery (< 37 completed weeks) and infant low birth weight (< 2,500 g). Prenatal supplement use was corroborated by assay of circulating micronutrients at entry to care (no differences) and week 28 gestation (increased concentrations of folate and ferritin for supplement users). Compared with women who entered care during the first or second trimester but did not use prenatal supplements, supplement use starting in the first or second trimester was associated with approximately a twofold reduction in risk of preterm delivery. After controlling for potential confounding variables, risk of very preterm delivery (< 33 weeks' gestation) was reduced more than fourfold for first trimester users and approximately twofold when use dated from the second trimester. Infant low birth weight and very low birth weight (< 1,500 g) risks were also reduced. Risk of low birth weight was reduced approximately twofold with supplement use during the first and second trimester. Diminution in risk was greater for very low birth weight infants, amounting to a sevenfold reduction in risk of very low birth weight with first trimester supplementation and a greater than sixfold reduction when supplement use started in the second trimester. Thus, in low income, urban women, use of prenatal multivitamin/mineral supplements may have the potential to diminish infant morbidity and mortality.

Implications of the Camden Study of adolescent pregnancy: interactions among maternal growth, nutritional status, and body composition.

One of the principal goals of the Camden Study over the past decade has been to document the extent to which pregnancy during adolescence is affected by continued maternal growth. Findings from the Camden Study relating to the other main goal, the effects of maternal growth during pregnancy on the outcome of pregnancy (maternal-fetal competition), are reviewed elsewhere. Contrary to widely held beliefs, we have found that there is considerable growth in late adolescence for girls, and, in particular, continued development of weight (> 1 kg/year) and increases in subcutaneous fatness at central sites. Thus, when pregnancy occurs during this final phase of adolescent growth, the normal growth processes may be exacerbated. That is, the adolescent potential for weight gain (as fat) may be exploited. Along with others, we have documented that adolescent pregnancy is associated with larger gestational weight gains. Using methods sufficiently sensitive to detect maternal growth prospectively, we also found that the larger-than-average total weight gains among adolescents appear attributable primarily to the growing adolescent gravidas and reflect their continued accrual of subcutaneous fat and increased risk for weight retention. Excessive gestational weight gain, as is more common among growing adolescent gravidas, appears to exacerbate the accumulation of fat at central sites. Aside from the consequences to the outcome of pregnancy, adolescents who begin their childbearing early while still growing themselves, such as those we have followed in the Camden Study over the past decade, may be at particularly increased risk for overweight and obesity. Further, the excessive deposition of subcutaneous fat at central body sites, as we have documented for adolescent pregnancy, will often in later life presage the development of cardiovascular disease, noninsulin-dependent diabetes mellitus (NIDDM), and hypertension. Thus, far from being benign, pregnancy during adolescence, particularly when the adolescent is herself still growing, may contribute to long-term risk for obesity-related diseases and diminish the quality of life.

Dietary and serum folate: their influence on the outcome of pregnancy.

We examined the influence of folate intake from diet and supplements b y 28 wk of gestation and third trimester circulating concentrations of serum folate on the outcome of pregnancy in women from Camden, NJ. Mean daily folate intake by week 28 included both dietary and supplemental folate obtained prospectively in 832 women. Circulating concentrations of serum folate as well as serum vitamin B-12 were assayed at 28 wk of gestation (+/- 2 wk) by radioimmunoassay. The outcomes of interest included preterm delivery (<37 wk) and infants with low birth weight (<2500 g). Mean folate intake was significantly correlated with circulating concentrations of serum folate (r=0.17, P<0.001). Women with a low mean daily folate intake (

Gestational weight gain, pregnancy outcome, and postpartum weight retention.

OBJECTIVE: To determine whether the risk of maternal overweight associated with an excessive rate of gestational gain needs to be balanced against the risks of impaired fetal growth associated with a low rate of gain. METHODS: Rate of gestational weight gain was measured prospectively in a sample of 274 young, low-income, and primarily minority women (12-29 years old) with pregravid body mass indices (BMI) in the normal range (19.8-26.0). We defined an excessive rate of gain between 20-36 weeks' gestation as one greater than 0.68 kg/week, and a low rate of gain as one less than 0.34 kg/week. Women were followed-up at 4-6 weeks and 6 months postpartum. RESULTS: Rate of measured gestational gain between 20-36 weeks' gestation was associated with total weight gain based on pregravid weight, with infant birth weight and gestation duration, and with maternal overweight (BMI greater than 26) and weight retention postpartum. Infant birth weight and gestation duration were significantly reduced for women with low rates of gain, and there was no significant difference between women with excessive and moderate gains. Despite little difference in pregravid BMI, women with excessive rates of gain retained more weight overall, attained a greater postpartum BMI, and had higher levels of subcutaneous fat and overweight. Maternal anthropometric status showed little change between 4-6 weeks and 6 months postpartum. CONCLUSION: Weight gained at an excessive rate by women with a pregravid BMI in the normal range does not greatly enhance fetal growth and gestation duration, contributing instead to postpartum maternal overweight.

One-year changes in weight and fatness in girls during late adolescence.

OBJECTIVE: To document postmenarcheal growth and changes in weight and fatness in girls. DESIGN: Mixed longitudinal study to determine yearly growth increments. PARTICIPANTS: Six hundred sixty-eight postmenarcheal girls, initially ages 13 to 17 years, from two Philadelphia high schools. Overall, 61.4% of the girls were white, 15.7% black, 16.8% Puerto Rican Hispanic, and 6.1% of other ethnicities (non-Puerto Rican Hispanic or Asian). OUTCOME MEASURES: Height (in centimeters), weight (in kilograms), and triceps and subscapular skinfold thicknesses (in millimeters) were measured initially and after 1 year. The anthropometric measures were analyzed both cross-sectionally by age cohort and longitudinally. RESULTS: Viewed cross-sectionally by chronologic age groups and adjusted for ethnicity, gynecologic age, cigarette smoking, and late maturation (menarche > or = 14 years), there were no statistically significant trends with age in height, weight, body mass index (kilograms per m2), triceps, or subscapular skinfold thicknesses. Nevertheless, there were significant trends in velocity with increasing chronologic age. On the average, postmenarcheal girls gained about 6.5 kg (14.3 lb) during late adolescence from about 1.5 years after menarche to age 18 years. Height and triceps skinfolds showed significantly decreasing velocities, whereas there was a significant monotonic increase in velocity with age for skinfolds at the subscapular site. CONCLUSIONS: Even with normal weight gain during late adolescence in girls, there seems to be greater potential for fat deposition centrally. Thus, excessive weight gain during late adolescence may exacerbate the normal processes of fat deposition, leading to large gains in central fat, and thereby increasing the long-term risk for metabolic and cardiovascular diseases later in life.

Fetal growth and the etiology of preterm delivery.

OBJECTIVE: To confirm that preterm delivery is associated with fetal growth restriction (FGR), and to determine if the various etiologies of preterm delivery are associated with the same degree and type of FGR. METHODS: Two hundred ninety young, primarily minority gravidas who had routine initial ultrasound examinations also had subsequent ultrasound examinations at 32 weeks' gestation. Fetal growth characteristics were compared between preterm (less than 37 weeks' gestation) and term deliveries, and among preterm deliveries with medical or obstetric indications, premature rupture of membranes (PROM), and spontaneous preterm labor. RESULTS: Forty-six infants (15.9%) were born preterm. At 32 weeks' gestation, all fetuses later delivered preterm were already smaller than fetuses later delivered at term (P < .05) for all dimensions: head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and femur length (FL). However, after stratifying by cause of preterm delivery for those fetuses later delivered for medical or obstetric indications, we found that only AC was decreased (P < .01) and that the HC-AC ratio was elevated (asymmetric FGR). Neonates delivered after unsuccessfully treated PROM or preterm labor were symmetrically smaller in all characteristics (HC, AC, BPD, and FL). CONCLUSION: By 32 weeks' gestation, fetuses later delivered preterm are already significantly smaller than fetuses later delivered at term. However, when stratified by the etiology of preterm delivery, infants delivered preterm for medical or obstetric indications had asymmetric growth patterns, which suggests a growth failure late in pregnancy. Infants delivered preterm after PROM or after failed or no tocolysis for spontaneous preterm labor were proportionately smaller, implying an overall slowing of growth that may originate early in pregnancy and possibly demonstrate a more chronic stress.

Maternal growth during pregnancy and the competition for nutrients.

The influence of maternal growth in knee height during pregnancy on birth weight, gestation, and maternal body composition was examined in 318 teenagers (144 growing, 174 nongrowing) and 276 mature women from the Camden Study. Body-composition differences associated with maternal growth did not arise until after 28 wk gestation, when growing gravidas continued to accrue fat, had larger gestational gains, and retained more of their gestational weight gain postpartum. Nevertheless, still-growing young mothers had infants with lower birth weight, particularly when the mother continued to accrue higher amounts of fat on the arm or back (subscapular site) late in gestation. Thus, despite an apparently sufficient weight gain and the accumulation of abundant stores during pregnancy, young still-growing women appeared not to mobilize fat reserves late in pregnancy to enhance fetal growth, apparently reserving them instead for their own continued development.

PIP: The influence of maternal growth in knee height during pregnancy on birth weight, gestation, and maternal body composition was examined in 318 teenagers (144 growing, 174 nongrowing) and 276 mature women from the prospective study of nutrition and pregnancy in Camden, NJ, one of the poorest cities in the continental United States. Enrollments included parous and nulliparous teenagers younger than 19 years of age along with more mature parous and nulliparous control subjects (aged 19-29 years) delivering between July 1987 and January 1992. Measures of maternal body composition taken at entry to prenatal care and at 28 weeks of gestation indicated little difference according to maternal growth in knee height. By the beginning of the third trimester, all groups had similar amounts of subcutaneous body fat and muscle. After 28 weeks, growing gravidas failed to lose fat at the sub-scapular site and tended to accrue fat at the triceps site, whereas mature women and nongrowing teenagers lost fat from their upper arms and backs. The more extreme example of this change in body composition for arm-fat area ( 2.6 square cm in 42% of growers vs. 18% of nongrowing teenagers and 21% of mature women, p 0.001) or subscapular skinfold thickness ( 1.5 mm in 32% of growers vs. 25% of nongrowing teenagers and 22% of mature women, p= 0.07) also was more prevalent among growers. When energy intake was adequate but growth continued, infant birth weight was reduced (-86 g), but when intake was inadequate and the mother continued to grow, the birth weight deficit was quite large (-320 g). Ratios of maternal net weight gain and infant birth weight to total gestational gain suggested that, when the mother was still growing, she retained a larger proportion of the total gestational gain. In the growing gravidas, infant weight was a significantly smaller proportion of total gestational gain; conversely, net maternal gain (at delivery) was a significantly larger proportion.

Changes in maternal upper arm fat stores are predictors of variation in infant birth weight.

The relationship between changes in maternal subcutaneous fat and infant birth weight was studied in 608 low income women. A loss of upper arm fat area (> 6.4 cm2), measured from 28 wk gestation to 4-6 wk postpartum, was associated with greater birth weight (+144 g, P < 0.01). However, when pregravid weight was low (< 25th percentile for age), a loss of upper arm fat area was associated with a birth weight lower by more than 300 g than that for women with higher pregravid weights who also lost fat, indicating that maternal stores among those with low weight may have been relatively depleted. Continued gains in upper arm fat area (> 5 cm2) from 28 wk gestation to the postpartum period was also associated with a lower birth weight (-123 g, P < 0.02). The mothers who gained upper arm fat late in pregnancy or continued to accrue fat in the postpartum period had the largest gestational weight gains, bore infants who were smaller, and retained the most weight postpartum. Thus, change in upper arm fat is a significant predictor of variation in infant birth weight.

Low zinc intake during pregnancy: its association with preterm and very preterm delivery.

Zinc affects growth, development, and reproduction. However, the effect of poor maternal zinc nutriture, usually measured as plasma zinc, on poor pregnancy outcome has not been consistent. The influence of dietary zinc on pregnancy outcome was examined in a cohort of 818 pregnant girls and women from a poor urban community in Camden, New Jersey (1985-1990). Zinc intake in this sample was 11.1 mg/day, a level ascertained from averaged 24-hour dietary recalls during pregnancy. Gravidas with low zinc intake (< or = 6 mg/day, amounting to 40% of the recommended dietary allowance for pregnancy) had lower caloric intake and multivitamin usage as well as a higher incidence of inadequate weight gain during pregnancy and iron deficiency anemia at entry to prenatal care compared with those with higher intakes. A low zinc intake was associated with approximately a twofold increase in the risk of low birth weight (< 2,500 g) after controlling for calories and other confounding variables. The risk of preterm delivery (< 37 completed weeks) was also increased, particularly when rupture of the membranes preceded the onset of labor (adjusted odds ratio = 3.46, 95% confidence interval 1.04-11.47). A low intake of dietary zinc earlier in pregnancy was associated with a greater than threefold increase in the risk of very preterm delivery (< 33 completed weeks). In conjunction with iron deficiency anemia at entry to prenatal care, the adjusted odds ratio for very preterm delivery with low zinc intake was 5.44 (95% confidence interval 1.58-18.79). Among the urban poor, a marginal zinc intake during pregnancy may play an important role in the duration of gestation and is associated with increased risk of preterm and very preterm delivery.

Maternal growth during pregnancy and lactation.

Until recently, it was widely accepted that the small amount of statural growth observed in young gravidas was unlikely to be clinically significant, to alter maternal nutritional status, or to threaten fetal growth. We show that this belief reflects incomplete information about growth and the use of inappropriate measuring techniques by investigators. We have done this using illustrations drawn primarily from the Camden Study, a controlled, prospective study of nutrition and growth during adolescent pregnancy. Maternal growth during pregnancy is prevalent and associated with increased gestational weight gain. In the postpartum period it is associated with increased triceps skinfolds, arm fat area and weight retention, all of which occur at caloric intakes comparable with those of pregnant, non-growing adolescents and mature women. Unlike pregnancy where research is continuing, the sequelae of maternal growth during lactation are virtually unstudied.

PIP: Inaccurate inferences about maternal growth based on measurements in medical records and the inability of traditional measuring techniques (e.g. serial measurements of stature) to detect maternal growth led many clinicians to erroneously believe that the limited statural growth in young pregnant women probably does not change maternal nutritional status or jeopardize fetal growth. In Camden, New Jersey, clinicians used the knee high measuring device during pregnancy and the postpartum period to measure the lower leg of pregnant adolescents and mature controls so they could monitor maternal growth during pregnancy. They measured the lower leg because it is less susceptible to the effects of gestational weight gain and forward curvature of the spine during pregnancy. Pregnant adolescents exhibited considerable positive increments in knee height growth while mature controls exhibited small decrements. So pregnant teens are growing in knee height but shrinking in stature as a result of weight gain and lordosis, suggesting that limited or no maternal growth occurs. Caloric intakes of the growing and nongrowing adolescents and the mature controls are essentially the same. Six weeks after delivery, adolescents who grow in knee height during pregnancy retain significantly more weight (3 kg more) than those who do not grow in knee height (p 0.01), indicating that greater weight retention is linked to maternal growth. The triceps of postpartum adolescents arm much larger and the arm fat area much greater in those who grow during pregnancy (p 0.05). Maternal growth in knee height during pregnancy is related to reduced infant birth weight, indicating that fat reserves in growing pregnant teens do not support fetal growth but support the mother's continued development. Few studies have examined growth and health status of breast feeding adolescents. This is an area that needs to be studied.

Pulse rate, blood pressure and body composition in black adolescents: the Philadelphia Blood Pressure Project.

Patterns of pulse rate, blood pressure (BP), and body size and composition are investigated in a black urban sample of over 600 adolescents (aged 12-17) in Philadelphia as part of the Philadelphia Blood Pressure Project. Supine and seated pulse rates decline after the age of 13 in both males and females, and females have significantly higher pulse rates than males, ranging from 1.6 to 4.7 beats/30 sec higher depending upon chronological age and position. Seated pulse rates are consistently higher than supine in both sexes ranging from 1.3 to 2.9 beats/30 sec depending upon chronological age. Pulse rate and both systolic blood pressure (SBP) and diastolic phase IV blood pressure (DBP) show a positive association throughout adolescence for females (r = 0.16 SBP, r = 0.24 DBP) but not for males (r = -0.06 SBP, r = 0.06 DBP). Females in the highest diastolic IV blood pressure stratum (greater than 85%) maintain higher pulse rates throughout adolescence, while males with the highest DBP have higher pulse rates in early adolescence (ages 12-14) but lower pulse rates in later adolescence (ages 16 and 17). Females with the highest DBP also show consistently higher measures of relative fatness (triceps skinfolds) throughout adolescence. Males with the highest DBP have greater triceps skinfolds in early adolescence and lower triceps in later adolescence, a pattern similar to that shown for pulse rate. For DBP, triceps is significantly and positively associated with pulse rate in the upper DBP percentile group (p less than 0.05). Thus, females with the highest blood pressure during adolescence are characterized by higher pulse rate and greater fatness. Males show this same pattern in early adolescence; whereas, in contrast, the older adolescent males in our sample with the highest DBP are characterized by lower pulse rates, relatively decreased fatness, and increased muscularity. Our findings suggest that, at least in some older black male adolescents, a higher DBP may reflect a decrease in cardiac output as indicated by a lower pulse rate, or an increase in peripheral vascular resistance, possibly associated with relatively decreased fatness and increased muscle mass for size.