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PubMed1997

Significance of low birthweight for gestational age among very preterm infants.

OBJECTIVE: To estimate the risk of specific adverse neonatal events resulting from the combined effects of prematurity and low birthweight in very preterm infants (delivered at 24-31 weeks of gestation). DESIGN: A cohort study of specific adverse neonatal events in preterm infants born at between 24 and 31 weeks of gestation. SETTING: Pavia, Italy. POPULATION: Two hundred and thirty singleton infants with sonographically confirmed gestational age, delivered at 24 to 31 weeks of gestation. METHODS: To evaluate the impact of a lower than expected birthweight on selected neonatal events independently of gestational age, we calculated birthweight standard deviation scores (differences between actual birthweight and fitted birthweight divided by fitted standard deviation) for each week of gestation. RESULTS: After adjustment for gestational age and other confounders, there was a significant linear trend relating a decreasing birthweight SDS to an increased likelihood of neonatal death, intraventricular haemorrhage, severe respiratory distress syndrome, and acidosis. Compared with infants with SDS > or = 0 (> or = 50th centile of birthweight), infants with birthweight SDS < -1 (< 16th centile) had increased odds for neonatal death [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.42-9.6], grade III-IV intraventricular haemorrhage (OR 17.5, 95% CI 4.04-75.9), and neonatal acidosis (OR 3.22, 95% CI 1.41-7.4). The significance of birthweight SDS as a predictor of neonatal outcome, however, was lower than that of gestational age. CONCLUSIONS: A lower than expected birthweight affects the likelihood of several adverse neonatal events in very preterm infants. However, a decreasing birthweight SDS affects neonatal outcome less than decreasing gestation does.

Adult↗
PubMed2000

Birthweight percentiles by gestational age in multiple births. A population-based study of Norwegian twins and triplets.

OBJECTIVE: To assess secular trends for birthweight by gestational age in twins in Norway and to develop current national birthweight standards by gestational age for twin and triplet births using population-based data. MATERIAL AND METHODS: The analysis of secular trends for birthweight and gestational age in twins was based on 32,379 twin livebirths (1967-95). Taking into account the observed secular trends in birthweight for 35-40 weeks of gestation, data on twins born during 1987-95 only were included in the calculation of birthweight percentiles for 35-40 weeks, while for lower and upper weeks, data on twins born during 1967-95 were used. The construction of birthweight-for-gestation curves for triplets was based on the data on 690 triplets. RESULTS: Whereas the overall mean birthweight and gestational age decreased in 1987-95 compared with the previous years, the mean birthweights by gestational age for the 35-40 weeks of gestation was significantly higher in 1987-95. Male twins weighed more than female twins throughout the gestation with consistent and significant differences from 27 to 42 weeks of gestation. Smoothed curves for birthweight-by-gestational-age percentiles of male and female twins are plotted. The birthweight-by-gestational-age curves of triplets were almost identical with twin curves before 30 weeks of gestation, starting to diverge from them progressively thereafter. The intrauterine growth of twin births also starts to differ markedly from singletons at approximately 30 weeks of gestation. CONCLUSION: This study shows that plurality-specific birthweight-by-gestation standards should be used for assessment of fetal growth in multiple births rather than singleton standards.

Birth Weight↗
PubMedDate not supplied

Current and future impact of rising multiple birth ratios on low birthweight.

Before 1980, multiple births with their increased risk of low birthweight comprised too small a proportion of births in the United States to have a significant impact on overall low birthweight levels; the recent steep rise in the multiple birth ratio has heightened their influence, however. Between 1980 and 1992 the white multiple birth ratio rose from 18.5 to 24.0 multiple births per 1,000 births. While the overall level of white low birthweight newborns increased slightly between 1980 and 1992 (from 5.7 percent to 5.8 percent), low birthweight for white singletons actually improved, declining from 4.9 to 4.7 percent. Thus, the increase in overall white low birthweight levels is a reflection of the increase in white multiple births and, to a much lesser extent, of the small increase in low birthweight among these births. Black multiple birth ratios and overall low birthweight also rose in this period. The black multiple birth ratio increased from 24.4 in 1980 to 28.2 per 1,000 births in 1992, and low birthweight rose from 12.7 to 13.3 percent. Although low birthweight for black singletons also increased (from 11.5 percent to 11.8 percent), the increase was at a slower pace than for all pluralities combined. Thus, for both white and black births, overall trends in low birthweight mask the disparate patterns of singleton and multiple births. It is, therefore, essential to examine low birthweight trends by plurality to assess accurately changes in this key indicator of infant health.

Adult↗
PubMedDate not supplied

Assessing the net effect of young maternal age on birthweight.

Pregnancy during adolescence presents an increased risk for low birthweight, which is attributed not only to physiologic immaturity but also to socioeconomic and behavioral risk factors associated with adolescence. The independent effect of maternal age on birthweight is difficult to ascertain because age is closely entangled with these risks. We first examined the effect of being an adolescent mother on these risk pathways and then estimated the net effect of maternal age on birthweight (weight in grams or low birthweight (<2500 g)) after controlling for these risks. We used data on 214 adolescent and 415 adult primiparae and their infants from the Cebu Longitudinal Health and Nutrition Survey, a community-based survey in Metro Cebu, Philippines. Consistent with findings from other studies, adolescents in this sample were more socioeconomically disadvantaged, had poorer nutritional status during pregnancy, and received less prenatal care than adults. Bivariate analyses showed that infants of adolescents had a lower mean birthweight and were more at risk of low birthweight compared to those born to older mothers. When socioeconomic, biological, and behavioral risk factors were controlled for, young maternal age ceased to have an effect on birthweight in grams but remained a significant predictor of low birthweight. The common pathways through which maternal age influenced both birthweight variables were through its effects on maternal height and weight-for-height during pregnancy. In the model predicting birthweight in grams the maternal age effect was further manifested through prenatal care utilization.

Adolescent↗
PubMed2006

Racial disparities in low birthweight and the contribution of residential segregation: a multilevel analysis.

This study investigates the geography of racial disparities in low birthweight in New York City by focusing on racial residential segregation and its effect on the risk of low birthweight among African-American infants and mothers. This cross-sectional multilevel analysis uses birth records at the individual level (n=96,882) and racial isolation indices at the census tract or neighborhood level (n=2095) to measure their independent and cross-level effects on low birthweight. This study found that residential segregation and neighborhood poverty operate at different scales to increase the risk of low birthweight. At the neighborhood scale residential segregation is positively and significantly associated with low birthweight, after controlling for individual-level risk factors and neighborhood poverty. Residential segregation explains neighborhood variation in low birthweight means and race effects across census tracts, which cannot be accounted for by neighborhood poverty alone. At the individual scale-increasing levels of residential segregation does not significantly reduce or exacerbate individual-level risk factors for low birthweight; whereas increasing levels of neighborhood poverty significantly eliminates the race effect and reduces the protective effect of being foreign-born on low birthweight, after controlling for other individual-level risk factors and residential segregation. These findings are contradictory to previous health research that shows protective mechanisms associated with ethnic density in local areas. It is likely that structural factors underlying residential segregation, i.e., racial isolation, impose additional stressors on African-American women that may offset or disguise positive attributes associated with ethnic density. However, as poverty is concentrated within these neighborhoods, differences between races in low birthweight cease to exist. This study demonstrates that residential segregation and neighborhood poverty are important determinants of racial disparity in low birthweight in New York City.

Black or African American↗
PubMed1996

Birthweight, adult risk factors and incident coronary heart disease: the Caerphilly Study.

OBJECTIVE: To determine the relationships between birthweight, the incidence of coronary heart disease, and a range of coronary heart disease risk factors that operate during adult life. DESIGN: Cohort study with a 10-year follow-up period. SETTING: The town of Caerphilly, South Wales, and five adjacent villages. SUBJECTS: 1,258 men aged 45-59 at time of recruitment between 1979 and 1983. MAIN OUTCOME MEASURES: All deaths, coronary heart disease deaths, non-fatal CHD events. RESULTS: The validity of the birthweight data was supported by the strong graded associations between birthweight and anthropometric measures in adulthood, particularly height, body mass index, triceps, skinfold thickness and percentage body fat. An inverse relationship was found between birthweight and incident fatal and non-fatal CHD, (P = 0.01), though no relationship was found between birthweight and all-cause mortality. Amongst the major CHD risk factors, only fibrinogen shows a statistically significant relationship with birthweight (P = 0.008), fibrinogen levels being lower among the men with lower birthweights. When social and biological variables are included in models relating incident CHD and birthweight, the relationship between birthweight and incident fatal and non-fatal CHD remains essentially unchanged. CONCLUSION: A graded association between low birthweight and later CHD has been demonstrated in this cohort. This inverse association cannot be explained by the measured social or behavioural variables, or by other risk factors operating in adult life.

Birth Weight↗
PubMed2001

Birthweight and aerobic fitness in adolescents: the Northern Ireland Young Hearts Project.

The purpose of this study was to examine relationships between aerobic fitness and birthweight in adolescents. A representative cohort of 1015 males and females aged 12 and 15 y was studied, at baseline, with 89% of the 12-y-olds being re-examined 3 y later. The main outcome measures were an index of aerobic fitness, measured in laps completed at voluntary exhaustion by a twenty-metre shuttle run test, and recorded birthweight. Multiple linear regression, with and without adjustment for known and potential confounding variables, was performed to examine associations between fitness and birthweight. Birthweight and aerobic fitness were positively related so that for each kg decrease in birthweight, there was a mean (95% confidence interval) decrease in fitness score of 4.84 (0.35 to 9.33) laps and 3.21 (0.32 to 6.10) laps, in 12-y-old boys and girls respectively. This relationship is of a similar order to the strength of association between birthweight and adult blood pressure previously reported. Associations between birthweight and physical fitness at the age of 15 were weaker and were not significant. Our findings suggest that aerobic fitness may be involved in mediating the association between birthweight and cardiovascular disease risk later in life. The weakening of the association between birthweight and fitness between the ages of 12 and 15 y is similar to the weaker associations between birthweight and blood pressure seen among adolescents compared to younger children. We are currently re-examining this cohort to see if, as with blood pressure, the association with fitness re-emerges at an older age.

Adolescent↗
PubMed2000

Low birthweight and metabolic abnormalities in twins with increased susceptibility to Type 2 diabetes mellitus.

AIMS: To evaluate the role of environmental intra-uterine factors in determining the birthweights of twins with increased susceptibility to diabetes and discordant for abnormal responses to the oral glucose tolerance test (OGTT) and verify the possible association of within-pair birthweight differences and metabolic abnormalities in adult life. METHODS: Forty-six monozygotic (MZ) and 32 dizygotic (DZ) twins were enrolled; 13 MZ twins were discordant for impaired glucose tolerance (IGT) and/or hyperinsulinaemia compared to their co-twins. RESULTS: The 13 MZ discordant twins showed significantly lower birthweights than their normal co-twins (P < 0.001). When dividing all twins in those with the highest birthweights within the couple and those with the lowest, all subjects with abnormal OGTT were found in the latter group (P < 0.0001). Within-pair birthweight difference was significantly higher in MZ twins with abnormal OGTT and the metabolic syndrome compared to normal MZ twins. The relative risk of developing the metabolic syndrome was 8.7 (1.6-46.9) when comparing the higher tertile of within-pair birthweight differences (> or = 0.450 kg) to the two lower tertiles (< 0.450 kg). Logistic regression analysis confirmed within-pair birthweight difference as a significant predictor of abnormal responses to the OGTT and the metabolic syndrome. CONCLUSIONS: These data suggest a causative role for environmental intrauterine factors on the determination of birthweight and support the hypothesis that within-pair birthweight difference, rather than an absolute low birthweight, is responsible for the metabolic abnormalities in the adult life.

Adult↗
PubMed1999

The influence of prematurity and low birthweight on transplacental antibody transfer in Sri Lanka.

The influence of gestational age, the neonate's birthweight, and maternal age, weight, height and parity on transplacental antibody transfer was assessed in 141 mothers from Sri Lanka and their neonates. Paired blood samples were collected from the mothers and the umbilical cords of the newborns. The sera separated from these samples were categorized as: preterm but adequate birthweight (< 37 weeks' gestation and birthweight > or = 2500 g); term but low birthweight (> or = 37 weeks' gestation and birthweight < 2500 g); or term and adequate birthweight (> or = 37 weeks' gestation and birthweight > or = 2500 g). Neonatal and maternal sera were assessed, in ELISA, for specific IgG antibodies against measles virus (MeV), herpes simplex virus type-1 (HSV1), respiratory syncytial virus (RSV), varicella-zoster virus (VZV), tetanus toxoid (TT), diphtheria toxoid (DT), and Streptococcus pneumoniae (Pn) and Haemophilus influenzae type-b (Hib) capsular antigens. Placental antibody transfer to certain antibody specificities was significantly lower in preterm neonates than term neonates. Thus the ratios between geometric mean cord antibody levels and geometric mean maternal antibody levels (the antibody-transfer ratios) were lower in preterm sera than term sera, for MeV (1.51 v. 2.03; P = 0.03), HSV1 (1.29 v. 1.76; P = 0.04), VZV (0.96 v. 2.50; P = 0.01), TT (1.13 v. 1.33; P = 0.04), DT (1.03 v. 2.39; P = 0.02), Pn (0.68 v. 0.98; P = 0.01) and Hib (0.58 v. 0.98; P = 0.00). Geometric mean levels of antibody to MeV, VZV, TT, DT and Pn were also significantly lower in preterm neonates than term. Compared with the values for 'adequate-birthweight' sera, low birthweight was independently associated with significantly lower levels of antibody transfer, for MeV (with antibody-transfer ratios of 1.51 v. 2.03; P = 0.02), VZV (0.99 v. 2.50; P = 0.03), TT (1.01 v. 1.33; P = 0.04) and DT (1.16 v. 2.39; P = 0.04) and significantly lower levels of antibodies to MeV, HSV1, VZV, TT, DT and Pn in the neonates. Maternal age, weight, height and parity had no independent influence on placental IgG transfer for antibodies to any of the pathogens investigated. These results demonstrate that prematurity and low birthweight may influence the level of maternally acquired immunity in Sri Lankan neonates.

Antibodies, Bacterial↗
PubMed1987

Mothers remember birthweights of adolescent children: the Muscatine Ponderosity Family Study.

The mothers of 127 adolescents living in Muscatine, Iowa were asked at the time of a clinic examination to recall their child's birthweight in pounds and ounces. For comparison, the hospital-recorded birthweight was obtained for each child. On the average, mothers underreported their child's birthweight by 1.3 oz. Sixty of 127 (47%) mother-reported birthweights were the same as those from hospital delivery records; 12% of the mothers overreported the birthweight by at least 5 oz and 17% underreported by at least that amount. The age of the mother and number of biological children were related to the ability to recall the birthweight exactly. The mean age of the children, and thus the average length of the mother's recall, was 16.1 years. Neither the length of recall, nor the mother's education, her current body size, or the current body size of the child were related to recall ability. However, mothers who overreported their child's birthweight were significantly shorter and lighter and their children tended to be taller and heavier, when compared to the mothers who underreported and their children. When the degree of agreement found in our study between reported and recorded birthweight exists, the effect of using reported rather than recorded birthweights in an epidemiological investigation is sufficiently small to allow inferences to be made regarding the relationship between birthweight and body size at mid-adolescence.

Adolescent↗
PubMed1994

Maternal recall of birthweights of adult children: validation by hospital and well baby clinic records.

BACKGROUND: Several studies have suggested that maternal recall of offspring birthweight compares well to data from birth certificates or medical records. However, these studies describe relatively short recall periods and pertain to populations where hospitalized childbirth is the norm. Accuracy of maternal recall has not been confirmed after long recall periods or in populations where non-hospitalized childbirth is common. METHODS: Accuracy of recalled birthweights is assessed among 626 women interviewed at an average age of 43.3 years (standard deviation [SD] 1 year), at which time the average age of their 1297 offspring was 17.9 years (range 1-29 years, SD 4.8 years). One-third of these infants were delivered at home. Recalled birthweight was compared to hospital or Well Baby clinic records, available for 66% (861/1297) of all births. RESULTS: Record availability was not related to birthweight. For the 861 infants for whom both sources were available mean recorded birthweight was 3342 g (SD 586 g) and mean recalled birthweight 3340 g (SD 675 g). Recalled weights overestimated recorded weights by 109 g (95% Cl: 68-151) among infants weighing > 3750 g and underestimated recorded weights by 83 g (95% Cl: 54-111) among infants weighing < or = 3250 g. CONCLUSIONS: As an outcome variable recalled birthweights were unbiased, but less precise than recorded birthweights. Use of recalled birthweight does not sacrifice study power however and may increase generalizability provided recalled weights are available for 30% more infants than recorded weights. For individual birthweight assessment and for use as an independent variable recalled weights are biased and may have to be adjusted using recorded data as available.

Adult↗
PubMed1998

Maternal cotinine level during pregnancy and birthweight for gestational age.

BACKGROUND: Recent studies have found that cotinine is a better predictor of birthweight than the number of cigarettes smoked in pregnancy. In this paper we test this hypothesis and use cotinine to explore the effect of environmental tobacco smoke (ETS) on birthweight. METHODS: In all, 1254 white women were interviewed at booking, 28 and 36 weeks about the number and brand of cigarette smoked. Cotinine was assayed from blood samples taken on the day of interview. The outcome was birthweight for gestational age. RESULTS: There was good agreement between self-reported smoker/non-smoker status and maternal cotinine with 1.3% women mis-reported as non-smokers at booking, 0.6% and 1.8% mis-reported at 28 and 36 weeks respectively. Among smokers, cotinine was more closely related to birthweight than the number of cigarettes smoked at all three time points (r = -0.25 versus r = -0.16 at booking). A reduction in cotinine between booking and 28 weeks was associated with increased birthweight but the effect was not statistically significant. Among non-smokers the association between birthweight and cotinine was not statistically significant after adjusting for maternal height, parity, sex and gestational age. Difference in mean birthweight between non-smokers in the lower and upper quintiles of cotinine was 0.2% (95% CI: -2.4, 2.8). Pooling the results of 10 studies plus our own gave an estimated difference in mean birthweight between women unexposed and exposed to passive smoke of 31 g (95% CI: 19, 44). CONCLUSIONS: Cotinine is a better predictor of birthweight than the reported number of cigarettes smoked. If biochemical analysis is impossible, then self-reported smoking habit should be obtained prospectively using a structured approach. Any effect on birthweight of maternal passive smoking during pregnancy is small compared with the effects of maternal active smoking.

Adult↗
PubMed1995

Which birthweight groups contributed most to the overall reduction in the neonatal mortality rate in the United States from 1960 to 1986?

We determined the relative contributions of individual birthweight groups to the reduction in neonatal mortality rate (NMR) of US singleton livebirths from 1960 to 1986, the period during which neonatal intensive care was introduced and became established. Changes in the NMR for each race (non-white/white) and birthweight group were assessed in terms of three components of NMR (1) birthweight-specific neonatal mortality rate (BWS-NMR), (2) birthweight distribution, and (3) the interaction resulting from simultaneous changes in BWS-NMR and birthweight distribution. Overall, NMR decreased from 16.7 per 1000 livebirths in 1960 to 5.5 per 1000 livebirths in 1986. This reduction was achieved mainly by improvements in the BWS-NMRs of all birthweight groups. Neonates who weighted > 1.5 kg at birth were the major contributors to the overall reduction in the NMR; approximately two-thirds of total reduction in NMR between 1960 and 1980 and 52.6% of the total reduction between 1980 and 1986 occurred in the > 1.5 kg birthweight groups. Our study demonstrates that with the introduction of neonatal intensive care, survival of infants with birthweights > 1.5 kg improved markedly and that this improvement accounted for most of the decline in the neonatal mortality rate in the United States from 1960 to 1986. Therefore, in measuring the effectiveness of neonatal intensive care, the assessment should include not only very low birthweight (< 1.5 kg) but all birthweight groups.

Birth Weight↗
PubMed2005

Changing patterns of inequality in birthweight and its determinants: a population-based study, Scotland 1980-2000.

Birthweight is used as an indicator of individual and population health and is known to be strongly correlated with adult cardiovascular disease. This paper uses routinely collected maternity discharge data from Scotland between 1980 and 2000 to look at birthweight trends and the changes in the distribution of maternal risk factors for birthweight. We also examine the contributions of each of the risk factors to birthweight trends and investigate whether there has been a reduction in inequality in birthweight over time. Data from 1,282,172 singleton live births were used in the analysis. Both mean birthweight and low birthweight (LBW:<2500 g) were used as outcomes. The risk factors studied were maternal age, parity, maternal height, marital status and occupational social class of the father. The slope and relative indices of inequality were used to measure the change in inequalities over time. Mean birthweight increased from 3320 g in 1980 to 3410 g in 2000, while the percentage LBW decreased slightly from 5.7% in 1980 to 5.4% in 2000. The prevalence of many risk factors changed; there has been an increase in the proportion of older mothers, single mothers, taller mothers and mothers with undetermined social class. Although most risk factors had a significant change in effect over time, the inequalities in birthweight between groups did not appear to diminish over time. Both the slope and relative index of inequality had a quadratic relationship over time, with the inequalities in birthweight being greatest in the early 1980s and late 1990s.

Adult↗
PubMed2005

A feeling of well-being accompanied by a period of prosperity and birthweight in Chile: a possible link?

The aims of the study were to describe the trend in birthweight from 1985 to 2000 in Chile and ascertain the possible factors that may explain the changes in birthweight during the period. We used time series of birthweight and length at birth of all live births (n > 4,000,000). Multivariable regression analyses were carried out to assess whether the gender of the newborn, maternal education, maternal age and marital status could explain the trend in the total time series and by period. Birthweight adjusted for gestational age was analysed in terms of grams and Z scores. There was an increase in birthweight of 100 g between 1989 and 1994 that coincided with the re-establishment of democracy and economic growth in Chile. The changes in birthweight were not explained by the available independent variables and trends of caesarean section, maternal obesity and post-mature deliveries over the period. The birthweight difference between mothers with university education and those with primary education was 0.2 Z scores (equivalent to 110 g) in 1985 and was greatly reduced by 2000 (equivalent to 40 g). A positive sense of social well-being and economic growth may have influenced an increase in birthweight between 1989 and 1994 as socio-economic growth preceded and continued after the period of increasing birthweight. Our study showed a remarkable decrease in the differences in birthweight by educational level not shown in other countries of similar wealth.

Adolescent↗
PubMed2006

Bacterial vaginosis in a cohort of Danish pregnant women: prevalence and relationship with preterm delivery, low birthweight and perinatal infections.

OBJECTIVE: To determine the prevalence of bacterial vaginosis (BV) in the second trimester of pregnancy in a Danish population using the Schmidt criteria and to examine whether BV was associated with subsequent preterm delivery, low birthweight or perinatal infections. DESIGN: Prospective cohort study. SETTING: Department of Obstetrics and Gynaecology at a University Hospital, Denmark. POPULATION: Three thousand five hundred and forty pregnant women aged 18 years or more. METHODS: A smear from the vagina was obtained from all women, air-dried and stored for subsequent diagnosis of BV. After rehydration with isotonic saline, the smear was examined in a phase-contrast microscope at 400x, and the numbers of lactobacilli morphotypes and small bacterial morphotypes were counted. A score for BV was calculated according to the method described by Schmidt. The outcome of pregnancy from 20 weeks of gestation was examined in the 3262 singleton pregnant women who were included in this study before 20 weeks of gestation. The relationship between BV and adverse outcome of pregnancy was examined by univariate and multivariate analyses. MAIN OUTCOME MEASURES: Prevalence of BV, preterm delivery (<37 weeks), low birthweight (<2500 g), preterm delivery of a low-birthweight infant and clinical chorioamnionitis. RESULTS: The prevalence of BV was 16%, and the rate of preterm delivery was 5.2% in the study population of 3262 singleton pregnant women who were included before 20 weeks of gestation. Mean birthweight was significantly lower in infants of women with BV than in infants of women without BV (3408 versus 3511 g, P < 0.01). Univariate analyses showed that BV was marginally associated with preterm delivery but significantly associated with low birthweight, preterm delivery of a low birthweight infant, indicated preterm delivery and clinical chorioamnionitis. Multivariate analyses, which adjusted for previous miscarriage, previous preterm delivery, previous conisation, smoking, gestational diabetes, fetal death and preterm premature rupture of membranes, showed that BV was significantly associated with low birthweight (OR 1.95, 95% CI 1.3-2.9), preterm delivery of a low-birthweight infant (OR 2.5, 95% CI 1.6-3.9), indicated preterm delivery (OR 2.4, 95% CI 1.4-4.1) and clinical chorioamnionitis (OR 2.7, 95% CI 1.4-5.1). CONCLUSIONS: The prevalence of BV determined using the Schmidt criteria in the early second trimester of pregnancy was similar to that found in similar studies. The presence of BV before 20 weeks of gestation was an independent risk factor for delivery of an infant with low birthweight, preterm delivery of a low-birthweight infant, indicated preterm delivery and clinical chorioamnionitis.

Cohort Studies↗
PubMed2000

Development of a customised birthweight standard for ethnic Chinese subjects.

A model to establish customised birthweight standards for the Chinese population was developed, using data from a cohort of 1564 Chinese women with normal singleton pregnancies. Multiple regression analysis was performed using maternal height, weight, parity, gestation at delivery and fetal sex as independent (predictor) variables. From this, a customised ideal birthweight for each baby can be estimated, and the normality of the actual birthweight can be evaluated according to this, rather than from population standards. The results of this study show that birthweights are strongly influenced by maternal characteristics, confirming conclusions from similar studies in other ethnic populations. The overall mean birthweight at 280 days of gestation was 3252 g, which was smaller than that of the Caucasian population. Birthweight increased with maternal height (5.1 g/cm), maternal booking weight (10.2 g/kg) and gestation at delivery (18.3 g/day from 280 days). Babies from women who had two previous deliveries weighed 145.2 g more than the nulliparous. Male babies were 84.8 g heavier than females. Adjustment using these results produces a customised ideal birthweight for each baby. When compared with population based standards, customised birthweight standards identified significantly fewer small for gestational age (SGA - birthweight below 10th centile, McNemar Chi square = 19.1, p < 0.01) and fewer large for gestational age (LGA - birthweight above 90th centile, McNemar Chi square = 23.7, p < 0.01) cases.

Asian People↗
PubMed1983

Normal ranges of T4 screening values in low birthweight infants.

Thyroxine (T4) screening values in infants of low birthweight in relation to birthweight and gestational age are reported. There were 86 healthy infants of low birthweight (group 1), and 29 preterm infants with respiratory distress syndrome (group 2). All the group 2 infants and 36% of those in group 1 had a T4 screening value below the cut-off point (-2.1 SD). In group 1 there was a significant increase in T4 with birthweight at a given gestational age, as well as with gestational age at a given birthweight. In group 2 there was also a significant increase in T4 values in relation to birthweight and gestational age, but it could not be ascertained whether this increase existed at a given gestational age or birthweight. A statistical model giving normal ranges of T4 for both groups of infants is presented, which, if applied to low birthweight infants, makes it possible to estimate the effect of low birthweight on T4 screening values, provided the birthweight and gestational age are known. In this manner the sensitivity of screening for congenital hypothyroidism is enhanced and the recall rate reduced.

Birth Weight↗