Birthweight, socio-economic status and growth of Brazilian infants

A population-based cohort of 1458 Brazilian infants was followed from birth to 9-15 months of age to investigate the effects of birthweight and family income on subsequent growth. There was a strong association between birthweight and attained weight and length, while virtually no malnutrition among children who weighed more than 3000 g at birth; Children with lower birthweights tended to put on less weight during the first year, but these differences were no longer significant after controlling for family income. As a result, infants of lower birthweights tended to remain behind those of higher birthweights. Children from the wealthiest families gained 20% more weight than low-income infants, irrespective of birthweight. Low birthweight infants from high-income families were therefore likely to approach the standard weight at one year old while those from poor families lagged behind.     

Maternal height,pregnancy weight gain,and birthweight

The Institute of Medicine recommends that short women gain less weight during pregnancy than taller women in order to reduce the risk of high birthweight, which can lead to feto-pelvic disproportion. This recommendation, however, is based on clinical judgment rather than on epidemiologic evidence, as few studies have examined the relationships between maternal height, pregnancy weight gain, and infant birthweight. Our objective was to determine whether maternal height is an independent risk factor for infant birthweight and to assess whether maternal height modifies the effect of pregnancy weight gain on infant birthweight. We examined the relationship between maternal height and infant birthweight in a multi-ethnic cohort of 8,870 women with uncomplicated pregnancies who delivered singleton infants at the University of California, San Francisco, 1980–1990. Using multiple linear regression, we modeled the contribution of height and weight gain to birthweight in four different ethnic groups. Increasing maternal height was significantly and positively associated with infant birthweight in White, Black, and Asian women, but not Hispanic women. The relationship between pregnancy weight gain and infant birthweight was not modified by maternal height. Am. J. Hum. Biol. 12:682–687, 2000. © 2000 Wiley-Liss, Inc.     

Factors affecting birthweight of rural Australian Aborigines

AIM: To examine factors affecting birthweight of Aboriginal infants in the Kimberley region of north-west Australia. Research design: A retrospective study of maternal and infant health records obtained through routine data collection. Subjects and methods: Birthweight and length of 2959 infants born to 1822 women from 1986 to 1994 were analysed. Mothers and infants were matched using unique identification codes. Index births and subsequent births to the same mother were collated in order to examine relative birth order effects and to calculate birth intervals. RESULTS: Regression analysis showed significant associations between weight of the index birth and maternal age (p < 0.001), remoteness of locality (p < 0.01), sex of the infant (p < 0.001) and maternal height (p < 0.001). Length at birth was significantly associated with ethnicity of infant (Aboriginal vs Aboriginal/non-Aboriginal admixture, p < 0.05), sex (p < 0.001), remoteness (p < 0.01) and maternal height (p < 0.001). Similar associations were observed for second and subsequent births. Birth interval was not associated with birthweight or length. Low birthweight was also more common to Aboriginal mothers compared with mothers of Aboriginal/non-Aboriginal admixture (13.1% vs 9.2%; chi(2) = 5.1, p < 0.025) even though there were no differences in height between these two groups. Teenage mothers (< or =19 years) were no more likely to have low birthweight babies than older mothers. Of the variables examined, the only significant predictor of low birthweight was a previous low birthweight baby (relative risk = 4.45, p < 0.001). CONCLUSIONS: Short birth intervals and teenage births were not significant contributors to low birthweight in the present study. The high prevalence and duration of breastfeeding in the Kimberley may contribute to long average birth intervals. Pre-term birth, rather than intrauterine growth retardation, is likely to be the most common cause of low birthweight in this population.     

Factors affecting birthweight of rural Australian Aborigines

Aim : To examine factors affecting birthweight of Aboriginal infants in the Kimberley region of north-west Australia. Research design : A retrospective study of maternal and infant health records obtained through routine data collection. Subjects and methods : Birthweight and length of 2959 infants born to 1822 women from 1986 to 1994 were analysed. Mothers and infants were matched using unique identification codes. Index births and subsequent births to the same mother were collated in order to examine relative birth order effects and to calculate birth intervals. Results : Regression analysis showed significant associations between weight of the index birth and maternal age ( p < 0.001), remoteness of locality ( p < 0.01), sex of the infant ( p < 0.001) and maternal height ( p < 0.001). Length at birth was significantly associated with ethnicity of infant (Aboriginal vs Aboriginal/non-Aboriginal admixture, p < 0.05), sex ( p < 0.001), remoteness ( p < 0.01) and maternal height ( p < 0.001). Similar associations were observed for second and subsequent births. Birth interval was not associated with birthweight or length. Low birthweight was also more common to Aboriginal mothers compared with mothers of Aboriginal/non-Aboriginal admixture (13.1% vs 9.2%; &#104 2 = 5.1, p < 0.025) even though there were no differences in height between these two groups. Teenage mothers ( &#114 19 years) were no more likely to have low birthweight babies than older mothers. Of the variables examined, the only significant predictor of low birthweight was a previous low birthweight baby (relative risk = 4.45, p < 0.001). Conclusions : Short birth intervals and teenage births were not significant contributors to low birthweight in the present study. The high prevalence and duration of breastfeeding in the Kimberley may contribute to long average birth intervals. Pre-term birth, rather than intrauterine growth retardation, is likely to be the most common cause of low birthweight in this population.     

The effect of maternal nutritional variables on birthweight outcomes of infants born to Sherpa women at low and high altitudes in Nepal

A prospective, longitudinal study was conducted in Nepal to investigate the effects of maternal nutrition on the pregnancy outcome of Sherpa women living at low and high altitudes. It was hypothesized that variation in nutrition and energy expenditure of pregnant women would correlate with variation in infant birthweight. Anthropometric dimensions, energy consumption and expenditure, and demographic and migration information were collected on a large sample of women living in two regions of Nepal: the Khumbu region (3480–3930 m) and Kathmandu (1330 m). This paper reports findings for a subset of the sample; 17 women at low altitude and 21 women at high altitude who became pregnant and were followed during pregnancy. The results showed no significant differences for mean birthweights between the low (X = 3069 ± 341 grams) and high (X = 3099 ± 483 grams) altitude samples. Furthermore, larger birthweights were associated with larger weight gains during pregnancy for the high altitude sample. A stepwise regression analysis found a negative association between high energy expenditures during the second trimester and infant birthweight, but positive associations were found between third trimester calcium and second trimester protein intakes and birthweight. Prepregnancy BMI and stature were associated positively with infant birthweight, suggesting that good nutritional status prior to pregnancy may play an important role in pregnancy outcome for this population. Am. J. Hum. Biol. 9:751–763, 1997. © 1997 Wiley-Liss, Inc.     

Birth dimensions in Melanesian and Indian Fijians and their relationships with maternal and socio-economic factors

Fifty-nine Melanesian (MF) and 39 Indian (IF) Fijian full-term newborns were studied within 5 days of birth. Dimensions recorded included birthweight, length, crown-rump length, head circumference, upper limb length, bycondylar humeral and femoral diameters and four skinfolds (triceps, subscapular, suprailiac and thigh). Data from previous pregnancies of the presenting newborns' mothers were added to presenting birthweights, giving a total of 160 MF and 84 IF birthweights. In all birthweight and linear dimensions MFs were the bigger. Sex differences were significant in respect only of head circumference and the two bicondylar diameters. Multiple regression analysis showed dimensions in MF newborns to have few significant relationships with the maternal and socio-economic variables of age, parity, stature and years of education, but IFs had many more significant relationships. When covariance correction was made for the significant maternal and socio-economic variables (maternal age and parity) little effect on racial differences was seen. All linear dimensions except length could be subsumed into birthweight. MFs had greater triceps and subscapular skinfold thicknesses than IFs, a difference which was not much changed by covariance correction for significant maternal and socio-economic variables (maternal stature and years of education). Measurements of shape, expressed as ratios of linear dimensions, showed few racial differences but males had relatively broader limbs. For upper limb shape only, this difference was maintained after covariance correction for significant maternal and socio-economic variables (parity, stature and education). The greater size of MF infants at birth is associated with lower peri- and neonatal death rates. However this advantage is reversed during the remainder of the first year of life. It is suggested that better standards of infant care among IFs are responsible for this change.     

Differential effect of ecologic risk factors on the low birthweight components of African-American, Mexican-American, and non-Latino white infants in Chicago.

This study explored the relationship between ecologic risk factors and infant birthweight. A stratified analysis was performed on all African-American, Mexican-American, and white infants born in Chicago in 1990. One half of African-American mothers (n = 26,799) resided in communities with multiple ecologic risk factors, yet their very low birthweight rates were unaffected by the number of these factors. By contrast, only 5% of Mexican-American mothers (n = 9913) and 5% of white mothers (n = 13,596) lived in communities with multiple ecologic risk factors. Their very low birthweights were twice that of infants born to mothers who resided in communities with no ecologic risk factors. These results indicate that ecologic risk factors affect the very low birthweight rates of Mexican Americans and whites but not African Americans.     

Gestational age, birthweight, and neonatal mortality for extremely premature inner-city African-American and Latino infants.

This article analyzes birthweight, gestational age, and inhospital survival for 233 extremely premature infants born at an inner-city hospital over the past 5 years. Results for gestation-specific birthweights and survival did not differ between inner-city Hispanic and African-American infants born at 24 to 28 weeks of gestation. For infants with gestation of 23 to 28 weeks, weight at birth increased by approximately 100 g/week gestation. Survival rates increased from 15% at 23 weeks to 75% by 28 weeks gestation. Survival in this sample was strongly affected by respiratory distress syndrome, air leak, and birthweight. Prenatal steroids administered to the mother had a significant effect on improving survival using univariate analysis and was at the limits of statistical significance using logistic regression. Other maternal, obstetric, and neonatal factors had little or no effects on survival in this group of very immature infants.     

Low birthweight in African Americans: does intergenerational well-being improve outcome?

The primary antecedent of infant mortality is low birthweight. Vital statistics data have shown that women of low socioeconomic status, regardless of race, are at greater risk for delivering low birthweight infants; however, prevailing data show that black women of the same socioeconomic status as white women have a twofold higher risk of giving birth to an infant weighing < 2500 g and a threefold risk of delivering a very low birthweight infant weighing < 1500 g. There is also evidence that intergenerational effects on birth outcome exist. However, virtually all studies of the effect of socioeconomic status on perinatal outcome have been cross-sectional; the effect of sustained intergenerational well-being has not been measured. To address this gap, this study was designed to demonstrate that in an African-American population with sustained high socioeconomic status and equal risk factors, the birthweight distribution and other reproductive outcomes are the same as those for comparable US white populations. Preliminary findings are reported here.     

Infant birthweight in the US: the role of preconception stressful life events and substance use

The purpose of this study was to determine the relationships among preconception stressful life events (PSLEs), women’s alcohol and tobacco use before and during pregnancy, and infant birthweight. Data were from the Early Childhood Longitudinal Study-Birth Cohort (n?=?9,350). Data were collected in 2001. Exposure to PSLEs was defined by indications of death of a parent, spouse, or previous live born child; divorce or marital separation; or fertility problems prior to conception. Survey data determined alcohol and tobacco usage during the 3 months prior to and in the final 3 months of pregnancy. We used staged multivariable logistic regression to estimate the effects of women’s substance use and PSLEs on the risk of having a very low (<1,500 g, VLBW) or low (1,500–2,499 g, LBW) birthweight infant, adjusting for confounders. Women who experienced any PSLE were more likely to give birth to VLBW infants (adjusted odds ratio [AOR]?=?1.35; 95 % confidence interval [CI]?=?1.10–1.66) than women who did not experience any PSLE. Compared to women who never smoked, women who smoked prior to conception (AOR?=?1.31; 95 % CI?=?1.04–1.66) or during their last trimester (AOR?=?1.98; 95 % CI?=?1.56–2.52) were more likely to give birth to LBW infants. PSLEs and women’s tobacco use before and during pregnancy are independent risk factors for having a lower birthweight baby. Interventions to improve birth outcomes may need to address women’s health and health behaviors in the preconception period.     

Ethnicity,birth weight,and maternal age in infant mortality: Hawaiian experience

To investigate the role of ethnicity, birth weight, and maternal age in infant mortality, separately in neonatal and postneonatal phases, this study used linked birth and infant death certificates for a 10-year period, 1979–1988, in the State of Hawaii. Log-linear analysis was applied to the cross-classified tables generated from the two files. Birth weight was a strong factor both in neonatal and postneonatal phases, but ethnicity was a factor only in the latter phase. Maternal age was not significant in infant survival in either phase, but it was strongly associated with the other two factors. Among the nine major ethnic groups residing in the state, black and Hawaiian women were more likely to have infants dying during the postneonatal period. © 1993 Wiley-Liss, Inc.     

Residential racial concentration and birth outcomes by nativity: do neighbors matter?

OBJECTIVES: We examined the associations of residential segregation with poor birth outcomes (low birthweight, preterm) and with perinatal risk markers (maternal age, education and marital status, prenatal care and substance use, presence of paternal information on birth certificate) for foreign- and native-born black women in the Minnesota seven-county metropolitan area. METHODS: Data were from 1990-1999 Minnesota birth certificates linked to the 1990 U.S. census. We used multivariable logistic regression to examine the association of perinatal risk markers, low birthweight and preterm birth for foreign- and native-born black women by residential black concentration. RESULTS: Native-born black women had a higher prevalence of risk markers and were at almost 1.5 times the risk of foreign-born blacks for delivery of low-birthweight or preterm infants. Risk markers and poor birth outcomes were most prevalent in medium and high-black-concentration areas than low-concentration areas. Preterm birth was slightly positively associated with residential black concentration. CONCLUSIONS: Native-born black women were at higher risk than foreign-born women for delivery of preterm and low-birthweight infants. Residential black concentration was associated with risk markers and only slightly associated with preterm birth. Further study of why birth outcome differentials exist by nativity and residential black concentration may identify opportunities for community-based public health interventions.     

Low maternal serum concentrations of mannose‐binding lectin are associated with the risk of shorter duration of pregnancy and lower birthweight

Chronic inflammation has been implicated as the underlying mechanism responsible for the pathophysiology of preterm labour. Mannose‐binding lectin (MBL) plays a central role in the innate immune response and is thus an important component of the first line of defense. The aim of this study was to investigate whether serum concentrations of MBL correlated with the incidence of preterm birth and low birthweight in a cohort of women with signs of threatened preterm birth. A cohort of 60 patients who presented with regular contractions and/or short cervix (group A) between 24 and 32 weeks of gestation and 20 healthy controls (group B) who had no pregnancy complications and delivered at term were recruited into a prospective study. The following outcomes were recorded: presence of preterm labour and birthweight in all patients. MBL and high sensitivity C‐reactive protein levels were measured in all serum samples. The serum concentrations of MBL were significantly reduced in patients with threatened preterm labour (Group A), compared to the control Group B. Furthermore, infants born to Group A mothers with MBL deficiency (n = 13, MBL ≤100 ng/mL) had significantly lower birthweights, compared to those born to Group A women with normal MBL serum concentrations (P  < .0001). Our small cohort study demonstrated a strong association between MBL deficiency and preterm delivery, and associated low birthweight. MBL deficiency could thus be considered an important risk factor for preterm birth.     

Variability of gestational age distributions by sex and ethnicity: An analysis using mixture models

As an antecedent of birthweight and in its own right, gestational age is an important proximate determinant of infant mortality. Recent analyses using mixture models of birthweight distributions suggest that substantial heterogeneity occurs within a birth cohort even when controlling for sex and ethnicity. This article extends the mixture model analysis to gestational age. The results indicate that, like birthweight, human gestational age distributions are heterogeneous, consisting of two, or perhaps more, subpopulations with separate means and variances. The possibility that birthweight and gestational age both identify the same underlying subpopulations cannot be rejected. Statistical analyses of the sex and ethnic differences indicate that, like birthweight, gestational age distributions vary significantly between the sexes and among ethnic groups. However, the pattern, and even the direction, of the variation often differs between the two indicators of birth outcome. The results suggest that a multivariate mixture model that combines birthweight and gestational age might be a useful extension of the univariate mixture models. Am. J. Hum. Biol. 12:181–191, 2000. © 2000 Wiley-Liss, Inc.     

Ethnic variation in the size of infant at birth

The impact of ethnicity and other maternal factors (BMI, parity, glucose tolerance, gestational age) on the size of the infant at birth was investigated in a relatively low socioeconomic status, multi-ethnic population at San Francisco General Hospital. A sample of 2,069 infants born to mothers of black, non-Hispanic white, Hispanic, and Chinese descent and whose mothers had received prenatal care at San Francisco General Hospital were studied. Maternal size, pregnancy history, and blood glucose were determined prenatally at 26–28 weeks gestation. Anthropometry was performed on the infant within 72 hours of birth. Black and Chinese infants were the lightest in weight, while Hispanic infants were the heaviest. When correction was made for maternal factors black infants were shown to be significantly (P < .05) lighter in birth weight than non-Hispanic white, Chinese, or Hispanic infants. Black infants were also significantly shorter in birth length and smaller in chest circumference. Chinese infants had significantly (P < .05) greater adiposity, as indicated by the sum of skinfold measurements, than both black and Hispanic infants. These findings are relevant to current practices in neonatal growth categories which are determined solely by birth weight and do not account for variations in body composition. Comparisons with a relatively higher socioeconomic status sample from Kaiser-Permanente Hospital (Oakland) shows a similar prevalence of low birth weight among blacks. These results support other results that ethnicity is a major independent influence on the weight of the newborn.     

Maternal factors, birthweight, and racial differences in infant mortality: a Georgia population-based study.

Black infant mortality rates (IMRs) are approximately twice those of whites in Georgia and nationwide. This study evaluates maternal factors, particularly marital status, that influence racial differences in infant mortality. Population-based data on 565,730 live births and 7269 infant deaths in Georgia from 1980 to 1985 were examined. The IMR ratio for unmarried compared to married mothers was calculated and adjusted singly for maternal education, age and race, and infant birthweight. In addition, racial differences in IMR were estimated using stratified analysis on the basis of four factors: infant birthweight, maternal age, marital status, and education. When only normal birthweight infants were considered, the IMR, adjusted for maternal education level, was highest for infants born to unmarried black teens (9.5/1000 live births), followed by that for infants born to married black teens (9.1), unmarried black adults (7.5), married black adults (4.8), married white teens (4.4), married white adults (3.4), unmarried white adults (2.4), and unmarried white teens (1.3). When only low birthweight infants were considered, the highest IMR per 1000 was found in infants born to married black adults (119), followed by unmarried black adults (103), married black teens (99.9), unmarried black teens (92.5), married white adults (92.1), married white teens (79.0), unmarried white adults (38.0), and unmarried white teens (26.3). These differences led to a black-to-white IMR risk ratio from 1.3 for low birthweight infants born to unmarried teen or adult mothers to 3.7 for normal birthweight infants born to unmarried teen mothers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Multifetal reduction of triplets to twins: a prospective comparison of pregnancy outcome

The aim of this study was to compare the outcome of triplets managed expectantly or by multifetal reduction to twins to assess the potential benefit of fetal reduction. The study design was prospective, comparative and monocentric and the study was conducted in a teaching hospital. Out of 148 women with triplets mostly obtained after infertility treatment, 83 were expectantly managed while 65 chose reduction to obtain twins. Main outcome measures were fetal loss before 24 weeks, premature deliveries before 28, 32 and 34 weeks, rate of low birthweight infants and neonatal and perinatal mortality rates. The fetal loss rate before 24 weeks did not differ between the ongoing group and the reduced group (6 versus 5.4%). Reducing triplets was associated with a significantly lower incidence of the following: prematurity before 28, 32 and 34 weeks (P < 0.001), low birthweight infants whose weights were under the third centile (P < 0.002) and infants whose weights were less than 1000, 1500 and 2000 g (P < 0.001). Neonatal (although apparently lower in the reduced group) and perinatal mortality did not significantly differ. Our results indicate that reduction of triplets to twins is effective to improve preterm birth and fetal growth.     

Fetal size in mid- and late pregnancy is related to infant alertness: the generation R study

The vulnerability for behavioral problems is partly shaped in fetal life. Numerous studies have related indicators of intrauterine growth, for example, birth weight and body size, to behavioral development. We investigated whether fetal size in mid- and late pregnancy is related to infant irritability and alertness. In a population-based birth cohort of 4,255 singleton full-term infants ultrasound measurements of fetal head and abdominal circumference in mid- and late pregnancy were performed. Infant irritability and alertness scores were obtained by the Mother and Baby Scales at 3 months and z-standardized. Multiple linear regression analyses revealed curvilinear associations (inverted J-shape) of measures of fetal size in both mid- and late pregnancy with infant alertness. Fetal size characteristics were not associated with infant irritability. These results suggest that alterations of intrauterine growth affecting infant alertness are already detectable from mid-pregnancy onwards.     

Prenatal exposure to valproic acid during pregnancy and limb deficiencies: A case‐control study

We conducted a case‐control study using data from the Spanish Collaborative Study of Congenital Malformations (ECEMC) on the relationship between prenatal exposure to valproic acid (VPA) and the presence of limb deficiencies in newborn infants. Among a total of 22,294 consecutive malformed infants (once we excluded genetic syndromes) and 21,937 control infants with specified data on antiepileptic drugs during gestation, 57 malformed infants and 10 control infants were exposed to VPA during the first trimester of pregnancy. Of the total of malformed infants exposed to VPA, 36.8% (21/57) presented with congenital limb defects of different types (including overlapping digits, talipes, clubfoot, clinodactyly, arachnodactyly, hip dislocation, pre‐ and postaxial polydactyly, etc.), three of them having limb deficiencies. The result of the case‐control analysis shows a risk for limb deficiencies of odds ratio = 6.17 [confidence interval (CI) 1.28–29.66, P = 0.023], after controlling for potential confounder factors. If we consider that in our population the prevalence at birth of this type of defect is 6.88 per 10,000 livebirths (95% CI 6.43–7.36) we can estimate that the risk for women treated with VPA of having a baby with limb deficiencies would be around 0.42%. The limb deficiencies in the three patients exposed to VPA were the following: the first case was a newborn infant with hypoplasia of the left hand, the second patient was a newborn infant with unilateral forearm defect and hypoplastic first metacarpal bone in the left hand, and the third patient presented with short hands with hypoplastic first metacarpal bone, absent and hypoplastic phalanges, retrognathia, facial asymmetry, hypospadias, teleangiectatic angioma in skull, and hypotonia. Am. J. Med. Genet. 90:376–381, 2000. © 2000 Wiley‐Liss, Inc.     

Secular trend in birthweight among the Purari delta population, Papua New Guinea

The aim of this analysis was to examine the extent and possible seasonal nature of the secular trend in mean birthweight in the Purari delta, Papua New Guinea. This is a country undergoing rapid modernization, and with this has come a secular trend toward increased adult body size in some parts of the country but not others. Birthweight data, collected by month of delivery at Kapuna Hospital in the Purari delta between the years 1969 and 1996, was analysed by year of birth and by season, using one-way analysis of variance and post hoc Scheffé tests with the statistical software SPSS-PC+. A total of 927 birthweights for the years 1969, 1972, 1977, 1994 and 1996 were included in the analysis. Twin births were excluded from analysis, as were births below 1.5 kg. There is clear evidence of a secular trend in increasing mean birthweight between the period 1969 and 1996, with the largest significant difference being between 1977 and 1994, from 2.70 to 2.92 kg. There were no significant differences in mean birthweight between the sexes. The rate of birthweight increase between 1977 and 1994 was 130 g per decade, lower than the gain of 200 g per decade in the period 1994-1996. The decline in birthweight of 90 g per decade during the period 1969-1977 is not statistically significant. The proportion of infants born with low birth weight (< 2.5 kg) shows an increase between 1969 and 1972, and a decline thereafter. While seasonal differences in birthweight during any of the years examined is non-significant, significantly greater mean birthweight across the period 1969-1996 was found for births during the wet season (April to July), and the drier season (August to November), respectively. The secular increase in mean birthweight is likely to be a consequence of the improvements in maternal diet and increased maternal body size that have come with economic modernization. The secular trend of seasonality in mean birthweight among the Purari delta population may be a function of seasonally varied displacement of traditional diet by non-local bought foods, as well as reduced seasonality of maternal workload associated with the processing of the traditional staple food.