Association of parental characteristics with adverse outcomes of adolescent pregnancy

BACKGROUND: It is well-known that pregnancy in adolescence has an increased risk of adverse reproductive outcomes. It remains unclear whether this association is due mainly to the unfavourable sociodemographic status or due solely to biological immaturity of pregnant adolescents. OBJECTIVE: The purpose of this study was to determine the association of parental sociodemographic characteristics with the adverse outcomes of adolescent pregnancy. METHOD: Data from certificates of live births in Taichung County, Taiwan in 1994 of 7994 singleton, first-born babies whose mothers were 15-34 years of age were analysed. The relative risk of having adverse pregnancy outcomes for adolescent subgroups was obtained as compared with that among mothers 20-34 years of age with the same characteristics. The adjusted relative risk of having adverse pregnancy outcomes for each covariate was calculated by a multiple logistic regression analysis. RESULTS: Of 7994 babies born to mothers of 15-34 years of age, 8.3% were born to adolescent mothers. In all age groups, the younger adolescent mothers (15-17 years of age) had the highest percentage of both infants with low birth weight (10.6%) and preterm births (7.1 %). Younger adolescent mothers in almost all sociodemographic categories had higher risks of having both low-birth-weight and preterm births than those of older adolescent mothers. Multiple logistic regression analysis showed that a younger maternal age is the only significant risk factor for having infants with low birth weight (adjusted RR = 2.5, 95% Cl 1.8-4.5 and adjusted RR = 1.7, 95% Cl 1.2-2.6 for younger and older adolescent mothers, respectively) or preterm birth (adjusted RR = 1.9, 95% Cl 1.1- 3.4 and adjusted RR = 1.5, 95% Cl 1.0-2.3 for younger and older adolescent mothers, respectively). CONCLUSIONS: Adolescent pregnancy carries an increased risk of having low-birth-weight and preterm births, and a younger maternal age is causally implicated.      

Birth weights of black African babies of migrant and nonmigrant mothers compared with those of babies of European mothers in Portugal

PURPOSE: The study aim is to investigate differences in birth weights between babies of foreign-born black African, Portugal-born black African, and Portugal-born white mothers. METHODS: Hospital records for Amadora and Sintra from July 2001 to June 2002 were collated and 2949 Portugal-born white, 461 Portugal-born black African, and 817 foreign-born black African live singleton babies were identified. The impact of biologic and social factors (infant sex, maternal age, parity, gestational age, and maternal smoking, education, and occupational class) and mode of delivery on birth weights was assessed by using multivariable regression models. RESULTS: African mothers were more likely to be of lower socioeconomic status than white Portuguese mothers, among whom rates of smoking were two to three times greater (21% among white Portuguese mothers). Small preterm babies comprised 1.5% of white Portuguese babies, 2.3% of babies of Portugal-born African mothers, and 3.9% of babies of foreign-born African mothers (p < 0.05 compared with white Portuguese babies). Compared with white Portuguese babies, mean birth weight of term babies, adjusted for sex, among Portugal-born African mothers was -24.6 g (95% confidence interval, -70.1-20.9), and among foreign-born African mothers, was +38.8 g (95% confidence interval, 2.9-74.8). Adjustment for parity, maternal age, and gestational age decreased the significant birth weight advantage of babies of foreign-born African mothers to +2.3 g (95% confidence interval, -31.9-36.5). Among nonsmokers, after adjusting for these factors, white Portuguese babies were heavier (40 g; p < 0.05) than babies of foreign-born African mothers, but among smokers, they were lighter (163 g; p < 0.05). CONCLUSIONS: Compared with white Portuguese babies, mean birth weight of term babies of foreign-born African mothers was greater, and that of babies of Portugal-born African mothers was intermediate. These differences were related to a combination of biologic factors and smoking.     

Decline in, and lack of difference between, average birth weights among African and Portuguese babies in Portugal

BACKGROUND: In preliminary data in Portugal, we found that African babies of migrant mothers were heavier than White Portuguese babies born in Lisbon. We investigate whether this pattern is replicated in the national data, and in addition the trends in birth weight in these groups. METHODS: DESIGN AND SETTING: Births registered between 1995 and 2002 classified by reported nationality of mothers. PARTICIPANTS: 849,595 Portuguese births ('Portuguese' nationality, predominantly of European descent) and 22,463 African births ('Angola', 'Cape Verde', or 'Guinea Bissau, Republic of Guinea or Equatorial Guinea' nationality, predominantly of African origin). RESULTS: Among Portuguese births, there was a decline in births to teenaged mothers and an increase to mothers aged >or=35 years, with >9 years of education or in a non-manual class, but among African births there was an increase in births to teenaged mothers and a decline to mothers from advantaged socioeconomic backgrounds. Using the Wilcox-Russell method, overall mean birth weights of term Portuguese (3,303, SD 424 g) and African (3297, SD 441 g) babies were not different but the percentage of small preterm births was higher among African (4.7%) than among Portuguese (2.9%) births. Between 1995 and 2002, mean birth weight of term Portuguese babies declined by 58 g (3,334-3,276 g) and of African babies by 57 g (3,341-3,284 g). The left shift of the birth weight distributions was independent of maternal age, parity, and social factors among Portuguese babies, but among African babies the decrease appeared to be associated with socioeconomic advantage. CONCLUSION: There has been a downward trend in birth weights in Portugal among both Portuguese and African term births, but average birth weights of the two groups were similar.     

Should gestational weight gain recommendations be tailored by maternal characteristics?

The authors tested whether the relation between gestational weight gain (GWG) and 5 adverse pregnancy outcomes (small-for-gestational-age (SGA) birth, large-for-gestational-age (LGA) birth, spontaneous preterm birth, indicated preterm birth, and unplanned cesarean delivery) differed according to maternal race/ethnicity, smoking, parity, age, and/or height. They also evaluated whether GWG guidelines should be modified for special populations by studying GWG and risk of at least 1 adverse outcome within different subgroups. Data came from a cohort of 23,362 normal-weight mothers who delivered singletons at Magee-Womens Hospital in Pittsburgh, Pennsylvania (2003-2008). Adequacy of GWG was defined as observed GWG divided by recommended GWG. The synergy analysis found that the combination of smoking, black race/ethnicity, primiparity, or short height with poor GWG was associated with an excess risk of SGA birth, while high GWG combined with each of these characteristics diminished risk of LGA birth in comparison with the same GWG among the women's counterparts. Nevertheless, there were no significant or meaningful differences in the risk of at least 1 adverse outcome between the GWG recommended by the Institute of Medicine in 2009 and the GWG that minimized risk of the composite outcome. These findings do not support the tailoring of GWG guidelines on the basis of a mother's smoking status, race/ethnicity, parity, age, or height among normal-weight women.     

Excessive maternal weight gain patterns in adolescents

The objective of this study was to examine the correlates of excessive maternal weight gain among adolescent mothers in the United States. Data from the Centers for Disease Control & Prevention 2000 natality file were analyzed to examine weight gain among adolescents (≤19 years) compared with their older counterparts (≥20 years). Using the Institute of Medicine guidelines, we defined excessive weight gain as more than 40 pounds. Our study population was restricted to singleton births, delivered after 36 weeks of gestation, who did not live in California. Maternal weight gain distributions were tabulated by maternal age and other maternal characteristics. Demographic characteristics potentially associated with maternal weight gain were compared for adolescents and older mothers. We further evaluated the role of parity and maternal race on the relationship between excessive weight gain and maternal age. Odds ratios and 95% confidence intervals were estimated using logistic regression. Over 27% of adolescent mothers gained excessive weight during pregnancy, although approximately 18% of their older counterparts gained more than 40 pounds. The association between young maternal age and weight gain was stronger for primiparous women than multiparous women and stronger among non-Hispanic white and non-Hispanic black mothers than Hispanic mothers. Adolescents were more likely to gain excessive weight than their older counterparts in nearly all demographic categories, regardless of parity or race. Adolescents are at high risk of gaining an excessive amount of weight during pregnancy and should be monitored during pregnancy by dietetics professionals.     

Maternal height as an independent risk factor for neonatal size among adolescent bengalees in kolkata, India

Background

Low Birth Weight is a major public health problem in developing countries. The causes of LBW are multifactorial including complication during pregnancy, genetic, environmental, social-cultural, demographic and nutritional variables. Comparison of anthropometric risk factors for neonatal size of adolescent mothers are lacking from West Bengal. Therefore, this study was undertaken to identify maternal anthropometric characteristics, which most strongly influence neonate weight and length among Bengalee mothers.

Methods

A hospital based cross-sectional study was undertaken during 2004 in a Government general hospital in South Kolkata, India. A total of 76 adolescent (age<20years) pregnant women were enrolled from obstetric ward who were admitted for delivery. Due to 4 perinatal deaths; a total of 72 adolescent mother- baby pairs were included in this analysis. Anthropometric measurements were undertaken immediately after delivery following stabilization as well maternal body mass index (BMI) was calculated using standard formula.

Results

The prevalence of low birth weight (LBW) in the present study was 52.8%. The results revealed that 30.6% of mothers were undernourished (BMI<19.8 kg/m²). It was noted that about 64% of undernourished mothers delivered LBW baby. Linear regression analyses of neonatal weight and length as dependent variables revealed that in both cases, maternal height had the most significant impact. It showed 12.9% (birth weight) and 16.1% (birth length) of variation. Moreover, the proportion of LBW was 75%, 52.3% and 25% among short (height ≤145 cm), average (146–155cm) and tall (>155cm) mothers (x²=6.855, p<0.01), respectively. Short mothers had 2.74 and 9.0 fold greater risk of delivering LBW baby than average and tall mothers. In contrast, mean birth weight and length of baby was lower in short mother than their counterparts.

Conclusion

This study revealed that maternal height had the strongest significant impact on neonate size. This strong association could have serious health implications for Bengalee adolescent mothers. However, since this is a preliminary finding, it needs validation using a larger sample of adolescent mothers.     

Rehospitalization of infants born to adolescent mothers

This study defines the variables that predict rehospitalization of infants born to teen mothers. Rehospitalization was defined as hospital admission during the first year of life subsequent to hospitalization at birth. Normal birth weight (NBW), but not low birth weight (LBW), infants of adolescent mothers had higher rehospitalization rates than infants of older mothers. NBW infants of young vs. older mothers had significantly higher rehospitalization rates for gastroenteritis. Among infants of adolescent mothers, the variables associated with increased risk of rehospitalization were unemployed household head, presence of a congenital anomaly or developmental delay, and an unusually high or low number of well child care visits. Although individual variables were significant at the bivariate level, in combination, these variables were poor predictors of which infants would be rehospitalized. Our study suggests that all teen mothers of NBW infants may require additional education to prevent excess rehospitalization of their infants.     

What does skin color have to do with infant health? An analysis of low birth weight among mainland and island Puerto Ricans

This study investigates the relationship between maternal skin tone and low birth weight among Puerto Ricans, a group with a complex ancestry and skin tones that range from very light to very dark. Using data from a representative sample of Puerto Rican mothers, we assess whether skin tone has different implications for low birth weight in three geographic areas (Puerto Rico; New York City; other eastern states). The analysis shows that skin tone is unrelated to low birth weight in Puerto Rico and New York City. However, in the other eastern states in our sample, mothers with dark skin have a high risk of bearing a low birth-weight infant, relative to mothers with light skin. We interpret our findings in light of differences in the social meaning of phenotypic differences across locales.     

Is paternal age associated with an increased risk of low birthweight,preterm delivery,and multiple birth?

OBJECTIVE: To determine if paternal age elevates the risk of low birthweight (< 2500g, LBW), preterm birth (< 37 weeks gestation), and multiple gestation among mothers whose age does not predict an elevated risk. DESIGN/METHODS: Population data on birth outcome, maternal age and paternal age was obtained from Alberta Health and Wellness for all births 1990-1996. RESULTS: Among women aged 25 to 29, regardless of parity, there was no linear relationship between paternal age and preterm birth or LBW. However, multiple birth rates increased with increased paternal age (p < 0.01). Among singleton births, advanced paternal age (>50 years) increased the risk of LBW and preterm birth (p < 0.05). CONCLUSIONS: Paternal age is not a risk factor for LBW or preterm delivery among low risk women. The increased risk of multiple birth with increased paternal age, regardless of parity, requires confirmation among other populations.     

Does maternal smoking during pregnancy have a direct effect on future offspring obesity? Evidence from a prospective birth cohort study

The authors used a population-based birth cohort of 3,253 children (52% males) born in Brisbane, Australia, between 1981 and 1984 to prospectively examine whether maternal smoking during pregnancy was associated with offspring overweight and obesity. The authors compared mean body mass indexes (weight (kg)/height (m)2) and levels of overweight and obesity at age 14 years among offspring by patterns of maternal smoking (never smoked, smoked before and/or after pregnancy but not during pregnancy, or smoked during pregnancy). Adolescent body mass index and prevalences of overweight and obesity were greater in offspring whose mothers had smoked during pregnancy than in those whose mothers had never smoked. Body mass index and levels of overweight and obesity among adolescent offspring whose mothers stopped smoking during pregnancy but smoked at other times in the child's life were similar to those among offspring whose mothers had never smoked. These results were independent of a range of potentially confounding factors and suggest a direct effect of maternal smoking during pregnancy on adolescent overweight and obesity. They provide yet another incentive for pregnant women to be persuaded not to smoke and for young women to be encouraged to never take up smoking.     

Anthropometric predictors of low birth weight outcome in teenage pregnancy

The highest relative risks of low birth weight are found among births to teenage mothers. An analysis of anthropometrics (weight, mid-arm circumference, and triceps skinfold) among black teenagers attending an adolescent prenatal program was studied. The sample consisted of 100 girls under 17 years. Data were collected from 19 to 35 weeks gestation. Adolescent mothers who delivered low birth weight (LBW) infants demonstrated different patterns of anthropometric changes than teen mothers who delivered normal birth weight (NBW) infants. Mean mid-arm circumference increases in the LBW group (0.05 mm/wk) were significantly less than mean increases in the NBW group (0.80 mm/wk) (p < 0.05). Arm fat area estimates of the LBW mothers demonstrated weekly depletion (−24.9 mm²/wk), which was significantly less than those of the NBW group, who accumulated fat (+ 15.3 mm²/wk) (p < 05). Changes in maternal nutritional status may in part mediate the birthweight outcome in adolescent pregnancy. Anthropometrics may be useful in predicting the teens at highest risk of bearing LBW infants.     

Maternal nutritional status and adolescent pregnancy outcome

To investigate the determinants of low birth weight of infants born to adolescent mothers, we studied the obstetric population attended at the Maternity Hospital of Lima, Peru. From this population we selected for study a sample of 1256 adolescent mothers ranging in age from 12 to 25 yr. The study included anthropometric and biochemical measurements used to evaluate nutritional status and physiological maturity of the mother and newborn. Findings from the present research indicate that the low birth weight of infants born to adolescent mothers is not due to premature delivery (short gestation) or low gynecological maturity. Furthermore, young adolescent mothers had smaller and thinner newborns than those born to older women who were adjusted for nutritional status during pregnancy and at delivery. That is, despite the similar nutritional status among the young adolescent mothers, the availability of nutrients for the accumulation of calories in the fetus (measured by skinfold thickness) was less than that of older women. Furthermore, the pregnancy weight gain associated with an optimal or average newborn weight is greater for young teenagers than for older women. These findings support the hypothesis that among rapidly growing teenagers the nutritional requirements of pregnancy may be greater than those of older women, and that this increased requirement competes with the growth needs of the fetus.     

#3 Parity,age at first birth,and risk of invasive cervical cancer: Meta-analyses

PURPOSE: The roles of parity and age at first birth as risk factors for cervical cancer remain unclear, although several studies in different populations have examined this question. We performed meta-analyses to predict relative risk of invasive cervical cancer as functions of parity and of age at first birth by fitting a variety of models.METHODS: We fit models relating the logarithm of relative risk for cervical cancer to parity and to age at first birth. Parity models were based on parity-specific relative risk estimates from 21 studies published between 1985 and 2001. Age at first birth models were based on corresponding data from 11 studies published during the same time period. Some models included covariates indicating whether individual studies adjusted for human papilloma virus (HPV) status, number of sex partners, age at first birth (parity models only), and/or parity (age at first birth models only).RESULTS: Relative risk for cervical cancer was found to increase with parity, at a declining rate (i.e., the greatest increase in risk was between parity 0–1, with consistently smaller increases thereafter). Relative risk for first birth at ages ⩾17 was significantly lower than relative risk for first birth at age 13, but no significant relationship was found between relative risk and age at first birth for first birth at ages ⩾17. Overall, indicators of whether studies adjusted for covariates were unable to explain the large variations among study results.CONCLUSION: Risk of invasive cervical cancer was associated with increasing parity, with the greatest increase in risk with the first birth. Risk was decreased for first birth at age 17 compared to 13; for first birth at ages ⩾17, we were unable to derive a quantitative relationship between age at first birth and relative risk for cervical cancer.     

Residual confounding explains the association between high parity and child mortality

Background

This study used data from recent Demographic and Health Surveys (DHS) to examine the impact of high parity on under-five and neonatal mortality. The analyses used various techniques to attempt eliminating selection issues, including stratification of analyses by mothers’ completed fertility.

Methods

We analyzed DHS datasets from 47 low- and middle-income countries. We only used data from women who were age 35 or older at the time of survey to have a measure of their completed fertility. We ran log-binominal regression by country to calculate relative risk between parity and both under-five and neonatal mortality, controlled for wealth quintile, maternal education, urban versus rural residence, maternal age at first birth, calendar year (to control for possible time trends), and birth interval. We then controlled for maternal background characteristics even further by using mothers’ completed fertility as a proxy measure.

Results

We found a statistically significant association between high parity and child mortality. However, this association is most likely not physiological, and can be largely attributed to the difference in background characteristics of mothers who complete reproduction with high fertility versus low fertility. Children of high completed fertility mothers have statistically significantly increased risk of death compared to children of low completed fertility mothers at every birth order, even after controlling for available confounders (i.e. among children of birth order 1, adjusted RR of under-five mortality 1.58, 95% CI: 1.42, 1.76). There appears to be residual confounders that put children of high completed fertility mothers at higher risk, regardless of birth order. When we examined the association between parity and under-five mortality among mothers with high completed fertility, it remained statistically significant, but negligible in magnitude (i.e. adjusted RR of under-five mortality 1.03, 95% CI: 1.02-1.05).

Conclusions

Our analyses strongly suggest that the observed increased risk of mortality associated with high parity births is not driven by a physiological link between parity and mortality. We found that at each birth order, children born to women who have high fertility at the end of their reproductive period are at significantly higher mortality risk than children of mothers who have low fertility, even after adjusting for available confounders. With each unit increase in birth order, a larger proportion of births at the population level belongs to mothers with these adverse characteristics correlated with high fertility. Hence it appears as if mortality rates go up with increasing parity, but not for physiological reasons.

     

A Comparison of Low Birth Weight Among Newborns of Early Adolescents,Late Adolescents,and Adult Mothers in the Peruvian Amazon

To compare low birth weight (LBW: <2,500 g) between infants born to adolescent and adult mothers in Iquitos, Peru. A random sample of 4,467 records of women who delivered at the Hospital Apoyo Iquitos between 2005 and 2007 was collected from hospital birth registries. Multivariate logistic and linear regression analyses were performed to compare LBW in newborns of adolescents (10–14, 15–19 years) and adults (≥20 years) and then for primiparous mothers with a normal gestational age, adjusting for newborn sex, antenatal care, and location of the mother’s residence. A total of 4,384 mothers had had a singleton live birth and 1,501 were primiparous with a normal gestational age. Early and late adolescents had significantly greater odds of having a LBW infant than adults (OR = 2.28, 95%CI: 1.09, 4.78; OR = 1.67, 95%CI: 1.30, 2.14, respectively). For primiparous mothers with a normal gestational age, the same was true only for early adolescents (OR = 3.07, 95%CI: 1.09, 8.61). There were significant differences in mean birth weight between adults (3178.7 g) and both adolescent age groups overall (10–14 years: 2848.9 g; 15–19 years: 2998.3 g) and for primiparous mothers with a normal gestational age (10–14 years: 2900.8 g; 15–19 years: 3059.2 g; ≥20 years: 3151.8 g). Results suggest there is an important difference between adolescent and adult mothers in terms of newborn birth weight, especially among early adolescents. Future research on LBW and possibly other adverse birth outcomes should consider early adolescents as a separate sub-group of higher risk.     

Social support and maternal depression from pregnancy to postpartum: the association with positive maternal behaviours among Brazilian adolescent mothers

Adolescent motherhood is a risky situation related to poorer quality of infant caregiving. The lack of social support and increased odds for maternal depression are the main concerns. This study aimed to investigate whether maternal–foetal attachment, social support and maternal depression measured during pregnancy and after birth were associated with postpartum maternal behaviours among Brazilian adolescent mothers. Forty-one adolescent mothers participated (M_age?=?16.88 years; SD?=?1.60) in the first two waves of a longitudinal study. Both mother and infant behaviours were assessed during videotaped home observations at three months postpartum. Hierarchical regression analysis indicated that positive postpartum maternal behaviours were strongly related to concurrent, rather than prenatal, measures of social support and maternal depression. Infant birth weight was also associated with positive maternal behaviours. Findings contribute to a better understanding of the personal and contextual factors affecting maternal behaviours shortly after birth in a high-risk sample of adolescent mothers.     

Risk factors for low birth weight in a socio-economically disadvantaged population: parity,marital status,ethnicity and cigarette smoking

Low birth weight (LBW) is a public health problem, because it is associated with increased risk of morbidity and mortality. The principal aim of this study was to assess risk factors for LBW in a large multi-ethnic and socio-economically disadvantaged population. Data from 3242 mothers, who attended the Well Baby Clinic (Southwestern Sydney, Australia) for the first time, were analysed in relation to their demographic characteristics and socio-economic indices. The overall birthweight was 3377 ± 577 g (mean ± SD). In multiple linear regression analysis, smoking during pregnancy, marital status, parity, and country of birth were independently associated with birth weight. According to this analysis, lower birth weight was associated with mothers who had smoked during pregnancy (by 215.2 ± 18.6 g), who were single (46.9 ± 21 g), and of Asian background (108.5 ± 38.2 g). However, higher parity was associated with significantly higher birth weight. The presence of each factor was coded as 1 and the absence, 0. A risk score was then derived by summing up the individual scores. When birth weight was classified as low birth weight (defined as those with birth weight being less than 2500 g) or normal birth weight, the overall prevalence of LBW was 1.9%. Each unit increase in the risk score was associated with a 1.9-fold (95% confidence interval: 1.5–2.6) increase in the risk of LBW. These data suggest that apart from marital status, ethnicity and parity, maternal smoking is the single most important preventable risk factors for LBW.     

Factors associated with birth weight in Sweden: the study of men born in 1913.

STUDY OBJECTIVE: To analyse factors associated with birth weight and to evaluate the validity of obstetrical data. DESIGN: Obstetrical data were retrieved for singleton men born in 1913 and living in Gothenburg, Sweden in 1963. Information on birth weight, maternal age, marital status, parity, social class, proteinuria, gestational age, and place of birth (home or hospital) was obtained from these birth records. SETTING: Sweden. PARTICIPANTS: Fifty year old men living in Gothenburg, Sweden, in 1963. MAIN RESULTS: Obstetrical records were obtained for 524 men (65%). Place of birth, gestational age, maternal age, parity, proteinuria, and marital status were all significantly correlated to birth weight. In multivariate analyses, place of birth, gestational age, parity, and proteinuria influenced birth weight. There was a substantial difference in mean birth weight between hospital deliveries (3352 g) and home deliveries (3817 g), which could be explained only partly by sociodemographic variables. Birth weight increased with parity and gestational age in home delivered babies as well as those delivered in a hospital. CONCLUSIONS: The validity of obstetrical records from 1913 was good. The place of birth (home or hospital) is strongly associated with birth weight and may be a confounding factor in studies of the implications of birth weight for future risk of disease or death.     

Neighborhood support and the birth weight of urban infants

Differences in maternal characteristics only partially explain the lower birth weights of infants of African-American women. It is hypothesized that economic and social features of urban neighborhoods may further account for these differences. The authors conducted a household survey of 8,782 adults residing in 343 Chicago, Illinois, neighborhoods to assess mean levels of perceived social support and used US Census data to estimate neighborhood economic disadvantage. Data on birth weight and maternal risk factors were gathered from 95,711 birth certificates (1994-1996). Before statistical adjustment of the data, infants born to African-American mothers were found to be, on average, 297 g lighter than those born to White mothers. After adjustment for individual-level risk factors, this difference was reduced to 154 g. For African-American mothers only, mean birth weight decreased significantly as the neighborhood level of economic disadvantage increased. For White mothers only, a significant positive association was found between perceived levels of neighborhood social support and infant birth weight. Adding these neighborhood-level predictors to the model reduced the adjusted White versus African-American difference in birth weight to 124 g. Results support the hypothesis that neighborhood-level factors are significantly associated with infant birth weight.     

Mothers and their pregnancies: a comparison of three population-based cohorts in Southern Brazil

Mothers from the 1982, 1993 and 2004 Pelotas birth cohorts were compared across biological, socioeconomic, demographic and reproductive characteristics. Women in the 2004 cohort had higher levels of education, gained more weight during pregnancy, and were heavier at the beginning and end of their pregnancy than mothers who gave birth in 1993 and 1982. There was an important increase in obesity rates (body mass index > 30kg/m(2)) over the 22 years of the study. Mean parity decreased from 1.3 in 1982 to 1.1 in 2004, with a growing proportion of primiparas and a decline in the proportion of women with > or = 4 children. The mean birth interval increased from 33.5 months in 1982 to 65.7 in 2004. Smoking during pregnancy decreased from 35.6% in 1982 to 25.1% in 2004. As with other characteristics, the change in smoking status differed according to income, with higher reductions among the wealthiest (from 24.9% to 8.7%) than among the poorest mothers (from 43.7% to 33.6%). In general terms, between 1993 and 2004 there was a decrease in the prevalence of maternal risk factors for unfavorable perinatal outcomes.