Preterm births, low birth weight, and intrauterine growth restriction in three birth cohorts in Southern Brazil: 1982, 1993 and 2004

Three birth cohort studies from 1982, 1993 and 2004, in Pelotas, Southern Brazil provided the data for this study of trends in preterm births, low birth weight, and intrauterine growth restriction. We found a slight increase in the period in the low birth weight prevalence from 9% to 10%. Intrauterine growth restriction decreased from 14.8% in 1982 to 9.4% in 1993, and subsequently increased to 12% in 2004, whereas preterm births increased markedly, from 6.3% in 1982 to 14.7% in 2004. This striking increment could not be explained by changes in maternal characteristics, as mothers in 2004 were heavier, smoked less during pregnancy and attended antenatal clinics more often and earlier than those of previous cohorts. However, pregnancy interruptions due either to caesarean sections or to inductions significantly increased. Caesareans increased from 28% in 1982 to 45% in 2004, and inductions were 2.5% in 1982 but 11.1% in 2004. The increase in preterms could be partially explained by the growing number of pregnancy interruptions, but there must be other causes since this increase was also observed among babies born by non-induced vaginal deliveries.     

The use of maternal and child health services in three population-based cohorts in Southern Brazil, 1982-2004

This study aimed to describe indicators of health care assistance during antenatal care, delivery and in the first year of life in Pelotas, Rio Grande do Sul State, Brazil. In 1982, 1993, and 2004, all hospital newborns from the urban area of Pelotas were enrolled in a cohort study. In this period, the number of pregnant women that did not attend antenatal care fell from 4.9% to 1.9%; the mean number of appointments increased from 6.7 to 8.1; and the number of women who began antenatal care in the third trimester of pregnancy decreased from 14.8% to 7%; caesarean sections increased from 27.7% to 45.2% and the proportion of deliveries assisted by physicians increased from 61.2% to 89.2%. Improvements in immunization rates during the first year of life mainly occurred between 1982 and 1993, while the number of preventive medical appointments improved among those born in 2004. This increase in coverage was greater for low-income mothers and children, which may reflect the implementation of universal coverage in Brazil; however, coverage levels in 1982 were already high for wealthy mothers and children, reducing the scope for further gains.     

The epidemiological transition in maternal and child health in a Brazilian city, 1982-93: a comparison of two population-based cohorts

Two studies carried out in 1982 and 1993 in the city of Pelotas, Southern Brazil, provide a unique opportunity for assessing the impact on maternal and child health of the economic and health care changes, which took place in Brazil in this period. The cohorts of mothers and infants of 1982 and 1993 were studied from the time of delivery. In both years, all mothers identified in the city's maternity hospitals answered a standardised questionnaire and their infants were examined. Over 99% of all children born in the city in each of the 2 years were included in the cohorts. Deaths occurring among these children were monitored prospectively, as well as all hospital admissions in the 1993 cohort. In the 1982 study, attempts were made to locate a 25% sample of the children at the mean age of 12 months using the addresses collected at the hospital (82% of the children were located), and all of the cohort children at the mean age of 20 months and 42 months, through a city census (87% were located in both follow-ups). In the 1993 study, 20% of all children plus all low birthweight infants were sought at 12 months of age, using the addresses collected at the hospital, and 95% were successfully traced. There was a 12% fall in the number of births occurring in 1993 (5,304 births), in comparison with 1982 (6,011 births), in spite of the increase in the population of reproductive age in the city during the decade. There was a marked difference in maternal height and weight at the beginning of pregnancy, with women giving birth in 1993 being, on average, 3.4 cm taller and 2.5 kg heavier than those who gave birth in 1982. The proportion of preterm babies (<37 weeks), measured by the date of last menstrual period, increased from 5.6% in 1982 to 7.5% in 1993. The median duration of breast feeding increased from 3.1 months in 1982 to 4.0 months in 1993. At 12 months of age, the prevalence of deficit of weight for age decreased from 5.4% in 1982 to 3.7% in 1993. The prevalence of deficit of height for age, however, increased from 5.3% to 6.1%. The perinatal mortality rate dropped 31%, from 32.2 per 1,000 births in 1982 to 22.1 deaths per 1,000 births in 1993. There was also a marked reduction in the infant mortality rate, from 36.4 per 1,000 livebirths in 1982 to 21.1 per 1,000 livebirths in 1993. The findings of the study indicate that there were improvements in the decade for most of the indicators evaluated, with the exception of birthweight and gestational age. It appears that improvements in perinatal and infant mortality rates are largely due to improvements in the health care sector.     

Perinatal mortality in three population-based cohorts from Southern Brazil: trends and differences

Trends in perinatal mortality were studied in the city of Pelotas, Southern Brazil, using three population-based cohort studies carried out in 1982, 1993 and 2004. The objective of the present study was to analyze trends and differences in perinatal mortality during the 1982-2004 period. All hospital deliveries and perinatal deaths were monitored through daily visits to maternity wards. Cause of death was determined using information from hospital records and by interviewing physicians. Perinatal mortality fell by 43% in the two decades, with a greater reduction between 1982 and 1993. Intrapartum fetal deaths decreased by 72% and deaths from asphyxia fell from 4.5 per thousand in 1982 to 1.4 per thousand in 2004. In conclusion, reductions in perinatal mortality were also seen across all birth weight categories between 1982 and 1993, but the same was not true for the 1993 to 2004 period, when mortality increased in several categories above 2,000g.     

Infant malnutrition and obesity in three population-based birth cohort studies in Southern Brazil: trends and differences

The aim of this study was to compare the evolution of nutritional deficits and overweight in one-year-old children from three birth cohorts started in 1982, 1993 and 2004 in Pelotas, Southern Brazil. Samples from the 1982 and 1993 cohorts and all children from 2004 were weighed and measured, and their mothers interviewed. Anthropometric deficits and overweight were assessed using both NCHS and WHO growth standards. A comparison of the existence of nutritional deficits showed that, after a decline between 1982 and 1993, its prevalence stabilized between 1993 and 2004. Across the whole period, a decrease in all deficits was observed. Obesity, on the other hand, increased. A deficit in the ratio of body length to age was found to be strongly associated with family income. The group with income below one minimum wage was the only to present a significant reduction of stunting during the study period. The most significant improvements in the reduction of nutritional deficits occurred in the first half of the study period, while social differentials remained. Fighting malnutrition is still necessary among the 40% of the population considered poor, and must be accompanied by efforts to combat overweight which is being observed in all social strata.     

Maternal exposure to Great Lakes sport-caught fish and dichlorodiphenyl dichloroethylene, but not polychlorinated biphenyls, is associated with reduced birth weight

Fish consumption may be beneficial for a developing human fetus, but fish may also contain contaminants that could be detrimental. Great Lakes sport-caught fish (GLSCF) are contaminated with polychlorinated biphenyls (PCBs) and dichlorodiphenyl dichloroethylene (DDE), but the effects of these contaminants on birth outcome are not clear. To distinguish potential contaminant effects, we examined (1) whether the decrease over time in contaminant levels in GLSCF is paralleled by an increase in birth weight of children of GLSCF-consuming mothers and (2) the relation between maternal serum concentrations of these contaminants and birth weight. Mothers (n=511) were interviewed from 1993 to 1995, and maternal serum was collected from 1994 to 1995 (n=143). Potential confounders considered were child gender, maternal age at delivery, maternal prepregnancy body mass index, maternal cigarette and alcohol use during pregnancy, maternal education level, maternal parity, and maternal breastfeeding. Children born during 1970-1977, 1978-1984, and 1985-1993 to mothers who ate more than 116 meals of GLSCF before pregnancy were, on average, 164 g lighter, 46 g heavier, and 134 g heavier, respectively, than children of mothers who ate no GLSCF before pregnancy (P trend=0.05). GLSCF-consuming mothers had higher serum PCB and DDE concentrations, but only increased DDE was associated with lower birth weight. The data suggest that fetal DDE exposure (as indicated by maternal serum DDE concentration) may decrease birth weight and that decreased birth weight effects associated with GLSCF consumption have decreased over time.     

Comparison between two cohorts of adolescent mothers in municipality of the Southeastern, Brazil

OBJECTIVE: To compare the prevalence of pregnancy among adolescents and analyze trends in some social and biological variables among two cohorts of adolescent mothers in Ribeir?o Preto, Brazil, during 1978/79 and 1994. METHODS: Two cohorts of adolescent mothers were interviewed shortly after delivery, comprising 943 women in the first survey (1978/79) and 499 in the second (1994). Both surveys covered more than 98% of births in all childbirth clinics. Only singleton livebirths from adolescent mothers living in the municipality were included in the analysis. The Chi-square test was used for statistical analysis, with a 0.05 significance level. RESULTS: The percentage of adolescent mothers increased from 14.1% in 1978/79 to 17.5% in 1994 (p<0.05), mainly due to an increase in deliveries in the 13-17 years age group. There was a reduction in the number of smokers and mothers with lower schooling. The number of prenatal care visits increased. There was also an increase in the proportion of single mothers, of those who were employed and got private delivery care. Low birth weight and preterm birth rates remained unchanged for all of them. Cesarean section and forceps delivery rates increased substantially. Mothers in the 13-17 years age group however showed twice as much premature and low birth weight children, a higher proportion of single mothers with lower schooling, and higher rate of forceps delivery. CONCLUSIONS: Some characteristics of the adolescent mothers in the 13-17 years age group were more unfavorable when compared to the 18-19 years age group. The characteristics of adolescent age groups need to be better understood and taken into account in the prenatal and delivery care planning.     

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.     

Immediate and early postnatal care for mothers and newborns in rural Bangladesh

The study evaluated the impact of essential newborn-care interventions at the household level in the Saving Newborn Lives project areas. Two household surveys were conducted following the 30-cluster sampling method using a structured questionnaire in 2002 (baseline) and 2004 (endline) respectively. In total, 3,325 mothers with children aged less than one year in baseline and 3,110 mothers in endline from 10 sub-districts were interviewed during each survey. The proportion of newborns dried and wrapped immediately after birth increased from 14% in 2002 to 55% in 2004; 76.2% of the newborns were put to the mother's breast within one hour of birth compared to 38.6% in baseline. Newborn check-up within 24 hours of delivery increased from 14.4% in 2002 to 27.3% in 2004. Postnatal check-up of mothers by trained providers within three days of delivery rose from 2.4% in 2002 to 27.3% in 2004. Knowledge of the mothers on at least two postnatal danger signs increased by 17.2%, i.e. from 47.1% in 2002 to 64.3% in 2004. Knowledge of mothers on at least three postnatal danger signs also showed an increase of 16%. Essential newborn-care practices, such as drying and wrapping the baby immediately after birth, initiation of breastmilk within one hour of birth, and early postnatal newborn check-up, improved in the intervention areas. Increased community awareness helped improve maternal and newborn-care practices at the household level. Lessons learnt from implementation revealed that door-to-door visits by community health workers, using community registers as job-aids, were effective in identifying pregnant women and following them through pregnancy to the postnatal periods.     

Exploring Maternal Patterns of Dietary Caffeine Consumption Before Conception and During Pregnancy

We describe patterns of dietary caffeine consumption before and after pregnancy recognition in a cohort of women who recently gave birth. This study included 8,347 mothers of non-malformed liveborn control infants who participated in the National Birth Defects Prevention Study during 1997–2007. Maternal self-reported consumption of beverages (caffeinated coffee, tea, and soda) and chocolate the year before pregnancy was used to estimate caffeine intake. The proportions of prepregnancy caffeine consumption stratified by maternal characteristics are reported. In addition, patterns of reported change in consumption before and after pregnancy were examined by maternal and pregnancy characteristics. Adjusted prevalence ratios were estimated to assess factors most associated with change in consumption. About 97 % of mothers reported any caffeine consumption (average intake of 129.9 mg/day the year before pregnancy) and soda was the primary source of caffeine. The proportion of mothers reporting dietary caffeine intake of more than 300 mg/day was significantly increased among those who smoked cigarettes or drank alcohol. Most mothers stopped or decreased their caffeinated beverage consumption during pregnancy. Young maternal age and unintended pregnancy were associated with increases in consumption during pregnancy. Dietary caffeine consumption during pregnancy is still common in the US. A high level of caffeine intake was associated with known risk factors for adverse reproductive outcomes. Future studies may improve the maternal caffeine exposure assessment by acquiring additional information regarding the timing and amount of change in caffeine consumption after pregnancy recognition.     

Pregnancy complications and delivery outcomes of pregnant women with common cold

OBJECTIVE: To study the association between common cold during pregnancy and pregnancy complications and delivery outcomes: gestational age/birth weight, in addition preterm birth and low birthweight. METHOD: In the population-based large data set of the Hungarian Case-Control Surveillance System of Congenital Abnormalities (HCCSCA), 1980-1996, controls without congenital abnormalities were analysed. RESULTS: Of 38,151 newborn infants, 5,475 (14.4%) had mothers with common cold. The prevalence of threatened preterm delivery, placental disorders and severe nausea and vomiting was lower while the occurrence of anemia was higher in pregnant mothers with common cold than in mothers without common cold. Mothers with common cold in pregnancy had 0.1 week shorter gestational age, thus the proportion of preterm births (9.8% vs 9.1%) was somewhat larger. However, mean birth weight was somewhat larger (3,305 vs 3,271 g) and the proportion of low birthweight newborns (4.2% vs 5.9%) was smaller. CONCLUSION: Common cold during pregnancy does not increase the occurrence of pregnancy complications except anemia, while delivery outcomes showed minor but opposite (higher rate of preterm birth and lower rate of low birthweight) changes.     

Grandmothers’ Smoking in Pregnancy and Grandchildren’s Birth Weight: Comparisons by Grandmother Birth Cohort

This study examined whether grandmothers’ smoking behavior during pregnancy was associated with birth weights in their grandchildren, considering possible birth cohort effects in the grandmothers’ generation. The birth weights of 935 singleton children were compared by grandmothers’ and mothers’ smoking status during pregnancy. In 2008, women (n = 397) from the Michigan Bone Health and Metabolism Study were interviewed about their own birth history, including whether their own mother smoked while pregnant with them, and the birth histories of their offspring. While also accounting for family clustering, linear mixed models were used to evaluate whether birth weight differences in the grandchildren were associated with grandmothers’ and mothers’ smoking behavior during pregnancy. Associations were compared among grandmothers born from 1904 to 1928 versus grandmothers born from 1929 to 1945 to determine potential birth cohort effects. Forty-six (5 %) grandchildren had grandmothers and mothers who smoked while pregnant, while 455 (49 %) had grandmothers and mothers who did not smoke during pregnancy. After adjustment, birth weight was an average of 346 (95 % confidence interval 64–628) grams higher in grandchildren whose grandmother and mother both smoked during pregnancy relative to grandchildren whose grandmother and mother both did not smoke during pregnancy, but only among grandmothers who were born from 1929 to 1945. For grandmothers born from 1904 to 1928, grandchildren birth weights did not differ by grandmother and mother smoking status. Birth weight may be associated with grandmother and mother smoking behaviors during pregnancy, but birth cohort effects should be considered.     

Mate drinking during pregnancy and risk of preterm and small for gestational age birth

Mate, a hot infusion of Ilex paraguayensis, is a beverage largely consumed in Southeast Latin America, including during pregnancy. To assess the effect of mate drinking during pregnancy on preterm and small for gestational age (SGA) birth, a cross-sectional study was done. From January 1st to December 31st, 1993, in the first 24 h after delivery, all 5304 mothers giving birth at the hospitals in Pelotas, Southern Brazil, were interviewed and several of their characteristics were gathered. Birthweight was recorded and gestational age at birth assessed using the Dubowitz score. All 5189 single births were analyzed. The prevalence of SGA and preterm birth was 8.0 and 9.1%, respectively. Mate intake at least once a week during the entire pregnancy period was reported by approximately 68% of the mothers. Crude analyses showed a 30% increase in the risk of SGA among daily mate drinkers compared with nonconsumers (prevalence ratio = 1.3; 95% CI 1.1-1.6), whereas no statistical association was detected with preterm births. After controlling for confounders, the significance of the association with SGA birth no longer held and the lack of association with prematurity remained unchanged. In conclusion, prevalence of daily mate drinking was high among pregnant women and, contrary to the hypothesis, no harmful effect on intrauterine growth or duration of pregnancy was detected.     

Birth Weight among Singletons Born to Foreign-Born Mothers in Taiwan: A Population-Based Birth Register Study

Background

We compared the birth weight of newborns born to foreign-born mothers (FBMs) and Taiwan-born mothers (TBMs), using data from the 2005–2006 Taiwan Birth Registry of singleton live births.

Methods

The Wilcox–Russell method, data restriction, and multiple linear regression were used to analyze the data. The rates of low birth weight (<2500 g) with 95% confidence intervals were computed for TBMs, and for each of the nationalities of FBMs.

Results

The mean birth weight of newborns of FBMs was 3157 g, which was higher than that of newborns of TBMs (3109 g). On analysis using the Wilcox–Russell method, both the rate and residual proportion of low-birth-weight (LBW) births were lower among newborns of FBMs (4.1% and 1.1%, respectively) than among newborns of TBMs (5.9% and 1.7%, respectively). After adjusting for sex, mode of delivery, maternal age, smoking status, predisposing maternal risk factors, and condition during pregnancy, the newborns of FBMs weighed 72.9 g (95% CI, 68.8 g to 77.0 g) more than the newborns of TBMs. When data were restricted to mothers without any adverse conditions and adjusted for maternal age, the differences in birth weight between the 2 groups remained unchanged. The rates of LBW deliveries among FBMs in Taiwan were significantly lower than those in their respective countries of origin.

Conclusions

In Taiwan, newborns of FBMs had a higher birth weight than those of TBMs, even after accounting for potential confounding factors, and had lower rates of LBW deliveries than did mothers in their respective countries of origin.Key words: birth weight, transnational marriage, foreign-born mothers     

Maternal hyperthermia during pregnancy and cardiovascular malformations in the offspring

During pregnancy, a number of factors predisposing to hyperthermia, such as sleeping in a water bed, sauna bathing, heatwave, high workplace temperature, and fever, are believed capable of harming the foetus. This study aimed to clarify possible associations of maternal workplace temperature, season of birth, sauna bathing, upper respiratory infection, and fever, with cardiovascular malformations in the offspring. The material was composed of all 573 cardiac malformations registered in Finland in 1982–84, and 1055 randomly chosen healthy controls. The mothers were interviewed at maternity welfare centers about three months after delivery. Fever (> 38°C) during early pregnancy was more prevalent among case mothers (10%) than controls (6%) (p< 0.01), largely manifest as increased risks of atrial septal defect and hypoplastic left heart. Upper respiratory infection was also more common among case mothers (26%) than controls (18%) (p < 0.001). By contrast, maternal workplace temperature, sauna bathing, and temperature of the environment (seasonal variation) were not associated with risk of cardiac malformation in the offspring. The use of acetylsalicylic acid-containing medication for reducing fever was equally common (7%) among case and control mothers.Corresponding author.     

Features of infant exposure to tobacco smoke in a cohort study in Tasmania.

STUDY OBJECTIVES: To document changes in smoking style around infants over time and to identify factors associated with the smoking hygiene of mothers and others. DESIGN: A population based cohort study. SETTING: Population based, involving 22% of live births in Tasmania, Australia. PARTICIPANTS: From 1 May 1988 to 30 April, 1993, 6109 infants and their mothers (89% of eligible infants) participated in the hospital and home interview of the cohort study. Infants eligible for cohort entry were those assessed at birth to be at a higher risk of SIDS. MAIN RESULTS: The overall proportion of mothers who smoked during pregnancy and postnatally did not decline. Increasing trends were found for mothers and others not smoking in the same room as baby or while holding or feeding the baby, significant over the five year period. Good smoking hygiene (mother not smoking in the same room as baby) was positively associated with--first birth (OR = 1.74 (1.30, 2.33)), low birth weight (1.69 (1.27, 2.23)), being born after 1 May 1991 (1.67 (1.33, 2.11)), and private health insurance status (1.39 (1.02, 1.90)). Good smoking hygiene was negatively associated with maternal smoking during pregnancy (0.50 (0.31, 0.80)), intention to bottle feed (0.62 (0.49, 0.78)), the level of maternal postnatal smoking, increasing numbers of smokers in the household, and parents cohabiting but unmarried. A similar analysis was conducted for other household residents who smoked. CONCLUSIONS: Changes in maternal smoking prevalence have been small. The exposure of infants to tobacco smoke postnatally has decreased significantly, although a large proportion of infants are still exposed to tobacco smoke. The identification of the above parental and infant factors associated with good smoking hygiene should be useful for health education planning.     

中国10县(市)1993-2005年单胎儿早产流行状况研究

目的描述中国10县（市）单胎儿早产流行状况及长期变化趋势。方法资料来源于“中美预防出生缺陷和残疾合作项目”中的围产保健监测数据库。研究对象为3省10县（市）在1993—2005年间所有孕满28周且分娩单胎儿（包括死胎死产）的孕产妇542923名，计算早产率并描述其分布特征。结果1993—2005年间在10县（市）共发生早产25784例（其中死胎死产1530例），早产率为4，75％（95％CI：4.69～4.81），活产儿早产率为4．49％（95％CI：4．44～4．55）。单胎早产率呈逐年下降趋势，无明显季节倾向；南方城市、南方农村和北方农村的早产率依次降低；分娩年龄与早产率呈“U”型关系；文化程度低、孕产次多、有早产史或自然流产史者早产率较高。结论10县（市）单胎早产率呈逐年下降趋势，不同地区差别显著。     

Infant mortality in three population-based cohorts in Southern Brazil: trends and differentials

We studied time trends in infant mortality and associated factors between three cohort studies carried out in Pelotas, Rio Grande do Sul State, Brazil, in 1982, 1993, and 2004. All hospital births and deaths were determined by means of regular visits to hospitals, registrar's offices, and cemeteries. This data was used to calculate neonatal, post-neonatal, and infant mortality rates per thousand live births. Rates were also calculated according to cause of death, sex, birth weight, gestational age, and family income. The infant mortality rate fell from 36.4 per 1,000 live births in 1982 to 21.1 in 1993 and 19.4 in 2004. Major causes of infant mortality in 2004 were perinatal causes and respiratory infections. Mortality among low birth weight children from poor families fell 16% between 1993 and 2004; however, this rate increased by more than 100% among high-income families due to the increase in the number of preterm deliveries in this group. The stabilization of infant mortality in the last decade is likely to be due to excess medical interventions relating to pregnancies and delivery care.