Determinants of size at birth in a Canadian population

Maternal Determinants of Birth Weight in Northern Ghana

OBJECTIVES

Weight at birth is usually considered as an indicator of the health status of a given society. As a result this study was designed to investigate the association between birth weight and maternal factors such as gestational weight gain, pre-pregnancy BMI and socio-economic status in Northern Ghana.

METHODS

The study was a facility-based cross-sectional survey conducted in two districts in the Northern region of Ghana. These districts were purposively sampled to represent a mix of urban, peri-urban and rural population. The current study included 419 mother-infant pairs who delivered at term (37-42 weeks). Mother's height, pre-pregnancy weight and weight changes were generated from the antenatal records. Questionnaires were administered to establish socio-economic and demographic information of respondents. Maternal factors associated with birth weight were examined using multiple and univariate regressions.

RESULTS

The mothers were generally well nourished before conception (Underweight 3.82%, Normal 57.76%, Overweight 25.06% and Obesity 13.37%) but approximately half of them could not gain adequate weight according to Institute of Medicine recommendations (Low weight gain 49.64%, Adequate weight gain 42.96% and Excessive weight gain 7.40%). Infants whose mothers had excess weight gain were 431g (95% CI 18-444) heavier compared to those whose mothers gained normal weight, while those whose mothers gained less were 479g (95% CI -682- (-276) lighter. Infants of mothers who were overweight and obese before conception were 246g (95% CI 87-405) and 595g (95% CI 375-815) respectively heavier than those of normal mothers, whereas those whose mothers were underweight were 305g (95% CI -565 -(-44) lighter. The mean birth weight observed was 2.98 ± 0.68 kg.

CONCLUSION

Our findings show that pre-pregnancy body mass index and weight gain during pregnancy influence birth weight. Therefore, emphasis should be placed on counseling and assisting pregnant women to stay within the recommended weight gain ranges.

Effects of an antenatal dietary intervention on maternal anthropometric measures in pregnant women with obesity

OBJECTIVE

The effect of providing antenatal dietary and lifestyle advice on secondary measures of maternal anthropometry was evaluated and their correlation with both gestational weight gain and infant birth weight was assessed.

METHODS

In a multicenter, randomized controlled trial, pregnant women with BMI of ≥25 kg/m(2) received either Lifestyle Advice or Standard Care. Maternal anthropometric outcomes included arm circumference, biceps, triceps, and subscapular skinfold thickness measurements (SFTM), percentage body fat (BF), gestational weight gain, and infant birth weight. The intention to treat principles were utilized by the analyses.

RESULTS

The measurements were obtained from 807 (74.7%) women in the Lifestyle Advice Group and 775 (72.3%) women in the Standard Care Group. There were no statistically significant differences identified between the treatment groups with regards to arm circumference, biceps, triceps, and subscapular SFTM, or percentage BF at 36-week gestation. Maternal anthropometric measurements were not significantly correlated with either gestational weight gain or infant birth weight.

CONCLUSIONS

Among pregnant women with a BMI of ≥25 kg/m(2) , maternal SFTM were not modified by an antenatal dietary and lifestyle intervention. Furthermore, maternal SFTM correlate poorly with both gestational weight gain and infant birth weight.

Parental smoking during pregnancy and ADHD in children: the Danish national birth cohort

BACKGROUND

Prenatal maternal smoking has been associated with attention-deficit/hyperactivity disorder (ADHD) in children, but the causal nature of this association is still under scrutiny. We examined the association with maternal smoking and nicotine replacement use during pregnancy, using association with paternal smoking as a marker of potential genetic or social confounding.

METHODS

We included 84 803 singletons who participated in the Danish National Birth Cohort. Information on parental smoking was reported by the mothers during pregnancy. Children with ADHD were identified from the Danish Psychiatric Central Register, the Danish National Patient Register, and the Register of Medicinal Product Statistics by the International Classification of Diseases, 10th Revision diagnosis or medication. We also used hyperactivity/inattention score of the parent-reported Strengths and Difficulties Questionnaire, included in the 7-year follow-up of the National Birth Cohort.

RESULTS

Maternal and paternal smoking during pregnancy were associated with an elevated risk of ADHD defined by hospital diagnosis, medication, and hyperactivity/inattention score, but the association was stronger for maternal smoking than for paternal smoking. Compared with children born to nonsmoking mothers and smoking fathers, children born of smoking mothers and nonsmoking fathers had a higher risk of ADHD (adjusted hazard ratio = 1.26; 95% confidence interval, 1.03 to 1.53). We also saw a higher risk of ADHD in children of mothers who used nicotine replacement during pregnancy.

CONCLUSIONS

Our findings indicate that the association between prenatal maternal smoking and ADHD may overestimate a causal link, but nicotine exposure or related factors may still play a causal role.

The evolution of human adiposity and obesity: where did it all go wrong?

Because obesity is associated with diverse chronic diseases, little attention has been directed to the multiple beneficial functions of adipose tissue. Adipose tissue not only provides energy for growth, reproduction and immune function, but also secretes and receives diverse signaling molecules that coordinate energy allocation between these functions in response to ecological conditions. Importantly, many relevant ecological cues act on growth and physique, with adiposity responding as a counterbalancing risk management strategy. The large number of individual alleles associated with adipose tissue illustrates its integration with diverse metabolic pathways. However, phenotypic variation in age, sex, ethnicity and social status is further associated with different strategies for storing and using energy. Adiposity therefore represents a key means of phenotypic flexibility within and across generations, enabling a coherent life-history strategy in the face of ecological stochasticity. The sensitivity of numerous metabolic pathways to ecological cues makes our species vulnerable to manipulative globalized economic forces. The aim of this article is to understand how human adipose tissue biology interacts with modern environmental pressures to generate excess weight gain and obesity. The disease component of obesity might lie not in adipose tissue itself, but in its perturbation by our modern industrialized niche. Efforts to combat obesity could be more effective if they prioritized 'external' environmental change rather than attempting to manipulate 'internal' biology through pharmaceutical or behavioral means.

Prenatal cigarette smoke exposure and postnatal respiratory responses to hypoxia and hypercapnia

Prenatal cigarette smoke (CS) exposure, in combination with hypoxia and/or hyperthermia can lead to gasping and attenuated recovery from hypoxia in 7 days old rat pups. We studied 95 unanesthetized spontaneously breathing 14 days old rat pups to investigate if the destabilizing effects of increased ambient temperature and prenatal CS exposure on respiratory control observed in 7 days old rats were still evident at day 14. This postnatal age was selected as it is beyond the analogous risk period for SIDS in human. Furthermore, we investigated if the breathing responses to hypercapnia are affected by prenatal CS exposure. Since high ambient (HA) temperature can lead to gasping and aberrant respiratory control, we recorded respiratory patterns at low (24-25°C) and high (29-30°C) ambient temperatures, and under hypoxic or hypercapnic states. No gasping was observed in 14 days old rat pups. During hypoxia, breathing frequency increased in the CS-exposed group under low and HA temperatures. Rectal temperature decreased only in the sham group in response to low ambient temperature hypoxia. At HA temperature, breathing frequency increased in both sham and CS-exposed groups during hypercapnia, however, it remained elevated during washout period only in the sham group. We demonstrate that prenatal CS exposure continues to have profound effects on respiratory and thermoregulatory responses to hypoxia and hypercapnia at day 14. The attenuated respiratory and thermoregulatory responses to acute hypoxia and hypercapnia on day 14 demonstrate a strong interaction between CS exposure, respiratory control, and thermoregulation during postnatal maturation.

Reproduction, aging, and body shape by three-dimensional photonic scanning in Thai men and women

OBJECTIVES

Aging and reproduction have been independently associated with body shape in women, with redistribution of body fat from lower to upper body regions. This may be interpreted as a life history strategy for allocating energy between competing peripheral fat depots for reproduction, and central fat depots for maintenance and survival. It remains unclear whether men show similar life history strategy in shape. The objectives of this study were to investigate associations between shape, age, and number of offspring in both men and women from Thailand.

METHODS

We analyzed data on body shape from three-dimensional photonic scanning, and number of reported offspring, available for 5,889 men and 6,449 women aged 16-90 years from the Thai National Sizing Survey.

RESULTS

Bearing children was associated with increased upper body girths and decreased lower body girths in women, independent of age, weight and height. Unlike motherhood, fatherhood was not associated with shape outcomes indexing adiposity, but was associated with arm girth, which may represent an index of sexual attractiveness. In those without children, aging was associated with greater upper body girths and reduced lower body girths, in both sexes.

CONCLUSIONS

Life history strategy in body shape is apparent in both sexes, with aging associated with a shift of tissue away from the lower limb to the upper body. Such strategy may reflect age-changes in the relative costs and benefits of different regional tissue masses. Changes in fat distribution related to aging and reproduction may contribute to the life-course development of cardiovascular risk.

Small for gestational age and higher birth weight predict childhood obesity in preterm infants

We sought to determine the association between small for gestational age (SGA), birth weight, and childhood obesity within preterm polysubstance exposed children. We sampled 312 preterm children with 11-year body mass index (BMI; age- and sex-specific) data from the Maternal Lifestyle Study (51% girls, 21.5% SGA, 46% prenatal cocaine, and 55% tobacco exposed). Multinomial regression analyzed the association between 11-year obesity (OBE) and overweight (OW) and SGA, birth weight, first-year growth velocity, diet, and physical activity variables. Overall, 24% were OBE (BMI for age ≥95th percentile) and 16.7% were OW (BMI ≥85th and <95th percentiles). In adjusted analyses, SGA was associated with OW (odds ratio [OR] = 3.4, confidence interval [CI] 1.5 to 7.5). Higher birth weight was associated with OBE (OR = 1.8, CI 1.3 to 2.4) and OW (OR = 1.4, CI 1.1 to 2.0). Growth velocity was associated with OBE (OR = 2.7, CI 1.8 to 4.0) and OW (OR = 1.6, CI 1.1 to 2.4). Low exercise was associated with OBE (OR = 2.1, CI 1.0 to 4.4) and OW (OR = 2.1, CI 1.0 to 4.5). There was no effect of substance exposure on obesity outcomes. Many (41%) of these high-risk preterm 11-year-olds were obese/overweight. Multiple growth-related processes may be involved in obesity risk for preterm children, including fetal programming as indicated by the SGA effect.

Gender, smoking during pregnancy and gestational age influence cord leptin concentrations in newborn infants

BACKGROUND

Low birth weight (BW), small head circumference, reduced length, increased preterm births and neuro-endocrine dysfunctions are among known consequences of smoking during pregnancy. Few studies have linked leptin to clinical features of growth restriction associated with maternal smoking and explored interaction with other determinants of size at birth, such as gender.

METHODS

Cord serum leptin concentrations were measured in 1215 term infants born to Caucasian mothers at completion of uneventful pregnancy. Serum concentrations were related to BW, gestational length, gender and maternal smoking and interaction with other determinants of size at birth evaluated.

RESULTS

Smoking was more frequent in younger (P<0.001) and shorter mothers (P=0.03) from lower socio-economic groups (SEGPs) (P<0.001). Infants born to smokers were lighter (190 g less), shorter and with smaller head circumference. Cord serum leptin concentrations were higher in girls (9.8 s.d. 7.6 ng/ml) than in boys (7.05 s.d. 5.8 ng/ml) (P<0.001). Boys were heavier (BW 3.52 s.d. 0.49 kg) than girls (3.39 s.d. 0.44 kg) (P<0.001), but girls had greater skinfold thickness measurements (sub-scapular and quadriceps skinfold thicknesses 5.5 s.d. 1.6 mm and 7.6 s.d. 1.9 mm respectively; boys 5.3 s.d. 1.6 vs 7.24+/-1.90 mm, P<0.001 respectively). Multivariate analyses showed gender (P<0.001), BW SDS (P<0.001), gestational length (P<0.001) and maternal smoking (P<0.042) as factors that influenced umbilical cord serum leptin concentrations in newborns.

CONCLUSION

Maternal smoking restrains foetal growth through placental vascular effects, and likely also via associated effects on leptin metabolism. More studies are needed to determine the influence that maternal smoking may have on placental syncytiotrophoblast and foetal adipose tissue.

Small for gestational age: short stature and beyond

Depending on the definitions used, up to 10% of all live-born neonates are small for gestational age (SGA). Although the vast majority of these children show catch-up growth by 2 yr of age, one in 10 does not. It is increasingly recognized that those who are born SGA are at risk of developing metabolic disease later in life. Reduced fetal growth has been shown to be associated with an increased risk of insulin resistance, obesity, cardiovascular disease, and type 2 diabetes mellitus. The majority of pathology is seen in adults who show spontaneous catch-up growth as children. There is evidence to suggest that some of the metabolic consequences of intrauterine growth retardation in children born SGA can be mitigated by ensuring early appropriate catch-up growth, while avoiding excessive weight gain. Implicitly, this argument questions current infant formula feeding practices. The risk is less clear for individuals who do not show catch-up growth and who are treated with GH for short stature. Recent data, however, suggest that long-term treatment with GH does not increase the risk of type 2 diabetes mellitus and the metabolic syndrome in young adults born SGA.

Reduced nephron number and glomerulomegaly in Australian Aborigines: A group at high risk for renal disease and hypertension

Aborigines in remote areas of Australia have much higher rates of renal disease, as well as hypertension and cardiovascular disease, than non-Aboriginal Australians. We compared kidney findings in Aboriginal and non-Aboriginal people in one remote region. Glomerular number and mean glomerular volume were estimated with the disector/fractionator combination in the right kidney of 19 Aborigines and 24 non-Aboriginal people undergoing forensic autopsy for sudden or unexpected death in the Top End of the Northern Territory. Aborigines had 30% fewer glomeruli than non-Aborigines--202,000 fewer glomeruli per kidney, or an estimated 404,000 fewer per person (P=0.036). Their mean glomerular volume was 27% larger (P=0.016). Glomerular number was significantly correlated with adult height, inferring a relationship with birthweight, which, on average, is much lower in Aboriginal than non-Aboriginal people. Aboriginal people with a history of hypertension had 30% fewer glomeruli than those without--250,000 fewer per kidney (P=0.03), or 500,000 fewer per person, and their mean glomerular volume was about 25% larger. The lower nephron number in Aboriginal people is compatible with their susceptibility to renal failure. The additional nephron deficit associated with hypertension is compatible with other reports. Lower nephron numbers are probably due in part to reduced nephron endowment, which is related to a suboptimal intrauterine environment. Compensatory glomerular hypertrophy in people with fewer nephrons, while minimizing loss of total filtering surface area, might be exacerbating nephron loss. Optimization of fetal growth should ultimately reduce the florid epidemic of renal disease, hypertension, and cardiovascular disease.

Normal and abnormal fetal growth

The fetal origins of adult disease hypothesis suggests that poor intrauterine growth is associated with an increased risk of cardiovascular disease. The hypothesis goes on to implicate different growth 'phenotypes', particularly disproportionate growth, in the determination of the type of cardiovascular disease that develops. Analysis of the antenatal growth of a low-risk pregnancy population does not identify such growth phenotypes within the general population. Rather, intrauterine growth is characterized by poor predictability of subsequent size, suggesting that centile crossing is a common feature of intrauterine growth. Furthermore, there is a sexually dimorphic pattern to this growth that needs to be considered in further work to test the fetal origins hypothesis.

Fetal growth velocities in Hong Kong Chinese infants

Few studies have investigated the velocities of fetal growth. The aim of the present study was to determine the pattern of 'fetal' growth velocities in a Chinese population. The gestation-specific measurements of the body weight, body length and head circumference in a representative sample of 5,045 male and 4,484 female newborns delivered between 26 and 42 weeks of gestation at 12 hospitals in Hong Kong were obtained. Peak growth velocity occurred before 30 weeks of gestation for head circumference, at week 30 for length and at week 30 for weight. When compared with data obtained from a French population, a significant difference in the growth velocity for body weight was observed below 32 weeks between French and Chinese infants, suggesting an ethnic difference in fetal growth of this parameter.

Housing conditions, perceived stress, smoking, and alcohol: determinants of fetal growth in Northwest Russia

BACKGROUND

Social determinants of health have become important in countries of the former Soviet Union during the time of transition.

AIM

This article estimates the influence of living conditions, smoking, alcohol, and maternal stress on fetal growth indices in an urban Russian setting.

METHODS

All pregnant women registered at antenatal care centres in Severodvinsk (Northwest Russia) and their infants comprised the study base (n = 1399). Multivariate linear regression analysis was applied to quantify the effects of the studied factors on birth weight and the ponderal index (PI) adjusted for maternal education, age, occupation, marital status, parity, pre-pregnancy weight, paternal employment, gestational age, and others.

RESULTS

Infants of smoking mothers were 126 g lighter compared with non-smokers [95% confidence interval (CI): -198; -54]. On average, birth weight decreased 27 g per cigarette smoked during pregnancy. Living in shared apartments, living in crowded housing situations, and perceived stress were associated significantly with birth weight loss: -89 g (95% CI: -153; -25), -82 g (95% CI: -136; -28), and -61 g (95% CI: -116; -7), respectively. A positive association between maternal alcohol consumption and birth weight was found. Living with parents was associated positively with both birthweight and PI. Infants whose fathers consumed more than 100 ml of absolute alcohol per week were thinner at birth compared with those of non-drinking and moderate drinking fathers.

CONCLUSIONS

Poor housing conditions, maternal stress, smoking, and alcohol consumption are independent determinants of fetal growth in Northwest Russia.

Adverse health effects of prenatal and postnatal tobacco smoke exposure on children

Parents who choose to smoke are possibly not aware of, or deny, the negative effects of passive smoking on their offspring. This review summarises a wide range of effects of passive smoking on mortality and morbidity in children. It offers paediatricians, obstetricians, specialists in preventive child health care, general practitioners, and midwives an approach to promote smoking cessation in smoking parents before, during, and after pregnancy.

The contribution of maternal smoking to preterm birth, small for gestational age and low birthweight among Aboriginal and non-Aboriginal births in South Australia

OBJECTIVES

To determine the contribution of maternal smoking to preterm birth (< 37 weeks' gestation), small for gestational age (SGA, birthweight < 10th percentile for gestational age) and low birthweight (< 2500 g) among Aboriginal and non-Aboriginal births in South Australia.

DESIGN

Retrospective cohort analysis of population-based perinatal data.

SETTING

The State of South Australia, population 1.5 million.

PARTICIPANTS

36059 women (of whom 851 were Aboriginal women) who had singleton births in 1998-1999.

MAIN OUTCOME MEASURES

Relative risks and population-attributable risks of preterm birth, SGA and low birthweight from smoking in the second half of pregnancy, by age and Aboriginality.

RESULTS

Aboriginal women had a higher rate of smoking in pregnancy than non-Aboriginal women (57.8% v 24.0% at the first antenatal visit) and high rates for all age groups, while the rates decreased with age among non-Aboriginal women. Heavy smoking increased with age, and Aboriginal women were heavier smokers. Women who smoked had elevated relative risks of preterm birth (1.64), SGA (2.28) and low birthweight (2.52), and all these showed a dose-response relationship. Among Aboriginal (versus non-Aboriginal) births, population-attributable risks were significantly higher for SGA (48% v 21%, and 59% for births to Aboriginal teenagers), low birthweight (35% v 23%) and preterm birth (20% v 11%).

CONCLUSIONS

Health promotion programs, with a focus on smoking cessation and reducing uptake of smoking, need to be implemented in an appropriate cultural context, especially among young Aboriginal women. Such a program is being developed in South Australia.

Weight concerns in women smokers during pregnancy and postpartum

When women smokers become pregnant, they are asked to control weight gain and at the same time to relinquish an addictive drug with weight suppressing effects. For women with serious body image concerns or a history of unhealthful eating patterns, smoking cessation may be particularly problematic. To investigate the relationship of weight concerns with smoking and weight gain during pregnancy and postpartum weight loss strategies, we conducted a retrospective study of women who had given birth to their first child within the past 10 years and were smokers when they became pregnant. We observed that women smokers with high weight and body image concerns (HC) gained significantly more weight during pregnancy-in amounts that far exceeded maximum recommended weight gain-than did women with low concerns (LC). HC were more likely to adopt smoking as a weight-control strategy and to be receptive to multiple weight-control strategies. Although they lost significantly more weight in the first month postpartum than did LC, they had also gained significantly more during pregnancy; the net result was that weight loss as a percentage of weight gained did not differ significantly between groups. HC were significantly less likely to experience food cravings in the first trimester and marginally less likely to vomit than LC. We conclude that early identification of high-risk women, coordination of prenatal care with smoking cessation counseling, and development of effective relapse prevention strategies that specifically address weight issues both during and after pregnancy will be needed if efforts to reduce smoking during pregnancy and postpartum are to be optimized.

Origins of fetal growth restriction

Regulation of growth of the fetus and its placenta begins before pregnancy. Early in pregnancy the mother sets the rate of growth of the fetus on a trajectory, which may be modified by events later in pregnancy. Low maternal weight for height, history of previous small babies, maternal undernutrition, pregnancy disorders, e.g. pre-eclampsia, are associated with low birthweight. Maternal smoking is a major factor in developed countries; infections and undernutrition in developing countries.Recently, there has been emphasis on adverse long-term outcomes including ischaemic heart disease, hypertension and diabetes associated with poor fetal growth. Experimental studies in animals show that some of these outcomes can readily be induced by restriction of fetal growth. Progress in determining successful treatments to improve the growth of the fetus has lagged behind these epidemiological and experimental findings. However, nutrient supplements improve growth in undernourished women and smoking cessation also improves fetal size and outcome.

Do big females have big pelves?

Previous studies have shown that maternal stature is a correlate of both pelvic size and reproductive efficiency. This study addresses the issue of body size and obstetric advantage. The relationship between pelvic size and three nonpelvic measures of body size is determined for females and males. The skeletal sample consists of blacks, whites, and Native Americans. The variables include 28 measures of the pelvis, length and head diameter of the femur, and clavicular length. The coefficient of multiple determination (CMD) is computed for each pelvic measure using multiple regression, with the three nonpelvic measures serving as the independent variables. Partial correlation coefficients are also calculated between each pelvic and nonpelvic variable, while controlling for the other two nonpelvic variables. The results show that all CMDs in females and all but one CMD in males are "low," i.e., below 33%. The sexes are nonsignificantly different in their CMDs for 22 of the 28 pelvic variables; of the six variables that are significantly different, five are of the midplane. The sexes are also broadly comparable in their partial correlations. The results are explained as follows. First, the concordance between the sexes in the relationship between pelvic size and nonpelvic measures of body size is due to their genetic similarity for homologous structures. Second, as pelvic size is at the minimum at the midplane, the sexual differences in CMDs are the result of selection with respect to obstetrics. Third, four explanations for the low CMDs are discussed: 1) lack of populationally or racially specific analysis; 2) nonlinear relationship between pelvic size and nonpelvic measures of body size; 3) combination of negative allometric selection between newborn body weight and maternal stature and weight with positive selection for maternal pelvic size; and 4) hormonally induced increase in pelvic capacity during parturition.

Racial patterns in the effects of tobacco use on fetal growth

OBJECTIVE

The aim of this study was to characterize the interaction between the effects on fetal growth of maternal smoking and race by means of race-specific growth normograms.

STUDY DESIGN

A case-control study was performed on white and African American mothers who were delivered at 2 hospitals in metropolitan Atlanta between February 1993 and December 1994. The study population consisted of 621 small for gestational age infants and their mothers and 324 appropriate for gestational age infants and their mothers. Face-to-face interviews with mothers and detailed anthropometric measurements of neonates were performed. Relationships among tobacco use, race, and fetal growth were evaluated by means of multiple logistic regression. The chi(2) test of trend was performed to assess a dose-response relationship between smoking and fetal growth.

RESULTS

Mothers of small for gestational age neonates were significantly more likely than control mothers to be single (52% versus 40%), to be primiparous (47% versus 37%), to have a low body mass index (26% versus 17%), to have hypertension (22% versus 15%), and to use alcohol (15% versus 9%). Mothers of small for gestational age infants were significantly more likely than control mothers to smoke (26% versus 12%) and to smoke more cigarettes (P <.05). After controlling for potential confounders cigarette smoking in the second trimester was significantly associated with small for gestational age infants in both races (whites <1 pack/d adjusted odds ratio 3.82, 1-2 packs/d adjusted odds ratio 4.86, >2 packs/d crude odds ratio; African Americans <1 pack/d adjusted odds ratio 2. 35, 1-2 packs/d adjusted odds ratio 2.52). The chi(2) test of trend results were consistent with a dose-response relationship between smoking and small for gestational age infants (whites chi(2) = 14.06, P <.0001, African Americans chi(2) = 7.99). Comparison between the 2 races of the adverse effects of smoking on fetal growth showed no significant difference.

CONCLUSION

Self-reported maternal smoking during the second trimester is associated with fetal growth restriction in a dose-response manner. According to race-specific growth normograms no significant difference in the effects of tobacco use on fetal growth was found between white and African American women.

The Washington State Intergenerational Study of Birth Outcomes: methodology and some comparisons of maternal birthweight and infant birthweight and gestation in four ethnic groups

A statewide database of vital records and hospital discharge summaries of obstetric and neonatal admissions for Washington State in 1987-95 was linked to the birth certificates of mothers born in the state. A total of 46,000 births to mothers of four racial/ethnic groups were studied: Whites, African-Americans, Native Americans and Hispanics. For all four groups inverse associations were found between maternal birthweight and infant low birthweight and preterm birth. The birthweight distribution of African-American mothers was displaced markedly downwards compared with the Whites; this difference in maternal birthweight is offered as a partial explanation of the greater prevalence of suboptimal pregnancy outcomes in the former. In contrast, the maternal birthweight distributions of Whites, Native Americans and Hispanics are similar; differences in pregnancy outcomes are probably more related to maternal preconceptional and postnatal factors in these groups as well as differences in pregnancy-related factors. Mothers' birthweight may have clinical value in identifying high-risk pregnancies.

Maternal body fat and water during pregnancy: do they raise infant birth weight?

OBJECTIVE

Our purpose was to determine the relation to infant birth weight of maternal fat and lean tissue during early and late pregnancy.

DESIGN

Total and net maternal pregnancy weight, fat, and water were determined from measurements of total body water, body density, and bone mineral mass in 200 women, with the use of a multicompartment model for body fat estimation in early and late pregnancy. Regression modeling was used to determine the relation of maternal body composition to birth weight, with control for maternal age, height, parity, and race and for infant gestational age and sex.

RESULTS

Maternal weight and body water at term were significantly associated with infant birth weight, but maternal body fat at term was not. These relations remained when maternal net values were used for weight, fat, and water to eliminate the contribution of the conceptus to these components.

CONCLUSION

In well-nourished women delivering at term, maternal body fat near term does not contribute significantly to infant birth weight, but maternal body water does.

Maternal menstrual history and small-for-gestational-age births in a population-based Chinese birth cohort

The relationship between maternal menstrual history and small-for-gestational-age (SGA) births is examined in a population-based birth cohort of 5291 mothers with singleton births and 28 completed gestational weeks in Qingdao, China, in 1992. Multivariate analyses suggest that the length of the menstrual cycle and age at menarche had independent effects on SGA after controlling for sex of the infant, physical size of the mother, blood pressure at the first antenatal visit, parity, gestational week at the first antenatal visit, number of antenatal visits, number of previous spontaneous abortions and maternal educational attainment and occupation. The relative risk (RR) of SGA among thin mothers (BMI < = 21) is 1.63 (95% confidence interval (CI) 1.16-2.29) if the mother's menarche started after 14 years (reference to < = 14 years), 1.75 (95% CI 0.96-3.20) if the mother's menstrual cycle was 29-30 days and 2.92 (95% CI 1.42-6.03) if the menstrual cycle > = 31 days ( < = 28 as a reference category for both). Among normal weight mothers (BMI 21-24), only a menstrual cycle equal or longer than 31 days still had a significant effect on SGA (RR 2.17, 95% CI 1.18-4.08), and among fat mothers no significant effects were observed. The results encourage further evaluation of the association between maternal menstrual background and fetal development among other ethnic populations and exploration of the possible biological mechanisms behind this relationship.

New South Wales population-based birthweight percentile charts

OBJECTIVE

To derive newborn percentile charts using NSW population and hospital-based data.

METHODOLOGY

Birthweight data for liveborn singleton infants were obtained from the New South Wales Midwives Data Collection (MDC) from 1990 to 1994 inclusive (n = 422139). Data were also collected from King George V Hospital (KGV) for liveborn singleton infants less than 35 weeks of gestation for 1982-89 inclusive, and for all gestations for 1990-95 inclusive (n = 30610). Birthweight percentiles were derived using the MDC data separately for males and females. Head circumference (n = 29090) and birth length percentiles (n = 26973) were derived from the KGV data.

RESULTS

The charts derived from MDC data had generally higher percentiles than previously published charts. These represent the largest Australian population-based study published to date.

CONCLUSIONS

Periodic review of newborn growth charts is recommended because of changing ethnic and socio-economic factors.

The effect of social deprivation on birthweight, excluding physiological and pathological effects

OBJECTIVE

To study the effect of social deprivation on birthweight, excluding the effect of known physiological factors and exploring the effect of possible pathological factors.

DESIGN

Retrospective analysis of computerised obstetric database.

SETTING

Two teaching hospitals and an associated district general hospital which provided a defined catchment area in the East Midlands.

SUBJECTS

The final analysis included 7493 women with complete datasets and gestations of between 259 and 300 days at delivery, dated by ultrasound scan.

MAIN OUTCOME MEASURES

Smoking habit, alcohol consumption, weight gain during pregnancy, systolic and diastolic blood pressures at booking, bleeding during pregnancy and Jarman score; also, the effect of these variables on birthweight, adjusted for the effects of physiological factors using the individualised birthweight ratio.

RESULTS

Smoking during pregnancy reduced birthweight but the effect is not linear, becoming less marked as the number of cigarettes smoked increases. Alcohol intake, diastolic and systolic blood pressures at the booking visit and vaginal bleeding during early pregnancy were not significantly related to birthweight. Pregnancy weight gain was significantly positively related to birthweight especially in the normal weight range (60-99 kg). A multivariate analysis including physiological and pathological factors found increasing Jarman score to be negatively related to birthweight.

CONCLUSIONS

In this central British population social deprivation is correlated negatively with birthweight: the most socially deprived mothers have the smallest babies. This association cannot be explained in terms of physiological differences in the population nor in a higher prevalence of known pathological factors.

The relationship between maternal skinfold thickness, smoking and birthweight in black and white women

A prospective study was conducted in a sample of 1491 multiparous women to ascertain whether the relationship between maternal tricep skinfold thickness and infant birthweight is modified by smoking status and whether the relationship is different in white and black infants. Maternal tricep skinfold thickness measured at midpregnancy was a significant predictor of infant birthweight in both white and black infants after adjusting for gestational age at birth, maternal height, maternal age, parity, alcohol consumption and sex of the infant. However, maternal tricep skinfold thickness was a better predictor of birthweight in smokers compared with nonsmokers. Both white and black women with tricep skinfold thickness below the sample mean had lower infant birthweight than women with tricep skinfold at or above the mean, after adjusting for gestational age at birth, but the difference was greater in smokers (198 g for white and 221 g for black infants) than in nonsmokers (124 g for white and 221 g for black infants) than in nonsmokers maternal subcutaneous fat measured by tricep skinfold thickness has a greater effect on infant birthweight in smokers compared with nonsmokers, with similar effects in white and black infants.

Vaginal bleeding and adverse reproductive outcomes: a meta-analysis

The objective of this paper is to characterise and quantify the association between vaginal bleeding and pregnancy outcome. A meta-analysis was performed in order to quantify the risk of adverse reproductive outcome by combining evidence from all previous studies of vaginal bleeding. The reproductive endpoints considered were low birthweight, preterm birth, stillbirth, perinatal death and congenital malformation. The meta-analysis confirms an association of vaginal bleeding with adverse pregnancy outcomes, but identified discrepancies in the reported risks of vaginal bleeding and magnitudes of association between bleeding and adverse reproductive outcomes, observed across studies. These discrepancies may be attributed to inconsistent definitions of the timing and severity of vaginal bleeding. The implications of such inconsistencies are discussed, suggesting a need for more standardised definitions of vaginal bleeding and reproductive endpoints in future studies.

Maternal risk factors and their influence on fetal anthropometric measurements

OBJECTIVE

Our purpose was to determine if and when maternal risk factors and fetal sex have an impact on specific fetal anthropometric measurements assessed by ultrasonography.

STUDY DESIGN

Serial ultrasonographic examinations were performed on 1205 fetuses of indigent multiparous women who ultimately gave birth at term. Femur length, abdominal circumference, and head circumference measurements were obtained at mean gestational ages of 18, 25, 31, and 36 weeks, and an estimated fetal weight was calculated. At birth the infant was weighted and head circumference, abdominal circumference, femur length, and crown-heel length measurements were made. Regression analyses were used to determine the effect on each measurement of maternal race, height, body mass index, hypertension, weight gain, smoking, previous low birth weight, and fetal sex.

RESULTS

Acting through their effect on head circumference, abdominal circumference, and fetal length, each of the risk factors and female sex were shown to have a negative effect on fetal weight. The timing of the impact, its magnitude, and the specific anthropometric measurement affected were different for each of the risk factors.

CONCLUSIONS

The impact of maternal risk factors and fetal sex on estimated fetal weight has been demonstrated to occur first in specific gestational age windows and is mediated through effects on specific fetal anthropometric measurements.

Adolescent pregnancy: maternal weight effects on fetal heaviness: possible route to improved outcomes

In a previous report of a zinc supplementation trial in pregnant adolescents zinc effect varied according to maternal weight (wt) status--normal (90-110% of expected wt), light or heavy, prompting this analysis of effects of wt status and gestational wt gain on fetal heaviness relative to length and gestational age (GA) and other pregnancy outcomes. One-third of adolescents shifted in or out of normal wt by delivery, creating seven outcome groups--light-light, light to normal, normal to light, normal-normal, normal to heavy, heavy to normal, and heavy-heavy. These wt class change groups varied significantly as to intrauterine growth (SGA, low AGA, high AGA, and LGA); by weekly grams gain per cm height (ht), birth wt, infant wt/length ratio, and occurrence of low birth wt (LBW). Infants with above average intrauterine growth had an advantage in: absolute size, length of hospital stay, rates of LBW, fetal demise, rates of low Apgar score, and "other" complications. This association between intrauterine growth and maternal wt class change suggests that promotion of wt gain might lower rates of LBW. Birthwt varied by quartiles of weekly wt change (gm) per cm ht in women grouped by their percent of expected wt: in the lowest quartile (Q1) only one group in seven reached average Bwt (3025 grams); with Q4 gain all groups did. Thus, the parameter wt gain/wk/cm ht deserves study as a tool for monitoring wt status and gain to identify those pregnant adolescents in greatest need for nutritional counseling and to set wt gain goals.

Women who gain more fat during pregnancy may not have bigger babies: implications for recommended weight gain during pregnancy

The correlation between infant birthweight and the amount of fat gained during pregnancy (estimated as the change in maternal weight between 10 weeks gestation and 2-3 weeks postpartum) was studied in 115 healthy, parous, urban Scottish housewives. There was very little correlation between these variables (r = 0.13, falling to r = 0.07 after birthweight was adjusted for initial maternal weight and length of gestation), i.e., women who gained more fat during their pregnancies did not give birth to heavier babies. This suggests that for most women one of the principal effects of increasing food intake during pregnancy may be to increase maternal fat gain rather than promote fetal growth, and that efforts to increase birthweight by encouraging greater weight gain during pregnancy may be unsuccessful.

Patterns of maternal weight gain in pregnancy

A retrospective study of 1145 pregnant women showed that trends in mean maternal weight gain from the time of booking until delivery were not linear. Statistically significant lower rates of maternal weight gain were seen before 16 weeks, after 36 weeks and between 28 and 32 weeks gestation (P less than 0.05). The mean maternal weight gain was 10.71 kg (SD 4.3) and the mean weekly weight gain was 0.38 kg (SD 0.16). A wide variation of maternal weight gain was seen in women with a normal outcome. The mean weight gain in heavy (greater than 68 kg) and light (less than 55.4 kg) women was less than that in women whose weight was in the third quartile (60-68 kg, P less than 0.05). The mean maternal weight gain was less in young (less than 20 years) women than in older women (greater than 25 years; P less than 0.05), less in parous than in primigravid women from week 37 onwards (P less than 0.05), less in smokers than in non-smokers from 20 weeks onwards (P less than 0.05), and greater in hypertensive women (BP less than 140/90) than in normotensive women (P less than 0.05) from week 24 onwards. The mean weight gain in women who had small for gestational age (SGA) infants was not significantly different from that in women who had infants that were of appropriate size for gestational age. After taking into account infant and placental weight using multiple regression analysis, the factors that were associated with statistically significant differences in average weekly weight gain were parity, body mass index, smoking habit and raised blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Low birthweight in Riyadh, Saudi Arabia: incidence and risk factors

In a multicentre prospective study, we have determined the incidence of low birthweight (LBW) and the main predisposing risk factors. Among 4651 consecutive births over a 5-month period in five hospitals in Riyadh, the overall incidence of LBW was 8.4%. When stillbirths were excluded the incidence of LBW was 7.4% of all live births. Statistical analysis was performed among 638 births (319 LBW infants, i.e. less than or equal to 2499 g and 319 babies weighing 2500 g or more). Of the 28 antenatal risk variables analysed, 13 were found to be significant when studied separately. Of these 13 variables, six were found to be significant predictors of LBW, using stepwise multiple logistic regression. These six variables together correctly predicted 72% and 88% of the LBW babies or normal birthweight babies, respectively. The risk factors thus identified were (i) short gestation, (ii) multiple gestation, (iii) low maternal body mass index, (iv) nulliparity, (v) availability of housework help, and (vi) absence of consanguinity. Measures for reducing these factors are also discussed.

Epidemiology of prematurity

The two components of low birth weight — preterm delivery and fetal growth retardation — lead singly or in combination to a heavy burden of mortality, short- and long-term morbidity, and high medical and social costs. Although different types of long-term morbidity are still being identified, the primary focus of concern has been neurodevelopmental disability resulting from the cerebral palsies, hydrocephalus, and visual and auditory deficits among survivors of very low birth weight. Additional special risks in such infants include chronic lung disease, acute lower respiratory infections, and rehospitalization in infancy and early childhood.

Smoking, maternal age, fetal growth, and gestational age at delivery

The relationship between smoking and maternal age and their combined effects on birth weight, intrauterine growth retardation, and preterm delivery were studied. Smoking lowers birth weight both by decreasing fetal growth and by lowering gestational age at delivery. However, the effect of smoking on both fetal growth and gestational age is significantly greater as maternal age advances. In a multiple logistic regression model adjusting for race, parity, marital status, maternal weight, weight gain, and alcohol use, smoking was associated with a fivefold increased risk of growth retardation in women older than 35 but less than a twofold increased risk in women younger than 17. Smoking reduced birth weight by 134 gm in young women but 301 gm in women older than 35. Smoking in older women also was associated with more instances of preterm delivery and a lower mean gestational age when compared to women 25 or younger.

Maternal determinants of birthweight in normal pregnancy

Partial and multiple regression analysis was performed to find out the correlation between birthweight and maternal anthropometric variables. Pearson regression analysis revealed significant dependence of birthweight on gestation of pregnancy, maternal weight, symphysis-sternal distance and height, but not on armspan and skin thickness. However, the only maternal variable bearing significant influence on birthweight in partial regression analysis was bodyweight. The effects of maternal determinants on birthweight, though some of them were statistically significant, were clinically unimportant.

Weight percentile at birth. I. Clinical data of pregnancy and relevance for early childhood development

The influence of the weight percentile at birth on childhood development was examined in a prospective study of 847 singleton pregnancies. In the first two years of life significant relationships between the birth weight percentiles and the infant's development could be proven, while at the age of four social factors were predominant. Though various clinical data in pregnancy and delivery were related to fetal growth, such as weight of the mother, previous abortions and diseases, additional biochemical and biophysical information is desirable for early recognition of intrauterine growth disorders.

Accuracy of mothers' recall of birthweight and gestational age

Information on the birthweight and gestational age of previous siblings is usually dependent upon maternal recall. This information is of importance in assessing the current risk of perinatal morbidity and mortality. The validity of maternal recall of birthweight and gestational age of 880 children born to 97 multiparas was examined by comparison with hospital records. About 75% of all reported birthweights were accurate to within 100 g and a similar proportion of reported gestational ages was correct to within 1 week. Recall was most accurate for most recent births as well as for earliest births and was not related to maternal age or education. There was a tendency for the smallness of low birthweight infants to be exaggerated by mothers. We conclude that within defined limitations, maternal recall of birthweight and gestational age of previous children is sufficiently accurate for clinical and even for epidemiological use.

A comparison of the effects of prenatal exposure to tobacco, alcohol, cannabis and caffeine on birth size and subsequent growth

Maternal use of cigarettes, alcohol, cannabis, and caffeine was established for four time periods; prepregnancy, first trimester, third trimester and average use over pregnancy. The relationship between such usage and growth parameters of offspring followed up from birth to 12 and 24 months of age were examined. Of the soft drugs used, nicotine had the most pronounced effect. After adjustment for other relevant variables, nicotine use prior to and during pregnancy was negatively related to weight and head circumference at birth. Furthermore, third trimester nicotine use was a stronger predictor of decreased weight and head circumference at birth than was first trimester use. The results obtained are consistent with ponderal index (PI) literature suggesting a recovery of growth retardation in infants with a lowered PI. Average consumption of greater than one ounce of absolute alcohol per day was negatively related to birth weight and length. Neither cannabis nor caffeine use had a significant negative effect on any growth parameter.

Small-for-gestational age births in successive pregnancy outcomes: results from a longitudinal study of births in Norway

In this population-based study, a strong tendency to repeat small-for-gestational age (SGA) deliveries in successive births has been documented. Mothers who showed this tendency ('repeater mothers') differed from mothers who had only one SGA delivery in their first three single births. In the group of mothers with only one SGA birth, there was an association between the SGA birth and such pregnancy complications as preeclampsia, vaginal bleeding, and placental pathologies. No similar association with medical complications during pregnancy was found for the repeater mothers. Instead, these mothers were characterized by lower educational attainment and lower socio-economic status based on husbands' occupational groupings. Thus, the tendency to repeat SGA birth appears to be mediated in part through more adverse living conditions and lifestyle habits.