Maternal risk factors for preterm birth and low birthweight in Cape Verde

BACKGROUND: Fifteen years after the implementation of an antenatal risk screening program in Cape Verde, the first assessment of an association between maternal obstetric characteristics and preterm birth or low birthweight (LBW) infants was undertaken. METHODS: A cohort of 353 systematically selected antenatal clinic attenders in the county of Praia, Cape Verde, was studied prospectively during the period October 1991 through December 1992. The cohort was followed past the perinatal period and information was obtained according to a pretested structured questionnaire. In the analysis of preterm birth and LBW, multiple logistic regression was listed to estimate the relative risks of ll background variables. RESULTS: The prevalence of preterm birth (<37 gestational weeks) was 12%, and the prevalence of LBW infants was 8%. Low birthweight (<2500 grams) was significantly associated with low maternal age (< or = 19 years, RR=3.7); nulliparity (RR=5.2) and obstetric history of previous LBW infant (RR-6.5). The risk of preterm birth was significantly increased if the woman had an obstetric history of hypertension or convulsions (RR=2.6). CONCLUSIONS: In the setting studied, teenage women and women with previous pregnancy hypertension should be given selective attention in antenatal care to achieve improved pregnancy outcome. Primary prevention is needed to lower the prevalence of teenage pregnancies.     

The effect of smoking cessation during pregnancy on preterm delivery and low birthweight

BACKGROUND: Evidence exists that maternal cigarette smoking is associated with preterm birth. Our purpose was to investigate the relation between maternal smoking cessation at different points during pregnancy and the preterm delivery rate and low birthweight. METHODS: Data from the 1988 National Health Interview Survey were analyzed. The study included women who gave birth to children within 6 years of the 1988 interview date (N = 4876). Preterm delivery and infant low birthweight were the main outcome measures. These measures were compared with maternal smoking status during pregnancy. Logistic regression models were computed to control for maternal age at the time of birth, parity, race, and total family income. RESULTS: Women who did not smoke cigarettes during pregnancy were less likely to give birth prematurely (5.9% vs 8.2%, P = .003) or give birth to a low-birthweight baby (5.5% vs 8.9%, P < .001) than women who smoked at some time during the year before giving birth. A significant association existed between maternal smoking status and both preterm delivery and low birthweight. Compared with those who smoked beyond the first trimester, those who quit smoking within the first trimester had reductions in the proportion of preterm deliveries (6.7% vs 9.1%) and low birthweight infants (7.9% vs 9.6%). CONCLUSIONS: Low birthweight and preterm delivery are reduced in women who stop smoking in the first trimester of pregnancy.     

Ethnic differences in the sudden infant death syndrome: what we can learn from immigrants to the UK

AIMS: To compare the effect of potential maternal and birth factors on rates of sudden infant death syndrome (SIDS) within and between infants born to mothers of different ethnic groups. METHODS: Routinely collected obstetric, child health data relating to 39,101 residents of three East London Districts born in 1989-1990 were obtained. These were matched with 312 death registration records to validate death and add registered cause of death. Mortality rates were calculated in the usual way, and using life-table methods. RESULTS: These related to six ethnic groups, the largest of which were Anglo-European and Bangladeshi. Low birth-weight was the only factor associated with a greater risk of SIDS in all ethnic groups. Maternal smoking was uncommon amongst all Asian groups and African mothers, and rates of SIDS were uniformly low amongst non-smokers in all ethnic groups except Pakistanis. Adjustment for maternal age, parity, gestational age and birthweight would widen the differences between risk of SIDS observed between Anglo-Europeans and Bangladeshi infants. CONCLUSIONS: The study has demonstrated that local data is more timely and of greater detail than that available nationally. Of the risk factors considered, smoking reported during pregnancy is the most commonly encountered and is particularly associated with deaths attributed to SIDS.     

Intrauterine nutrition

Foetal or intrauterine nutrition is a subject of increasing interest. There are two main reasons for this. The first one is the observation that being born small for gestational age is associated with increased risk of cardiovascular disease and diabetes later in life. The second one is the discovery that nutritional factors directly influence activity of genes. If nutritional inadequacies in the foetal period permanently alter the expression of genes, the individual's susceptibility to perinatal complications and diseases later in life may be altered. The main causes of intrauterine malnutrition are poor maternal diet, placental insufficiency, and impaired foetal usage of nutrients. The consequences of foetal malnutrition may include intrauterine growth retardation, congenital malformation, a variety of neurological dysfunctions, susceptibility to birth asphyxia, and diseases later in life; all of these are important determinants of health throughout life.     

Familial and perinatal risk factors for micro- and macroalbuminuria in young IDDM patients

It has been suggested that hereditary risk for hypertension and cardiovascular disease (CVD) as well as intrauterine growth may be involved in the pathogenesis of diabetic nephropathy. In the present study, we investigated the influence of familial and perinatal risk factors on the occurrence of micro- and macroalbuminuria in young IDDM patients. A cohort of 1,150 young patients with > or =5 years' duration of IDDM was screened for microalbuminuria. Data on family history of hypertension, CVD, IDDM, and NIDDM; perinatal factors such as birth weight, gestational age, and duration of breastfeeding; and maternal education, smoking, hypertension, and proteinuria during pregnancy were collected. We identified 75 patients with an albumin excretion rate > or =15 microg/min in more than two overnight urinary samples and compared them in a nested case-control study with three normoalbuminuric control subjects per patient from the same cohort, matched for diabetes duration. Perinatal factors were analyzed in all patients born at term (+/- 2 weeks), 59 of the 75 patients and 155 of the 225 control subjects. In univariate analysis, hypertension in parents (odds ratio [OR] 4.21), CVD in parents and grandparents (OR 1.26), maternal smoking during pregnancy (OR 3.21), and a low level of maternal education (OR 2.33) were significantly associated with the development of micro- and macroalbuminuria. When adjusted for other familial and perinatal factors, current mean blood pressure, HbA1c, smoking, BMI, sex, age, and postpubertal diabetes duration, using logistic regression analyses, only parental hypertension in all patients and maternal smoking during pregnancy and low level of maternal education in full-term patients were independent risk factors. When patients with poor glycemic control were analyzed separately, familial CVD, poor metabolic control, parental hypertension, maternal smoking during pregnancy, and level of maternal education were independent risk factors, with the adjusted OR markedly increased, compared with the matched subgroup with better HbA1c. In conclusion, familial hypertension and CVD, maternal smoking during pregnancy, and low level of maternal education may independently increase the risk for incipient nephropathy in full-term offspring who later develop IDDM. Current poor glycemic control seemed to increase the effect of these risk factors.     

Differential effects of maternal heroin and methadone use on birthweight

An analysis of birthweights of 337 neonates in relation to history of maternal narcotic usage was undertaken. Mean birthweight of infants born to mothers abusing heroin during the pregnancy was 2,490 gm, an effect primarily of intrauterine growth retardation. Low mean birthweight (2,615 gm) was also seen in infants born to mothers who had abused heroin only prior to this pregnancy, and mothers who had used both heroin and methadone during the pregnancy (2,535 gm). Infants born to mothers on methadone maintenance during the pregnancy had significantly higher mean birthweights (2.961 gm), but lower than the control group (3,176 gm). A highly significant relationship was observed between maternal methadone dosage in the first trimester and birthweight, i.e., the higher the dosage, the larger the infant. Heroin causes fetal growth retardation, an effect which may persist beyond the period of addiction. Methadone may promote fetal growth in a dose-related fashion after maternal use of heroin.     

Risk factors for protein-energy malnutrition in pre-school shantytown children in S?o Paulo, Brazil

OBJECTIVES: To investigate the health and nutritional conditions of people living in a shantytown in the city of S?o Paulo in order to identify risk factors for infant malnutrition. DESIGN: A retrospective cohort study. PARTICIPANTS: Children living in a shantytown was conducted among children less than 72 months of age. METHODS: Home visits were made and information was collected regarding the risk factors for malnutrition. RESULTS: The prevalence of chronic malnutrition was 41.6% according to Gomez, 36.6% according to Waterlow, and 17.6% according to WHO. Risk factors for malnutrition, according to the weight-for-age index, included birthweight, presence of upper respiratory tract infections, number of pregnancies, number of births, maternal body mass index, birthplace of father, and home building material; according to the weight-for-height index, they included birthweight and maternal age at the time of birth; and according to the height-for-age index, they included the number of prenatal medical visits, birthweight, maternal height, maternal body mass index, father's employment being unregistered, and maternal birthplace. An instrument for identifying children at risk of malnutrition was devised from these major risk factors for future malnutrition, which may then be applied to newly-born children.     

Neonatal polycythemia in appropriately grown infants of hypertensive mothers

Neonatal polycythemia is a frequent finding after pregnancies complicated by diabetes and by maternal hypertension with intrauterine growth retardation (IUGR). It is still unclear if the association of polycythemia with hypertension is the result of IUGR or of hypertension per se. To establish the incidence of neonatal polycythemia in populations at risk, we analyzed the results of hematocrit values obtained from 1592 neonates born consecutively at the Hospital de Clinicas, Buenos Aires. Capillary hematocrit values were obtained by heel stick before 6 h of age. When the values were 65% or greater, new samples were obtained from an antecubital vein. The risk of polycythemia in appropriately grown infants of hypertensive mothers was 12.6-fold greater than the risk in the general population. These data show that maternal hypertension poses a significant risk for polycythemia, regardless of fetal growth. We suggest that, to prevent possible sequela, hematocrit is measured routinely in all infants of hypertensive mothers for prompt diagnosis and treatment.     

Fetal malnutrition: an appraisal of correlated factors

Fetal malnutrition has emerged as a significant health problem over the past decade. Present evidence suggests that maternal environment plays the major etiologic role in fetal malnutrition. The association of fetal malnutrition in mothers with chronic hypertension is well known, but fetal malnutrition is associated with maternal hypertension in less than 25 per cent of cases. Among a group of 182 pregnant women studied at midpregnancy for blood levels of vitamins, trace metals, proteins, amino acids, and parameters of maternal leukocyte energy metabolism, it was found that the concentration of 10 amino acids, alpha-1-globulin, zinc, and total carotenes had a statistically significant relationship to fetal growth. Similarly significant correlations were found for maternal leukocyte adenosine disphosphate, phosphofructokinase activity, ribonucleic acid (RNA) synthesis, and cell size. Maternal cigarette smoking was correlated with reduced fetal growth. Analysis showed that there was a significant reduction in leukocyte RNA synthesis and phosphokinase activity and in the plasma levels of 14 amino acids, and carotene in smoking mothers. This information lends support to the hypothesis that factors which affect the growth of fetal cells also will affect maternal leukocytes in a definable way.     

Co-trimoxazole and stavudine interference in a high-performance liquid chromatographic analysis for didanosine in human plasma

We have analysed birthweights of 4,508 Aboriginal and Torres Strait Islander livebirths in the Kimberley region of Western Australia from 1981-93. Mean birthweight varied significantly according to month of birth (F(11) = 2.57, p = 0.003) and low birthweight babies were more common during the wet season. A significant increase in the proportion of very low birthweight (VLBW) babies was observed during the wet season compared with the dry season (OR 2.73; 95% CI 2.3-3.67; p < 0.001); whereas babies weighing 1,500-2,499 g were not significantly more common during the wet season (OR 1.06; 95% CI 0.96-1.17; p = ns). The results indicate that adverse environmental conditions may be associated with increased risk of VLBW. Since newborns weighing less than 1500 g are very likely to be pre-term (< 37 weeks' gestation), the findings also suggest that seasonality of birthweight may be due to an increase in pre-term births rather than an increase in intrauterine growth retardation. Further research is required to identify the underlying causes of an increase in VLBW babies during the wet season.     

Local low-dose interleukin-2 induces systemic immunity when combined with radiotherapy of cancer. A pre-clinical study

OBJECTIVES: This study examined whether the decline in birth-weight with increasing altitude is due to an independent effect of altitude or an exacerbation of other risk factors. METHODS: Maternal, paternal, and infant characteristics were obtained from 3836 Colorado birth certificates from 1989 through 1991. Average altitude of residence for each county was determined. RESULTS: None of the characteristics related to birthweight (gestational age, maternal weight gain, parity, smoking, prenatal care visits, hypertension, previous small-for-gestational-age infant, female newborn) interacted with the effect of altitude. Birthweight declined an average of 102 g per 3300 ft (1000 m) elevation when the other characteristics were taken into account, increasing the percentage of low birthweight by 54% from the lowest to the highest elevations in Colorado. CONCLUSIONS: High altitude acts independently from other factors to reduce birthweight and accounts for Colorado's high rate of low birthweight.     

Selection and identification of single domain antibody fragments from camel heavy-chain antibodies

OBJECTIVE: Our purpose was to determine whether women who were themselves small for gestational age at birth are at risk of giving birth to a small-for-gestational-age child and whether women who were themselves preterm at birth are at risk for preterm delivery. STUDY DESIGN: Women born in Copenhagen as subjects in the Danish Perinatal Study (1959 to 1961) were traced through the Danish Population Register. Information was obtained on their pregnancies during 1974 through 1989. RESULTS: A total of 25% of the children of small-for-gestational-age women were small for gestational age compared with 11% of the children of non-small-for-gestational-age women. Eleven percent of the children of preterm women were preterm compared with 7% of the children of women born at term. The adjusted odds ratios were 2.0 (95% confidence interval 1.4 to 3.0) for women who were small for gestational age to have small-for-gestational-age children and 1.5 (95% confidence interval 0.9 to 2.5) for women who were born preterm to have preterm children. Small-for-gestational-age women were not at significantly increased risk of preterm delivery (odds ratio 1.2), and preterm women were not at significantly increased risk of having small-for-gestational-age children (odds ratio 1.3). CONCLUSIONS: Reduced intrauterine growth of the mother is a risk factor for reduced intrauterine growth of her children. However, preterm birth of the mother is not strongly associated with preterm birth of her children.     

Risk factors for low birth weight and intrauterine growth retardation in Santiago, Chile

An epidemiologic case-control study to ascertain the determinants of low birthweight was carried out in Santiago, Chile, from January to December 1989. The cases were defined as livebirths < 2500 g. The controls were livebirths > or = 2500 g of birthweight. All cases and a random sample (1:1) of controls were selected among 8,254 singleton births occurring at the El Salvador Hospital in the Eastern area of Santiago. These deliveries represented 50% of institutional deliveries in the area. Home deliveries (2%) and private hospital deliveries were not included in the study. Information was obtained from hospital medical records by six trained medical students. Some information could not be obtained from the hospital medical records. Thus the second step in data collection was the tracking of all the selected subjects to their referring neighborhood health centers. For the analysis, the data were divided into 3 case (outcome) categories: 453 subjects were the total case group. From these, 153 were the IUGR case group and 300 were the LBW preterm case group. The general control group consisted of 605 normal birthweight infants. 565 were the IUGR control group and 40 were the preterm control group. A total of 25 risk factors showed a significant crude odds ratio for at least one of the groups. In the multivariate logistic regression analysis eight variables: No. of pregnancies, previous adverse outcomes, previous LBW, pregnancy maternal weight, No. of visits, month of first prenatal care visit, maternal smoking and intrahepatic cholestasis of pregnancy, were significantly associated with LBW after adjustment by confounding. Eight risk factors: IUGR in previous pregnancies, Previous adverse outcome, Maternal smoking, intrahepatic cholestasis, maternal pregnancy weight, maternal height, month first prenatal visit, No. of visit, were significant to IUGR. Only two variables: pregnancy weight, divorced mother, were significantly associated with low birth weight in the preterm group. The most relevant risk factors were included in stepwise logistic regression models carried out for the outcome LBW for the general group, term group and preterm group, in order to adjust by confounding. Adjusted odds ratios were then obtained. Prenatal care related factors and maternal adverse obstetric factors were at higher significance for LBW in the general and IUGR groups. Only nutritional factors were related to LBW in preterm group. Women who delivered a LBW or IUGR infant were more likely to have fewer pregnancies, a history of previous LBW, lower prepregnancy weight and lower gestational weight gain. ICP was associated with an elevated risk of LBW that was independent of gestational age.     

Prenatal risk factors for cryptorchidism: a record linkage study

Using data from the Oxford Record Linkage Study (ORLS), we conducted a case-control study to examine prenatal risk factors for cryptorchidism. We identified 1449 boys born during 1970-86 for whom there was a record of an orchidopexy during 1970-87. Up to eight controls were matched to each case on year of birth and hospital or place of delivery. For each boy and his mother we extracted abstracts of maternity and general hospital records from the ORLS. Low birthweight (trend P < 0.001), low social class (trend P < 0.001), breech presentation (relative risk 1.67; 95% confidence interval [CI] 1.16, 2.41), pre-eclampsia (1.17 [1.00, 1.37]), artificial feeding (1.22 [1.04, 1.45]) and episiotomy (1.13 [1.00, 1.27]) were identified as independent risk factors for cryptorchidism. Gestational age was not independently associated with cryptorchidism after adjusting for birthweight (P = 0.33), and this observation suggested that some cryptorchid boys may have suffered from intrauterine growth retardation. Low birthweight, breech presentation and pre-eclampsia may have in common poor placental function and impaired fetal growth, which may be causes of cryptorchidism.     

Increased birth weights in the Nordic countries. A growing proportion of neonates weigh more than four kilos

The proportion of children with high birthweights is increasing in Sweden, as in the other Nordic countries. According to the Swedish national birth registry (founded in 1973), the proportion of term (i.e. (37 gestational weeks) offspring of singelton pregnancies, and weighing four kg or more, increased from 16.9 per cent in 1973 to 20.3 per cent in 1995. The respective figures for the first-born subgroup were 12.9 and 15 per cent, the increase in mean birthweight being from 3400 to 3520 g. There was a corresponding increase in head circumference. The risk of delivery-related complications increases with birthweight over four kg, and a higher incidence of major perineal rupture (grade 3 or 4) has been reported, as well as a disturbing increase in the incidence of brachial plexus damage. Findings in recent studies suggest high birthweight to be associated with an increased risk of subsequent morbidity, both in childhood and in adulthood, specifically diabetes type 1, eczema and certain malignancies, particularly breast cancer and prostate cancer. Although the cause of the increasing proportion of large newborns is not known, it may be partly due to weight increase among gravidae. Another possible explanation is reduced maternal smoking, as smoking is less common now than in the 1970s.     

Low birth weight is associated with non-insulin-dependent diabetes mellitus in discordant monozygotic and dizygotic twins

Previous studies have demonstrated an association between low weight at birth and risk of later development of non-insulin dependent diabetes mellitus (NIDDM). It is unknown whether this association may be due to an impact of intrauterine malnutrition per se, or whether it may be due to a coincidence between the putative "NIDDM susceptibility genotype" and a genetically determined low weight at birth. We traced original midwife birthweight record determinations in a group of monozygotic (n = 14 pairs) and dizygotic (n = 14 pairs) twins who phenotypically appeared discordant for NIDDM at a mean age of 67 and 64 years respectively. Birthweights were lower in the NIDDM twins compared with both their identical and non-identical non-diabetic co-twins respectively (p < 0.02 both). Using a similar approach in twin pairs discordant for impaired glucose tolerance (IGT) per se, no significantly decreased birthweight was detected in the IGT twins compared with their non-diabetic co-twins. However, when a larger group of twins with different glucose tolerances were considered, birthweights were lower in twins with abnormal glucose tolerance including both NIDDM and IGT. Furthermore, the twins with the lowest birthweights among the two co-twins had the highest plasma glucose concentrations 120 min after the 75 g oral glucose load (n = 86 pairs, p = 0.02). The study supports the hypothesis that low birthweight and a non-genetically determined intrauterine component such af malnutrition may play a role for the development of NIDDM in twins.     

Is maternal malnutrition associated with a low sex ratio at birth?

The low male/female ratio at birth in African populations has been attributed to a variety of genetic, behavioral, and environmental factors. A low sex ratio at birth has been associated with maternal malnutrition in mammals, but this issue has not been studied in humans. In this study we analyzed the relation between maternal nutritional status and sex ratio at birth in 3282 children born to 684 women from a rural African society. Short maternal stature and obesity were independently related to a low sex ratio at birth. These results are consistent with animal experiments that indicate an adverse effect of maternal malnutrition on male fetuses. The results warrant further research in this area.     

Food-borne outbreak of streptococcal pharyngitis in an Israeli Airforce Base

OBJECTIVE: To determine if maternal hematocrit and serum albumin can predict intrauterine growth retardation and/or preterm delivery. METHODS: Analyses were performed during each trimester of pregnancy to evaluate the predictive value of these two common laboratory parameters as predictors of intrauterine growth retardation and/or prematurity. RESULTS: 1468 women participated in the study. Intrauterine growth retardation occurred in 9.9% and preterm delivery in 6.1%. A significant inverse correlation between hematocrit and albumin and birth weight was found (r = -0.005, p = 0.04, and r = -0.07, p = 0.007, respectively), albumin being a stronger predictor as demonstrated by multiple regression. Low hematocrit at the third visit was associated with a longer pregnancy duration (r = -0.06, p = 0.02). Woman with higher serum albumin levels at the second visit, had a longer pregnancy duration, possibly reflecting a better nutritional status (r = 0.057, p = 0.03). To determine the predictive value of hematocrit and serum albumin, the prevalence of intrauterine growth retardation and premature delivery in the highest quartiles were compared with the lowest, and no significant differences were observed (p > 0.1). CONCLUSION: Maternal hematocrit and serum albumin concentration cannot be used as useful predictors of intrauterine growth retardation or preterm delivery.     

Differential effects of preterm birth and small gestational age on cognitive and motor development

AIMS: To determine the differential effects of preterm birth and being small for gestational age on the cognitive and motor ability of the child. METHODS: A longitudinal cohort of all infants of gestational age < or = 32 weeks born to mothers resident in the counties of Cheshire and Merseyside in 1980-1 was studied. The children were assessed at the age of 8 to 9 years using the Wechsler Intelligence Scale for Children, the Neale analysis of reading ability, and the Stott-Moyes-Henderson test of motor impairment. Adequacy of fetal growth was determined by the birthweight ratio--that is, the ratio of the observed birthweight to the expected birthweight for a given gestational age. Children with clinically diagnosed motor, learning or sensory disabilities were excluded. Information on social variables was obtained by a questionnaire completed by the parents. Of the 182 children, 158 were assessed. RESULTS: IQ was positively correlated with birthweight ratio but not with birthweight or gestational age. Motor ability was associated with birthweight, gestational age, and birthweight ratio. Reading comprehension was associated with birthweight ratio, but reading rate and accuracy were best explained by social variables and sex. IQ remained associated with birthweight ratio, after adjusting for maternal education, housing status, and number of social service benefits received. Reading ability was related to these social variables but motor ability was not. CONCLUSIONS: The effects of SGA and preterm birth differed: SGA was associated with cognitive ability, as measured by IQ and reading comprehension; motor ability was additionally associated with preterm birth. Reading rate and accuracy were not associated with SGA or preterm birth but were socially determined.     

Offspring birth weights after maternal intrauterine undernutrition: a comparison within sibships

The authors examined the effects of maternal intrauterine undernutrition on offspring birth weights in a cohort of women born between August 1944 and April 1946 in Amsterdam, The Netherlands. This period included the Dutch Hunger Winter, a war-induced famine. Undernutrition was defined separately for each trimester of pregnancy as an average supply of less than 1,000 calories per day from government food rations. For maximum control of potential maternal confounding factors related to offspring birth weight, the authors performed a within-family analysis, including 437 families with two siblings and 107 families with three siblings born between 1960 and 1985. As in other studies of the famine, maternal birth weight itself was decreased after third trimester intrauterine exposure but not after first trimester exposure. The expected increase in offspring birth weights with increasing birth order was not seen after maternal intrauterine exposure in the first trimester of pregnancy. In this group, second born infants weighed, on average, 252 g less at birth than their firstborn siblings (95% confidence interval (CI) -419 to -85), and thirdborn infants weighed 419 g less (95% CI -926 to 87), even after adjustment for trimester of maternal intrauterine exposure, maternal birth weight, smoking during pregnancy, and sex of infants in the sibling pairs. Additional adjustment for the birth weight of the elder sibling did not materially change this abnormal pattern. There were no abnormal patterns in offspring birth weights after maternal intrauterine exposure in the second or third trimester of pregnancy. The study outcomes could not be explained by other selected determinants of birth weight, by lack of control for socioeconomic status, or by loss to follow-up of the 1944-1946 birth cohort. This study suggests that there may be long-term biologic effects, even into the next generation, of maternal intrauterine undernutrition which do not correspond to the effects on the mothers' own birth weights.