Difference In Mean Birth Weight Research Articles

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

STUDY OBJECTIVE: To analyse factors associated with birth weight and to evaluate the validity of obstetrical data. DESIGN: Obstetrical data were retrieved for singleton men born in 1913 and living...

High protein supplementation in pregnancy.

To assess the effects of providing pregnant women with high-protein nutritional supplements on gestational weight gain and on the outcome of pregnancy, including fetal growth, gestational duration, and maternal and fetal/infant morbidity and mortality. The register of clinical trials maintained and updated by the Cochrane Pregnancy and Childbirth Group. All acceptably controlled comparisons of protein/energy supplementation in which the protein content of the supplement provided >25% of its total energy content. Data were extracted by the author from published reports, and supplemented by additional information from trialists contacted by the author. Two studies involving 1076 women were included. High protein supplementation was associated with a small, statistically nonsignificant increase in weekly maternal weight gain. The two available trials provide no evidence of benefit on fetal growth; indeed, the adjusted mean difference in birth weight is -58. 4 g. One trial also reported a nonsignificantly increased risk of neonatal death with high-protein supplementation. There is not enough evidence to evaluate the use of high protein supplementation in pregnancy.

Chronic lung disease following neonatal ventilation. I. incidence in two geographically defined populations.

The objective of this study was to compare the incidence of chronic lung disease following neonatal ventilation in two geographically defined populations. Prospective data collection was carried out over a 1 year period from March 11, 1990 to February 28, 1991 in the Trent Health Region (England) and in British Columbia, Canada. All infants < or = 32 weeks gestation and/or < or = 1500 g birthweight born to mothers normally resident in either the Trent Health Region or British Columbia were included. The main outcome measures were mortality rate, presence of chronic lung disease, days of ventilation, and oxygen used by each infant. The proportion of shortened gestation, low birthweight babies was 1.5% in Trent and 1.2% in British Columbia (957 of 63,350 births in Trent and 526 of 45,333 births in British Columbia). There were no significant differences in mean birthweight or gestation between the two cohorts, but there was a trend towards lower mortality for infants 750-1500 g birthweight in British Columbia. The incidence of chronic lung disease (using either of two definitions) was significantly higher in British Columbia, with a corresponding greater amount of respiratory care required. This occurred despite higher use of antenatal steroids and surfactant therapy in the British Columbia group. We conclude that there are important clinical and resource implications resulting from the number of ventilator and oxygen days used by the preterm population in terms of planning of neonatal services. The role of individual treatment modalities in producing differences in the incidence of chronic lung disease warrants further study in the setting of a geographically defined population.

A study on the health status of twin babies.

A study on twin births was conducted from May 1993 to April 1994 at S.A.T. Hospital, Thiruvananthapuram. The twinning rate in this period was found as 17.33 per 1000 births. 79.6% babies in the twin pairs were of like sex and 20.4% were of unlike sex. The incidence of low birth weight twin babies in this study was 68.9%. There was no significant difference in the physical parameters (birth weight, body length and head circumference) of twin babies in relation to sex. The incidence of twin birth was higher among primipara mothers and in the mothers of age group 21 to 25 years. The first born baby (twin A) was found to be heavier than the second born baby (twin B) in 44.78% twin pairs and their mean birth weight difference was 438 g, while the second born baby (twin B) was found to be heavier than the first born (twin A) in 38.31% twin pairs and their mean birth weight difference was 291 g. Statistical analysis showed that the difference between the mean birth weight difference in the case of twin A > B was significantly greater when compared to that of twin A < B.

Birthweight differentials among Asian Americans.

This study examines differentials in mean birthweight and the risk for low birthweight among various Asian-American groups in New York State (n = 499,377). Using resident singleton live-birth records from New York State for 1985 and 1986, Asian-American births were compared with Black, American Indian, and White births. Multivariate ordinary least squares and logistic regression models were used to analyze ethnic differences. Compared with White births, the expected mean difference in birthweight was -115 g for Chinese, -235 g for Japanese, -164 g for Filipinos, -120 g for Blacks, and 74 g for American Indians. The risk for low birthweight was 45% higher for Filipinos and 49% higher for Blacks as compared with Whites. Results of this study suggest substantial heterogeneity in mean birthweight and risk for low birthweight among ethnic groups in general and the major Asian-American groups in particular. Interestingly, after controlling for ethnic differences in sociodemographic risk factors, Filipinos appear to resemble Blacks much more closely than they do their Japanese and Chinese counterparts with respect to risk for low birthweight.

Smoking habits and birthweights in two successive births in Sweden

A population-based longitudinal study of mothers and their first and second infant (both live and single) was conducted to investigate the change in smoking habits from one pregnancy to the next and the effect on infants' birthweights. Of the 57 732 women, 6% quit and 3% started to smoke, 61% were non-smokers and 18% were smokers during both pregnancies. Smoking information on 12% was missing. Compared with women who never smoked, the mean birthweight difference was higher among women who quit smoking and lower among women who started to smoke. Among women who quit smoking, the second birthweight was the same as among women who never smoked. The first infants of women who quit smoking were heavier than those of women who maintained smoking (3392 g vs. 3287 g). Every fourth smoker stopped smoking. Women who quit smoking differed from those who continued to smoke in terms of distribution of age and level of education. Moderate smokers quit smoking more often than heavy smokers.

A clinical trial of induction of labor versus expectant management in postterm pregnancy

OBJECTIVE: Management of the uncomplicated pregnancy prolonged beyond the estimated date of confinement is controversial, particularly when the cervix is unfavorable for induction. The benefit of reducing potential fetal risk with induction of labor must be balanced against the morbidity associated with this procedure. The objective of this study was to compare two strategies for managing postterm pregnancy (i.e., immediate induction and expectant mangement). STUDY DESIGN: Four hundred forty patients with uncomplicated pregnancies at 41 weeks' gestation were randomized to either immediate induction of labor (n = 265) or expectant management (n = 175). Patients with expectant management underwent nonstress testing and amnioic fluid volume assessment twice per week. Patients in the induction group underwent induction within 24 hours of randomization. To evaluate the efficacy of intracervical prostaglandin E2 gel, patients in the induction group were randomized in a 2:1 scheme to receive either 0.5 mg prostaglandin E2 gel or placebo gel intracervically 12 hours before induction of labor with oxytocin. RESULTS: The incidence of adverse perinatal outcome (neonatal seizures, intracranial hemorrhage, the need for mechanical ventilation, or nerve injury) was 1.5% in the induction group and 1% in the expectant management group (p > 0.05). There were no fetal deaths in either group. There were no differences in mean birth weight or the frequency of macrosomia (birth weight ≥ 4000 gm) between the two groups (p > 0.05). Regardless of parity, prostaglandin E2 intracervical gel was not more effective than placebo in ripening the cervix. The cesarean delivery rate was not significantly different in the expectant (18%), prostaglandin E2 gel (23%), or placebo gel (18%) groups. CONCLUSIONS: Adverse perinatal outcome in otherwise uncomplicated pregnancies of ≥41 weeks is very low with either of the management schemes described. Thus from the perspective of perinatal morbidity or mortality either management scheme is acceptable. (AM J OBSTET GYNECOL 1994;170:716-23.)

Self-Selection, Prenatal Care, and Birthweight among Blacks, Whites, and Hispanics in New York City

Most research on birth outcomes has found a direct relationship between appropriate prenatal care and increased birthweight. Researchers concede, however, that without a randomized design, which is clearly unethical, one cannot determine how much of the association is due to the medical intervention and how much is due to the characteristics of the women receiving the care. In short, the degree of selection bias is unknown and potentially substantial. In this paper we test for selection bias and estimate its direction and magnitude. We find that adjusted mean differences in birthweight between women who obtain intermediate as opposed to inadequate prenatal care substantially underestimate the effects of care that would be observed under random assignment. In particular, ordinary least squares estimates indicate that the gains to intermediate care are 113 grams for black infants, 76 grams for white infants and 92 grams for Hispanic infants. Under random assignment, black infants would experience gains of 130 grams, whites 234 grams, and Hispanics 183 grams. The gains for adequate as opposed to intermediate care are relatively minor. The results point to adverse selection in the demand for prenatal care.

The association between prenatal care and birth weight among women exposed to cocaine in New York City

Objectives — Although the association between antenatal cocaine use and adverse birth outcomes has been well documented, relatively little is known about interventions that may ameliorate these consequences. We therefore examined the relationship between prenatal care and birth weight among a population of prenatal cocaine users. Design — Population-based retrospective analysis. Patients — All single-gestation live births to white non-Hispanic, black non-Hispanic, and Hispanic residents of New York City who gave birth between 1988 and 1990 with a positive indication for cocaine recorded on birth certificates (N=7923). Main Outcome Measures — We contrasted mean birth weight and rates of low birth weight ( Main Results — Adjusted odds ratios of low birth weight for cocaine users with four prenatal care visits or more as compared with those who had none were 0.51 for blacks (95% confidence interval [CI], 0.44 to 0.59), 0.39 for whites (95% CI, 0.23 to 0.66), and 0.37 for Hispanics (95% CI, 0.28 to 0.48). Adjusted mean birth weight differences between users with four visits or more and those with none were 262 g for blacks (P Conclusions — The receipt of prenatal care among cocaine users is associated with significant improvements in birth weight. Enrollment of cocaine users in prenatal care may be an effective start to a more comprehensive approach to this problem.

The Association Between Prenatal Care and Birth Weight Among Women Exposed to Cocaine in New York City

Although the association between antenatal cocaine use and adverse birth outcomes has been well documented, relatively little is known about interventions that may ameliorate these consequences. We therefore examined the relationship between prenatal care and birth weight among a population of prenatal cocaine users. Population-based retrospective analysis. All single-gestation live births to white non-Hispanic, black non-Hispanic, and Hispanic residents of New York City who gave birth between 1988 and 1990 with a positive indication for cocaine recorded on birth certificates (N = 7923). We contrasted mean birth weight and rates of low birth weight (< 2500 g) among cocaine users with one to three prenatal care visits, four or more visits, and unknown numbers of visits with users who reported no prenatal care. We used ordinary least squares and logistic regression to control for age, parity, smoking, alcohol, other drugs, weight gain, prepregnancy weight, employment, marital status, participation in the Supplemental Food Program for Women, Infants and Children, and method of finance. Adjusted odds ratios of low birth weight for cocaine users with four prenatal care visits or more as compared with those who had none were 0.51 for blacks (95% confidence interval [CI], 0.44 to 0.59), 0.39 for whites (95% CI, 0.23 to 0.66), and 0.37 for Hispanics (95% CI, 0.28 to 0.48). Adjusted mean birth weight differences between users with four visits or more and those with none were 262 g for blacks (P < .001), 247 g for whites (P < .001), and 317 g for Hispanics (P < .001). The receipt of prenatal care among cocaine users is associated with significant improvements in birth weight. Enrollment of cocaine users in prenatal care may be an effective start to a more comprehensive approach to this problem.

Low-dose aspirin in prevention and treatment of intrauterine growth retardation and pregnancy-induced hypertension

Meta-analysis of data from several controlled trials has shown that low-dose aspirin reduces the risk of pregnancy-induced hypertension (PIH) and intrauterine growth retardation (IUGR) in women at high risk of these disorders. We have assessed the efficacy of low-dose aspirin in women judged to be at moderate risk.Women were included on prophylactic criteria— age under 18 or over 40 years, mild or moderate chronic hypertension (diastolic pressure between 90 and 110 mm Hg), nephropathy with normal renal function and blood pressure, history of PIH or IUGR, and twin pregnancy—or therapeutic criteria—PIH or early signs of IUGR in current pregnancy. Eligible women were randomly assigned treatment with 50 mg aspirin daily until delivery (583) or no treatment (523); 18 and 46 women, respectively, were lost to follow-up. The groups were well matched for baseline characteristics. We found no differences between the no-treatment and aspirin groups in numbers of spontaneous (5 vs 2) or therapeutic (1 vs2) abortions, stillbirths (14 vs 13), perinatal mortality (35·7 vs 28·6 per 1000 births), mean birthweight (2858 [SD 729] vs 2874 [795] g), proportion of infants with birthweights below the 10th centile (95 [18·3%] vs 117 [19·0%]), or births before 37 weeks' gestation (184 [35·6%] vs 209 [33·9%]). Nor did the groups differ in the frequency of PIH with or without proteinuria (51 [15·2%] vs 81 [19·3%]). There was no difference in mean birthweight between the treatment groups in separate analyses according to criteria for trial entry and week of gestation at randomisation.Our study gives little support to the notion that low-dose aspirin is beneficial in women at moderate risk of PIH or IUGR.

Childhood blood pressure, body build, and birthweight: geographical associations with cardiovascular mortality.

The aim was to examine whether blood pressure, body build, and birthweight differ between areas of England and Wales with widely differing adult cardiovascular mortality rates. This was a cross sectional survey of children in five towns with exceptionally high and five towns with exceptionally low current adult cardiovascular mortality. The study was a school based survey. 3842 children aged 5.0-7.5 years were selected by stratified random sampling of primary schools (response rate 76%). Blood pressure, pulse rate, height, and weight were measured and birthweight was assessed by maternal recall. Children in towns with high cardiovascular mortality rates were significantly shorter than those in towns with low cardiovascular mortality rates (mean difference 0.9 cm, 95% confidence interval 0.4 to 1.4 cm) and had slightly higher body mass indices (mean difference 0.12 kg/m2, 95% CI -0.03 to 0.27 kg/m2). Mean birthweights were slightly lower in high mortality towns (mean difference 34 g, 95% CI -10 to 78 g), while the proportion of children with low birthweight (< 2500 g) (8.1%) was significantly higher than that in low mortality towns (5.5%) (p = 0.005). Mean differences in blood pressure between high and low mortality towns were small and non-significant, even after adjustment for height. The differences in height between high and low mortality towns were largely independent of social class. However, differences in mean birthweight were markedly reduced once social class was taken into account. No geographical relationship between childhood blood pressure and adult cardiovascular mortality was detected. Although it is possible that the differences in mean height and body mass index between towns with differing adult cardiovascular mortality may have implications for future patterns of health in these towns, the absence of marked differences in birthweight and blood pressure suggests that hypotheses proposing a direct relationship between intrauterine experience and adult cardiovascular mortality will have limited relevance to geographical variation in cardiovascular disease in this generation.

Influence of HLA genotype on birth weight of patients with Turner syndrome

Growth failure starting before birth is a common characteristic in Turner syndrome, and its pathogenesis is still not completely explained. Experiments performed in mice and rats to test whether a genetic disparity between mothers and offspring and maternal immunological status have any influence on litter size have demonstrated that allogenic litters are significantly larger in size than genetically compatible ones. Studies in humans have given contrasting results, but some authors have found that heterozygosity at enzyme loci and in blood groups is positively correlated with intrauterine growth. HLA class I and II polymorphisms were defined in 53 patients with Turner syndrome and in their parents, and lymphocytotoxic antibody detection was performed in 36 mothers. These data were related to the patients' birth weight. The frequency of the HLA-B16 allele in patients with a birth weight greater than 10th centile was significantly higher in comparison with those less than 10th centile. HLA antigen sharing was present in 43 couples (81.1%). Mean birth weight was 2934 +/- 472 g in patients without HLA antigen parental sharing and 2721 +/- 529 g in those whose parents shared HLA antigens. The mean birth weight of the 10 patients whose parents do not share HLA antigens was significantly higher than that of the patients with parental HLA-B+ DR sharing (P less than 0.05) and not significantly highe than in those patients with parental HLA sharing at other HLA loci. Patients whose parents shared B+DR antigens also had significantly smaller birth weights than those with B and A+B+DR sharing (P less than 0.025 and P less than 0.025). No significant difference in mean birth weight was found in relation to other parameters, such as mother-child histocompatibility, HLA homozygosity and lymphocytotoxic production in the mothers.

Birth weights of infants of black and white mothers without pregnancy complications

An analysis of 10,159 normal spontaneous vaginal deliveries was performed to examine racial differences in mean birth weight of infants whose mothers were without antepartum or intrapartum medical complications of pregnancy. The study was limited to black and white infants of low-income mothers who were inborn, singleton, and weighed greater than or equal to 500 gm at birth. High-risk maternal transfer patients and patients with hypertension, toxemia, bacteriuria, pyelonephritis, renal failure, diabetes, anemia, polyhydramnios, oligohydramnios, prolapsed cord, vaginal bleeding, placenta previa, abruptio placentae, prolonged rupture of membranes, maternal fever on admission, amnionitis, sexually transmitted diseases, or fewer than five prenatal care visits were excluded. When statistically significant differences in demographic characteristics were controlled, black infants had an average birth weight 181 gm less than that of white infants.

Differences in Black and White Infant Birth Weights: The Role of Maternal Demographic Factors and Medical Complications of Pregnancy

In a retrospective study of 18,631 deliveries among women of low income, we examined the association of racial disparities in mean birth weight with population differences in maternal demographic characteristics and antepartum-intrapartum medical complications. The study population consisted of inborn, nonreferred, singleton, low-income patients delivered on the nonprivate service after at least five prenatal care visits. Repeat cesarean sections were not included. The mean birth weight for black infants was 214 g less than that for white infants. Black and white mothers differed significantly in marital status, age, and years of education. Black and white mothers also differed significantly in the incidence of chronic hypertension, preeclampsia-eclampsia, anemia, amnionitis, fever on admission, and sexually transmitted diseases. In this population, controlling for maternal demographic characteristics and medical complications of pregnancy produced a predicted mean birth weight for black infants that was 100 g less than that for white infants (53% of the observed racial difference in mean birth weight).

Does Spousal Physical Abuse Affect the Outcome of Pregnancy?

The relationship between living in a physical abusive relationship and adverse outcome of pregnancy was examined using a structured interview including an obstetrical history. Sixty-six women living in a physically abusive relationship, and 114 women randomly selected and not presently living in such a relationship were interviewed. The women reported 312 completed pregnancies. Five of these were twin pregnancies and one was a stillbirth without information on birth weight. Of the 306 pregnancies included in the analysis, violence had occurred in 40. The mean birth weight of births reported by women exposed to violence during pregnancy was 229 g less than the equivalent figure in non-exposed pregnancies. Adjustment for education, primiparity, and history of addiction reduced the difference in mean birth weight to 175 g.

Maternal sickle cell trait is not a cause of low birthweight in Nigerian neonates

As a result of reports of reduced birthweight in neonates of mothers with hemoglobin AS (Hb-AS) in other populations, we compared birthweights in 57 Hb-AS primigravidas in Nigeria with 60 controls who were sickle negative. There was no statistically significant difference in mean birthweight or placental weight between the groups. This finding may be due to development of resistance against malaria infection by Hb-AS women in this population.

Twin gestations and prophylactic hospitalization

The study evaluates the benefit of elective hospitalization in preventing premature deliveries of twin gestations. Three groups of women with twin gestations, having no other complications of pregnancy which could cause premature delivery, were evaluated. The study group was comprised of 43 women who were electively hospitalized between 30—32 and 36 weeks of gestation. Control group 1 was comprised of 55 women who were not hospitalized but were instructed to rest at home. Control group 2 was comprised of 53 women who were not hospitalized and were not instructed to rest at home. Our results showed that elective hospitalization did not significantly affect the gestational duration or the prematurity rate. However the mean birthweight difference between the study group and the two control groups were 143 ± 83 g and 205 ± 84 g, respectively. This result was more significant in multiparous women. The slight increase in birthweight of the hospitalized women compared to the controls, does not seem to justify the cost of hospitalization.

Perinatal risk for infants of unmarried mothers, over a period of 20 years

The perinatal events of the infants of 444 unmarried mothers, 3.7% of the total Northern Finland birth cohort from 1966, were compared with those of infants of 11 525 married mothers (95.5%), and a similar comparison was made between 395 (4.2%) unmarried mothers and 7516 (80.3%) married mothers in a second Northern Finland birth cohort in 1985–1986. 1336 mothers, 14.3% of the mothers in this later cohort, were cohabiting. Divorced and widowed mothers were excluded from both cohorts. The infants of the unmarried mothers had a significantly lower mean birth weight, were more likely to be small for their gestational age (SGA), of low birth weight (LBW) (below 2500 g) and had a higher incidence of pre-term births than those of the married mothers in both cohorts. Perinatal mortality was significantly higher among the unmarried mothers only in the former cohort. These differences in perinatal events diminished markedly after adjustment for maternal age, parity, height, years of schooling and smoking habits, but did not totally disappear. The difference in the incidence of pre-term births diminished, but remained significant in both cohorts. The difference in mean birth weight, in the incidence of LBW infants and in perinatal mortality remained significantly less favourable to the unmarried mothers only in the 1966 cohort. It seems that the gap between the married and unmarried mothers had diminished. The incidence of SGA infants did not differ significantly between the married and unmarried mothers in either cohort after adjustment for the background variables. The cohabiting mothers formed an intermediate group between the married and single unmarried mothers in respect of perinatal events, but were close to the married mothers. In raw figures, the mean birth weight in this group was significantly lower and the incidence of SGA infants higher than among the married mothers, but these differences also disappeared after adjustment of the background variables.

Early Detection of Delayed Myelination in Preterm Infants

Myelination of the central nervous system can be demonstrated with magnetic resonance imaging. The influence of periventricular-intraventricular hemorrhage and periventricular leukomalacia on cerebral myelination was studied using magnetic resonance imaging. The subjects were 33 preterm infants of less than 30 weeks' gestation studied at 44 weeks' postmenstrual age: 11 infants with periventricular-intraventricular hemorrhage, 7 with periventricular leukomalacia, and 15 without periventricular-intraventricular hemorrhage or periventricular leukomalacia. There were no differences in mean gestational age and birth weight between the three groups. However, infants without periventricular-intraventricular hemorrhage or periventricular leukomalacia had significantly less respiratory distress syndrome. At 44 weeks postmenstrual age, infants with periventricular leukomalacia had a significantly delayed myelination pattern (stage M2) in comparison with infants without periventricular-intraventricular hemorrhage or periventricular leukomalacia and infants with periventricular-intraventricular hemorrhage (stages M3 and M4). The latter two groups had myelination stages that were similar to those of healthy term infants at 44 weeks' postmenstrual age. The results demonstrate that periventricular leukomalacia causes delayed myelination of the cerebrum, whereas periventricular-intraventricular hemorrhage does not.