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Causes of low birth weight births in public and private patients.

This examination of the cause of low birth weight births in two model populations, one of public and one of private patients, finds significant differences in the reasons for low birth weight births in the two groups. Idiopathic premature labor was related to 47.1% of private low birth weight births, but only 24.8% of public births; low birth weight term (26.7%) and premature rupture of fetal membranes (33.7%) were more common in public low birth weight births than in private births (13.8% and 23.0%, respectively). Medical problems were related to 16.1% of private and 14.9% of public low birth weight births. Since current prematurity prevention methods are most likely to prevent low birth weight births related to idiopathic premature labor, the relative success of such programs in reducing the rate of low birth weight births is likely to depend on the characteristics of the patient population to which the programs are directed.

Ethnicity

Breed effects and heterosis in advanced generations of composite populations for birth weight, birth date, dystocia, and survival as traits of dam in beef cattle.

Heterosis effects were evaluated as traits of the dam in F2 progeny of F1 dams and F3 and 4 progeny of F2 and 3 dams in three composite populations of beef cattle. Traits included birth weight, birth date, calving difficulty percentage, and survival percentage at birth, 72 h, and weaning for calves with dams of different age classes. Breed effects were evaluated for the nine parental breeds (Red Poll [R], Hereford [H], Angus [A], Limousin [L], Braunvieh [B], Pinzgauer [P], Gelbvieh [G], Simmental [S], and Charolais [C]) that contributed to the three composite populations (MARC I = 1/4 C, 1/4 B, 1/4 L, 1/4 H, 1/8 A; MARC II = 1/4 G, 1/4 S, 1/4 H, 1/4 A; and MARC III = 1/4 R, 1/4 P, 1/4 H, 1/4 A). Among calves with 2-yr-old dams, breed effects were significant for birth weight, birth date, calving difficulty percentage, and survival percentage at birth but not at 72 h and weaning. Calf survival at weaning was lowest for smallest (less than mu - 1.5 sigma) and largest (greater than mu + 1.5 sigma) birth weight classes and did not differ among intermediate birth weight classes. Calves with difficult births with 2-yr-old dams were significantly heavier at birth (39.6 vs 35.4 kg) and had significantly lower survival at 72 h (87.1 vs 92.2%) and at weaning (77.4 vs 85.1%) than calves with 2-yr-old dams that did not experience difficult births. Among calves with dams greater than or equal to 3 yr old and from dams of all ages, breed group effects generally were significant for the traits analyzed. Important breed group effects on dystocia and survival traits were observed independent of breed group effects on birth weight. Effects of heterosis were significant for birth weight for each generation of each composite population and for the mean of the three composite populations. Generally, heterosis effects for calving difficulty percentage were not significant. Effects of heterosis generally were significant for date of birth (earlier) for each composite population and for the mean of the three composite populations. Heterosis effects on survival to weaning percentage generally were positive but generally were not significant. Heterosis retained for birth weight, birth date, and survival percentage in combined F3 and 4 generation progeny of combined F2 and 3 generation dams did not differ (P greater than .05) from expectation based on retained heterozygosity. These results support the hypothesis that heterosis in cattle for these traits is the result of dominance effects of genes.

Analysis of Variance

The influence of previous low birth weight on birth weight, gestational age, and anthropometric measurements in the current pregnancy.

The effect of a previous low birth weight birth (less than 2750 g) was examined using a series of regression analyses. Effects on birth weight were partitioned into those associated with preterm delivery (128 g) and term delivery (178 g). Among term births, a mean difference of 107 g was associated with a previous birth of less than 2750 g, even after controlling for other risk factors including smoking, drug and alcohol use, maternal race, size, and hypertension. The pattern of measurements seen after a previous birth of less than 2750 g included significantly smaller head, chest, abdomen, arm, and thigh circumferences, but an insignificant impact on skinfold thicknesses and no significant effect on length measurements.

Anthropometry

Smoking in pregnancy: the influence on percentile birth weight, mean birth weight, placental weight, menstrual age, perinatal mortality and maternal diastolic blood pressure.

Smoking habits of 597 pregnant women were investigated; 48.6% of the women smoked during pregnancy. Percentile birth weight proved to be decreased compared with the Amsterdam birth weight charts. This decrease could be attributed largely to smoking in pregnancy. Mean birth weight was significantly lower in smokers than in nonsmokers (230 g; p less than 0.01). Placental weight and menstrual age were not affected by smoking during pregnancy. A statistically significant higher incidence of hypertension in pregnancy in the nonsmokers group compared with the smokers group (p less than 0.05) was established.

Adult

Effect of maternal and infant covariates on sibship correlation in birth weight.

Birth weight on 12,644 singleton infants from 6,196 sibships born in Maryland between 1980 and 1984 were used to estimate the effects of nine maternal and infant covariates on the sibship correlation in birth weight. Assuming a homogeneous correlation across all families, the estimated intraclass correlation was 0.4664 (+/- 0.0099). This high sibship correlation makes it possible to predict, with reasonable accuracy, the birth weight of a child given information on previous sibs, as well as covariates on the mother and/or infant pertinent to a given pregnancy. The reduction in variance associated with incorporating information on the nine covariates used here was approximately equal to that obtained by conditioning on a single previous sib. Testing for heterogeneity in correlation among different groups of families showed that a crude measure of parity (first live birth vs. other), time between births, mother's marital status, and maternal age at the birth of the last child significantly influenced the sibship correlation in birth weight.

Adult

Birth weight and birth defects in relation to maternal spermicide use.

The possible effects of maternal spermicide use on birth characteristics of offspring were examined in two studies. First, birth weight of offspring was examined in a cohort study of 302 women who reported using spermicides and 716 women who used no contraceptive methods in the year prior to pregnancy resulting in a 1974 live birth (without a malformation) in Upstate New York. There was no evidence that spermicide use prior to the last menstrual period (LMP) had an effect on mean birth weight or on the proportion of lower weights. Mean birth weight of female births was significantly lower in post-LMP spermicide users than in pre-LMP-only spermicide users and no-contraceptive users. In multiple linear regression analyses of birth weight among births to spermicide users, including maternal smoking during pregnancy and other variables, time of discontinuation of spermicide use was an important predictor of female (but not male) birth weight. In the second (case-control) study of 715 Upstate New York births with selected birth defects and 715 control births (matched on maternal age and race), no significantly increased relative risks were associated with maternal spermicide use prior to LMP or after LMP. Based on small numbers, relative risks for post-LMP spermicide use were greater than 1.00 for hypospadias (8/2 or 4.00, not significant) and for limb reduction defects (6/3 or 2.00, not significant).

Abnormalities, Drug-Induced

A comparison of the childhood health status of normal birth weight and low birth weight infants.

We analyzed previously unavailable data to describe the national health status in 1981 of noninstitutionalized children who were low birth weight infants. They were compared with normal birth weight children. All data contained in the analysis were based on weighted national estimates. Low birth weight children in general were found to have more chronic conditions, more hospitalizations, more days in bed because of illness, more limitations of activity, poorer health status as perceived by parents, and more school days lost because of illness. However, numbers of physician visits were not different even for low birth weight children younger than 2 years, which is inconsistent with the higher proportions of multiple hospitalizations, chronic conditions, and other illness measures. The proportions of children in the younger age groups at risk for health problems associated with low birth weight should be increasing. The proportion of very low birth weight children in the younger age groups with higher excessive morbidity measures tends to support the possibility. The increased survival of high-risk infants raises concern about their future requirements for special medical and educational services, and about the resulting stress on their families. Normal birth weight children were found to make a major contribution to the prevalence of morbidity. It is not the children identified as at risk as a result of low birth weight that comprise most of those with illnesses. The physical, social, and psychological environment after birth probably has the largest impact on the health status of our children. The attributable risk of excessive morbidity associated with low birth weight and very low birth weight reinforces the concept that while the overall impact is not large, the consistent pattern of poorer health for children born with low birth weight, compared to those of normal birth weight, shown in this analysis, is striking. The pattern reinforces concerns with the many factors associated with low birth weight and their effects on the present and future health of the population.

Birth Weight

The effect of maternal height on birth weight and birth length.

This retrospective study examined the gestational age at which differences were observed between birth weights and birth lengths of infants whose mothers differed by height. Infants whose gestational ages were between 24 and 42 weeks born to women 59-62 inches (150-157 cm) tall were compared to similar infants born to women 66-69 inches (168-175 cm) tall. Significant differences occurred in birth weight and birth length from 35 weeks onward. The infants of the shorter women were symmetrically smaller than the infants of the taller women as the infant ponderal indexes did not differ.

Birth Weight

Relative effect of parental birth weight on infant birth weight at term.

The relations between some hereditary and environmental factors and the variation in infant birth weight were estimated by multiple linear regression analyses on a sample of 276 Scandinavian single term pregnancies. Gestational age explained 10.9%, fetal factors (maternal and paternal birth weights and fetal sex) 7.9%, maternal factors (parity, pre-pregnancy weight and height) 5.5% and external factors (adjusted weight gain and smoking) 5.8% of the variation in infant birth weight. It is concluded that maternal and paternal birth weights are rather poor predictors of infant birth weight. Together they explain only 5.6% of the variation in infant birth weight at term.

Analysis of Variance

[Seasonal variation of mean birth weight and births in Nagano Prefecture].

Seasonal variation of mean birth weight in Nagano Prefecture was examined by a traditional time series analysis, which decomposes the variation in a series into trend, seasonal variation, other cyclic changes, and remaining irregular fluctuations, based on the data in Vital Statistics from January 1974 to December 1983. The seasonal index of mean birth weight showed a unimodal pattern with a peak in June for males, and a bimodal pattern with peaks in spring and autumn in females with statistical significance. Previous reports have revealed that gestational period is the most important factor associated with birth weight. Therefore, we carried out time series analysis for the mean gestational period and observed an apparent seasonal periodicity, which showed a unimodal pattern with a bottom in winter for both sexes and parities. According to the results of statistical testing of the degree of coincidence between two time series, the time series of mean birth weight and that of mean gestational periods showed statistically significant coincidences in their monthly variations for multiparae. On the other hand, mean birth weight at 40 gestational weeks, which reflects the intrauterine growth, did not show seasonality. These results suggest that seasonality in gestational periods might play an important role in creating seasonal variations of mean birth weight in Nagano Prefecture. The average daily number of births by month also showed apparent seasonalities both for primiparae and multiparae. Primiparae showed a bimodal pattern with peaks in February and August, while multiparae showed a unimodal pattern with a peak in May and a bottom in November. It has been said that the seasonality in marriage is one of important factors associated with seasonal variation in births.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Rate

Postural development in very low birth weight and normal birth weight infants.

In this study the seven postural responses selected by Vojta to evaluate neuromotor development were applied to 68 very low birth weight (VLBW) (greater than 1500 g) infants and to 28 healthy infants of normal birth weight (less than 2500 g). Of the 68 VLBW infants, 41 were small for gestational age and 27 appropriate for gestational age. All infants were examined between 37 and 40 weeks postmenstrual age. They were all later assessed on the Griffiths Mental Developmental Scale at 12 and 18 months. There were significant differences in postural reactions between the two groups which confirmed the lower tone and greater extension previously described in very low birth weight infants. An important finding in the study was that poor head and trunk righting noted at four months corrected age in very low birth weight infants, was associated with less developed locomotion at 12 and 18 months as assessed by the Griffiths Mental Developmental Scale. Thus, a delay in maturation in very low birth weight infants which was apparent from the assessment of postural responses in early infancy was still identifiable on the locomotor subscales at 12 and 18 months. Five of Vojta's responses were shown to be useful as part of the neurological assessment of high risk infants.

Apgar Score

[Normal standards for birth weight and birth length of newborns in the DDR].

Normal anthropometric standards of birth weight and birth length are presented for newborn boys and girls in the GDR between 28 and 44 weeks' gestational age. Newborns with uncertain duration of gestation, multiple births, malformations and stillbirths have been excluded. It is directed to necessity of regional standards.

Anthropology, Physical