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The relationship of birth weight and birth weight discordance to cerebral palsy or mental retardation later in life for twins weighing less than 2500 grams.

OBJECTIVE: This study tested the hypothesis that twins with a birth weight < 2500 gm who subsequently had cerebral palsy or mental retardation had a birth weight distribution or birth weight discordance distribution differing from that of the total live-born twin population also weighing < 2500 gm at birth. STUDY DESIGN: All twins born in Sweden between 1973 and 1980 (n = 5382) and having a birth weight < 2500 gm were identified by using information stored at the Medical Birth Registry, the National Board of Health and Welfare, Stockholm, or at Statistics Sweden. To identify twins with cerebral palsy or mental retardation, a questionnaire bearing the personal identification number (given to all newborns in Sweden shortly after birth) was distributed to all rehabilitation centers, all county school boards, all local boards of education, and to all County Councils for the Provisions and Services for the Mentally Retarded. The questionnaire was distributed in 1988 and 1989 when the twins were > or = 8 years old. RESULTS: Altogether 115 disabled twins resulting from 99 pregnancies were identified. The incidence of disabled twins per 1000 was 21.4 (95% confidence interval 17.5 to 25.2). No obvious difference was evident in the distribution of birth weight discordance when the twins with disability were compared with the population of all live-born twins having a birth weight < 2500 gm. Disabled twins had a significantly lower birth weight for gestational age (t = -3.5, p < 0.001), but in fact only 10 (8.7%) twins had a birth weight < -2 SD. No difference in the incidence of disability was found for twin A versus twin B (relative risk 1.3, 95% confidence interval 0.8 to 1.9) or for like-sex versus unlike-sex twins (relative risk 1.0, 95% confidence interval 0.6 to 1.6). However, the larger twin in the pair had a significantly higher incidence of cerebral palsy than the smaller one did (relative risk 2.6, 95% confidence interval 1.4 to 4.8). CONCLUSIONS: Birth weight discordance for twins seems not to be related to disability later in life. The great majority of twins with a birth weight < 2500 gm who later became disabled were appropriate for gestational age at birth.

Birth Weight↗

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↗

Low birth weight,very low birth weight rates and gestational age-specific birth weight distribution of korean newborn infants.

To obtain the low birth weight (LBW) rate, the very low birth weight (VLBW) rate, and gestational age (GA)-specific birth weight distribution based on a large population in Korea, we collected and analyzed the birth data of 108,486 live births with GA greater than 23 weeks for 1 yr from 1 January to 31 December 2001, from 75 hospitals and clinics located in Korea. These data included birth weight, GA, gender of the infants, delivery type, maternal age, and the presence of multiple pregnancy. The mean birth weight and GA of a crude population are 3,188 +/-518 g and 38.7+/-2.1 weeks, respectively. The LBW and the VLBW rates are 7.2% and 1.4%, respectively. The preterm birth rate (less than 37 completed weeks of gestation) is 8.4% and the very preterm birth rate (less than 32 completed weeks of gestation) is 0.7%. The mean birth weights for female infants, multiple births, and births delivered by cesarean section were lower than those for male, singletons, and births delivered vaginally. The risk of delivering LBW or VLBW infant was higher for the teenagers and the older women (aged 35 yr and more). We have also obtained the percentile distribution of GA-specific birth weight in infants over 23 weeks of gestation.

Birth Weight↗

Estrogen and alpha-fetoprotein levels in maternal and umbilical cord blood samples in relation to birth weight.

Birth weight has been associated with a subsequent risk of breast cancer. The present study examined associations between birth weight and pregnancy estrogens and alpha-fetoprotein (AFP). The concentrations of estradiol, estriol, and AFP were measured in maternal and umbilical cord blood samples from 194 women during pregnancy and at birth. Birth weight was significantly positively correlated with maternal serum estradiol and estriol levels in the 29th week (estradiol: r = 0.16, P = 0.03; estriol: r = 0.29, P = 0.001) and at delivery (estradiol: r = 0.20, P = 0.01; estriol: r = 0.41, P < 0.0001) after controlling for covariates. The umbilical cord estriol level was moderately but significantly correlated with birth weight (r = 0.15, P = 0.049). There was no significant association between umbilical cord serum estradiol and birth weight. There was no significant association between birth weight and maternal serum AFP in any gestational week. Umbilical cord AFP was significantly inversely correlated with birth weight (r = -0.16, P = 0.04). Umbilical cord AFP was unrelated to cord levels of estradiol and estriol. The data suggested a greater exposure to estriol and a lower exposure to AFP among high birth weight babies.

Adolescent↗

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↗

Recent trends in infant mortality rates and proportions of low-birth-weight live births in Canada.

OBJECTIVE: To identify spatial patterns of changes in infant mortality rates and proportions of low-birth-weight live births observed in 1994. SETTING: Canada. SUBJECTS: Live births and infant deaths in Canada between 1987 and 1994. Data for Newfoundland were unavailable for 1987 through 1990. OUTCOME MEASURES: Annual infant mortality rates (crude and after excluding live newborns weighing less than 500 g); proportion of live births by low-birth-weight category (500-2499 g). RESULTS: Nova Scotia, New Brunswick, Quebec and Manitoba had lower crude and adjusted infant mortality rates in 1994 than in 1993. Newfoundland, Saskatchewan, Alberta and British Columbia had higher rates in 1994 than in 1993. The crude rate in Ontario was lower, and the adjusted rate higher, in 1994 than in 1993. A downward trend in the proportion of low-birth-weight live births was observed in Quebec (chi(2) for trend = 29.2, p < 0.01). Conversely, an upward trend was observed in Ontario (chi(2) for trend = 241.3, p < 0.01). However, the increase may have been due to data errors, especially in 1993 and 1994, involving truncation of ounces in 2 digits to 1 digit (e.g., 5 pounds 10 ounces became 5 pounds 1 ounce). CONCLUSIONS: Although the marginal increases in infant mortality observed in several provinces could be the result of random variation, future trends should be closely monitored. The proportion of low-birth-weight live births in Canada (excluding Ontario) appears to be stable, with Quebec showing significant reductions. The errors in data for Ontario need to be corrected before trends can be estimated for that province and for Canada as a whole.

Birth Weight↗

Improved outcome for very low birth weight multiple births.

This study describes time trends for very low birth weight multiple births in relation to very low birth weight singletons. Two cohorts of very low birth weight (less than 1250 gm) children recruited between 1983-85 (cohort 1, n = 115) and 1992-94 (cohort 2, n = 144) were compared. The Bayley Scales of Infant Development and a standardized neurologic examination were administered at 2 years corrected age. Neurodevelopmental outcome did not change between cohort 1 and 2 for singletons. For multiple births, mean Mental Developmental Index increased after adjustment for neonatal risk factors [adjusted mean (standard deviation) 81.8 (11.7) to 96.5 (18.6), analysis of covariance P = 0.007]. The prevalence of cerebral palsy decreased, however not significantly [adjusted odds ratio (95% confidence interval) 0.3 (0.1-1.5), P = 0.14]. The proportion of disease-free survival (no cerebral palsy and no developmental delay) increased for multiple births (7-37%, P = 0.002), but not for singletons. In cohort 2, neurodevelopmental outcome of multiple births was similar to that of singletons. The cognitive outcome of very low birth weight multiple births improved, possibly because of changes in perinatal practice. However, neurodevelopmental outcome was similar to that of very low birth weight singletons who were unaffected by changes in neonatal care with high proportions of motor delay and cerebral palsy.

Case-Control Studies↗

[Relationship between maternal anthropometry and weight gain with birth weight, and risks of low birth weight, small for gestational age and prematurity at an urban population of Buenos Aires, Argentina].

To asses the relationship between body mass index and net weight gain during pregnancy with birth weight and the risks of low birth weight, small for date and prematurity 9613 records from Sardá's Perinatal Database between 1994-1995 were reviewed. Exclusion criteria were fetal death, twin pregnancy, congenital malformations, lack of prenatal visits and lack of preconceptional weight and height. 9.6% of mothers and 15% of adolescents presented with low preconceptional BMI (median: 24.8 +/- 4.3 kg/m2); in contrast, 28% were overweight and obese. Net weight gain (median 9.25 +/- 4.9 kg) accounted for 16% of previous weight and was higher with lower BMI (p = 0.001). Birth weight (median 3375 +/- 467 g) decreased with lower BMI (p = 0.001) and the risks of low birth weight (p < 0.05), small for date (p < 0.05), and prematurity (p = 0.05) was independently associated with BMI, and increased (p < 0.001) when lower the net weight gain was. The best predictors for low birth weight, small for date and prematurity risks were low preconceptional weight (40-51 kg) (adjusted OR 1.72; [95%CI 1.48-1.95], 2.12 [1.82-2.41] and 1.46 [1.12-1.79] respectively). Net weight gain and several predictive variables did not explain more than 10.8% of the variability of birth weight. Preconceptional weight should have important implications for the design of future nutritional strategies at a poblational level, especially for adolescents.

Adolescent↗

Maternal pre-pregnancy weight and placental weight determine birth weight in normal Jamaican infants.

Birth weight is related to neonatal health and long-term risk of chronic disease. Since animal studies have shown that birth outcome is related to placental function, the present project was designed to explore the relationship between birth weight and placental growth and composition with maternal factors during pregnancy among normal term pregnancies in 51 primiparous and 40 multiparous women delivering at the University Hospital of the West Indies. Both groups were followed from 15 weeks of gestation to term. The primiparous group was generally younger than the multiparous (mean age 22 +/- 4 versus 31 +/- 5 yr). They were significantly lighter (55 +/- 8 versus 61 +/- 9 kg) with a lower body mass index (21 +/- 3 versus 23 +/- 4 kg/m2) during early pregnancy, but gained more weight during pregnancy, 11 kg compared with 8 kg, respectively. The duration of pregnancy was similar for both groups. Although the size of the placenta was not significantly different between the two groups, the mean weight of the multiparous placentae was more than that of the primiparous placentae. Also, for all mothers both placental weight and initial maternal weight related directly to birth weight. Placental non collagen protein (NCP), sodium and potassium contents were significantly higher for multiparous women and were related to birth weight. The primiparous group had babies who were significantly lighter, 3.03 kg compared with 3.36 kg, for the multiparous and this could be attributed to differences in placental function and maternal weight. When account was taken of the difference in maternal weight at the start of pregnancy and the difference in placental weight, parity no longer explained any of the differences in birth weight. It is concluded that maternal body weight at the time of becoming pregnant and the early development of the placenta determine the efficiency with which nutrients might be delivered to the foetus and hence foetal growth. The difference in birth weight between primiparous and multiparous women can be explained by the differences in maternal weight at the time of becoming pregnant.

Adult↗

Different weight gain in women of normal weight before pregnancy: postpartum weight and birth weight.

OBJECTIVE: To identify the effect of different gestational weight gains among women of normal weight before pregnancy on babies' birth weights, and women's weights 18-24 months postpartum. METHODS: Two groups of women of normal weight before pregnancy (body mass index [BMI] 19.6-25.4 kg/m2) took part in the study (n = 200). They gained either moderate weight (9-15 kg) or high weight (18-24 kg) during pregnancy. From maternity records and telephone interviews, information on age, height, prepregnancy and postpartum weight, gestational weight gain, babies' birth weights, lactation, parity, and smoking habits was collected. RESULTS: High maternal weight gain during pregnancy resulted in mean birth weight 286 g higher than that of babies of mothers who gained moderate weight. The correlation coefficient between birth weight and gestational weight gain was 0.3 (P < .001). The postpartum weight of women with high weight gain during pregnancy was 2.6+/-0.38 kg (mean +/- standard error of the mean [SEM]) more than before pregnancy but the group of moderate weight gain weighed 0.1+/-0.47 kg less than before pregnancy (P < .001). However, most women in both groups (88.6%) regained normal weight, and prepregnant weight correlated strongly with the weight 18-24 months postpartum (r = 0.79, P < .001). There was not a significant correlation between the duration of lactation and postpartum weight loss (r = 0.04, P > .05). CONCLUSION: High gestational weight gain among women of normal weight before pregnancy increases birth weight and women's weight postpartum, compared with moderate weight gain. Prepregnant weight is more indicative of postpartum weight, and women reach normal weight again irrespective of gestational weight gain.

Adult↗

Independent effect of maternal birth weight on infant birth weight.

The relationship between the birth weights of the mother and her infant was evaluated in a sample of 106 women consecutively delivered of a single live birth. Women were included in the study if their birth weight was available in hospital files or from another reliable source. Women that were themselves a twin or had diseases complicated the course of the pregnancy were excluded. A positive significant correlation was found between mother and infant birth weights (r = 0.29, p = 0.003). This correlation remained significant (partial r = 0.22, p = 0.039) after adjusting for other covariables such as the mother's age, height, education, whether the pregnancy was planned, number of cigarettes smoked daily during pregnancy, month of first antenatal visit and number of visits, weight at end-pregnancy, gestational age and sex of the newborn. In the multiple linear regression model, mother's birth weight explained 3% of the variation observed in infant birth-weight. A weaker crude correlation was also found between mothers' birth weight and gestational age (r = 0.19, p = 0.06). This study shows that maternal birth weight is an independent predictor of infant birth weight, and confirms previous findings suggesting that this maternal factor has a stronger effect on the birth weight than on the gestational age of the newborn.

Birth Weight↗

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↗

Assessing survey measures of infant birth weight and birth size in Ecuador.

The purpose of this study was to assess the utility of using maternal assessments of infant birth size as proxy measures for birth weight in Ecuador, a country in which a sizeable proportion of births take place at home, where birth weight is typically not recorded. Four thousand and seventy-eight women who experienced a live singleton birth between January 1992 and August 1994 were interviewed in the Ecuador Demographic and Maternal-Child Health Survey. All women were asked if their child was weighed at birth, his/her weight, and what they considered to be his/her birth size relative to other newborns. The consistency between birth size and birth weight measures was assessed, and the differences between infants with and without reported birth weights were explored. The authors conclude that maternal assessments of birth size are poor proxy indicators of birth weight. Estimates of low birth weight based on maternal assessments of birth size as very small should be recognized as underestimates of the actual prevalence of low birth weight. Moreover, infants for whom birth weights are missing should not be considered similar to those for whom weight was reported. Those without reported birth weights are more likely to be low birth weight. Thus, relying solely on reports of numeric birth weight will underestimate the prevalence of low birth weight.

Adult↗

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↗