Low Birth Weight Odds Ratio Research Articles

Job control, substantive complexity, and risk for low birth weight and preterm delivery: An analysis from a state birth registry

Indices of job strain have demonstrated a variable relationship to low birth weight (LBW) and prematurity, with conflicting study results. This study sought to examine the associations of psychosocial work environment characteristics with adverse pregnancy outcomes using and comparing the demand-control model and job attributes derived from the O*NET. Job characteristics were imputed to maternal occupation recorded in the 2000 Connecticut state birth registry for 26,408 singleton births, using scores for psychological job demands, control, and physical demands derived from the Job Content Questionnaire, and for substantive complexity of work and physical demands using variables derived from O*NET job attributes. Odds ratios for LBW and preterm delivery were estimated while controlling for relevant covariates. High psychological demands were not associated with pregnancy outcomes, while high physical demand scores from the O*NET were associated with LBW. Associations of term- and all-LBW with both low control and low substantive complexity were attenuated by adjustment for educational and demographic covariates. A gradient with lower scores was seen for term LBW and substantive complexity, and for prematurity and control. Both constructs were correlated with maternal education. These results suggest that low maternal job control and substantive complexity may be modestly associated with LBW and, to a lesser extent, prematurity. A greater association with control may explain why a weak link of birth outcomes to high-strain work has been noted in past studies. Observed associations with occupational are reduced after adjustment for relevant confounding variables, in particular educational level and race/ethnicity.

Exposure to organic solvents and adverse pregnancy outcomes

Organic solvents are among the most common exposures in the workplace. Our objective was to elaborate the relationship between prenatal occupational solvent exposure and fetal growth as well as duration of pregnancy, and to quantify the impact of occupational organic solvent exposure. We conducted a population-based study of 1670 singleton newborns of women who participated in The Finnish Prenatal Environment and Health Study after their delivery (response rate 94%) and who were working during pregnancy (65%). Exposure information was based on questions about exposure to solvents at work before and during pregnancy. The health outcomes, based on information from a questionnaire and the Finnish Medical Birth Registry, were low birth weight (<3000 g), small-for-gestational-age and preterm delivery (<37 weeks). In logistic regression analysis, the risk of the baby being small-for-gestational-age was related to any exposure to solvents 3 months before or during pregnancy with an adjusted odds ratio (OR) of 1.67 [95% confidence interval (CI) = 1.02-2.73]. Also the adjusted OR for low birth weight was elevated with exposure, although it did not reach statistical significance (1.17; 95% CI = 0.71-1.93). The population attributable fraction for small-for-gestational-age was 2.3% for all pregnant women. Work exposure to organic solvents may reduce intrauterine growth by increasing the risk of the baby being small-for-gestational-age.

Self-reported experiences of racial discrimination and Black-White differences in preterm and low-birthweight deliveries: the CARDIA Study.

We examined the effects of self-reported experiences of racial discrimination on Black-White differences in preterm (less than 37 weeks gestation) and low-birthweight (less than 2500 g) deliveries. Using logistic regression models, we analyzed data on 352 births among women enrolled in the Coronary Artery Risk Development in Young Adults Study. Among Black women, 50% of those with preterm deliveries and 61% of those with low-birthweight infants reported having experienced racial discrimination in at least 3 situations; among White women, the corresponding percentages were 5% and 0%. The unadjusted odds ratio for preterm delivery among Black versus White women was 2.54 (95% confidence interval [CI]=1.33, 4.85), but this value decreased to 1.88 (95% CI=0.85, 4.12) after adjustment for experiences of racial discrimination and to 1.11 (95% CI=0.51, 2.41) after additional adjustment for alcohol and tobacco use, depression, education, and income. The corresponding odds ratios for low birthweight were 4.24 (95% CI=1.31, 13.67), 2.11 (95% CI=0.75, 5.93), and 2.43 (95% CI=0.79, 7.42). Self-reported experiences of racial discrimination were associated with preterm and low-birthweight deliveries, and such experiences may contribute to Black-White disparities in perinatal outcomes.

Association of a woman's own birth weight with subsequent risk for gestational diabetes.

Several studies have reported links between reduced fetal growth and subsequent risk for type 2 diabetes among older adults, but the association between indices of fetal growth and gestational diabetes mellitus (GDM), a major complication of pregnancy and a strong predictor of type 2 diabetes, remains little explored. To test the hypothesis that a woman's own fetal growth is inversely related to her later risk for GDM. Case-control study of linked hospital discharge and vital record data from the New York State Department of Health. Healthy women who completed their first pregnancies in New York State between 1994 and 1998 and who were also born in New York State. Records from each woman's first pregnancy were linked to those from her own birth (1970-1985). Cases were 440 women with a record of GDM. Controls were 22 955 remaining women with no indication of GDM. A woman's own birth weight, alone and adjusted for gestational age. Birth weight showed a U-shaped relationship to a woman's risk of GDM in her first pregnancy, with the highest risks associated with low and high birth weights. Odds ratios (ORs) adjusted for gestational age were 2.16 (95% confidence interval [CI], 1.04-4.50) for birth weight of less than 2000 g and 1.53 (95% CI, 1.03-2.27) for a birth weight of 4000 g or more. Adjustment for potential confounding factors, particularly prepregnancy body mass index and maternal diabetes, increased the OR for low birth weight to 4.23 (95% CI, 1.55-11.51), but reduced the OR for high birth weight to 0.92 (95% CI, 0.54-1.57), leaving a strong inverse dose-response relationship between birth weight and risk of GDM (adjusted P for trend <.001). In this large population-based study, a woman's own birth weight was strongly and inversely related to her risk of GDM, suggesting that early life factors may be important in the etiology of this disorder.

Outdoor Air Pollution, Low Birth Weight, and Prematurity

Thisstudy tested thehypothesis, suggested byseveral recent reports, that airpollution may increase therisk ofadverse birth outcomes. Thisstudy analyzed all singleton live births registered bytheCzech national birth register in1991in67districts where atleast onepollutant wasmonitored in1990-1991 (n= 108,173). Maternal exposures tosulfur dioxide (S02), total suspended particles (TSP), andnitrous oxides (NO.) ineach trimester ofpregnancy wereestimated asthe arithmetic meansofall daily measurements taken byall monitors inthedistrict ofbirth ofeach infant. Oddsratios oflowbirth weight (<2,500 g),prematurity (<37weeks ofgestation), and intrauterine growth retardation (IUGR; <10th percentile ofbirth weight forgestational ageand sex) wereestimated byrobust logistic regression. Themedian (and 25thand75thpercentile) trimester exposures were32(18, 56)pg/m3 for S02;72(55, 87)pg/m3 forTSP;and38(23, 59) pg/m3 forNOx. Lowbirth weight (prevalence 5.2%) andprematurity (prevalence 4.8%) were associated withS02andsomewhat less strongly withTSP.IUGRwasnotassociated withany pollutant. Theeffects onlowbirth weight andprematurity weremarginally stronger forexposures inthefirst trimester, andwerenotattenuated atall byadjustment forsocioeconomic factors orthemonth ofbirth. Adjusted odds ratios oflowbirth weight were1.20 [95%confidence interval(CI), 1.11-1.30] and1.15 (CI, 1.07-1.24) fora50pg/m3 increase inSO2andTSP,respectively, inthefirst trimester; adjusted oddsratios ofprematurity were1.27 (CI, 1.16-1.39) and 1.18 (CI, 1.05-1.31) for a50pg/m3 increase inSO2andTSP,respectively, inthefirst trimester. Lowgestational ageaccounted for theassociation between SO2andlowbirth weight. These findings provide further support forthehypothesis that airpollution canaffect theoutcome ofpregnancy. Keywords airpollution, birth, epidemiology, lowbirth weight, pregnancy, premature birth. Environ Health Perspect 108:173-176 (2000). [Online 10January 2000] http://ehpnetl.n ie/hs.nih.gov/docs/2000/108p173-176bobak/abstract.html

Sources of prenatal care data and their association with birth outcomes of HIV-infected women.

Different sources of prenatal care data were used to examine the association between birth outcomes of HIV-infected women and the Adequacy of Prenatal Care Utilization (APNCU) index. Adjusted odds ratios of birth outcomes for 1858 HIV-positive mothers were calculated for APNCU indexes on the basis of birth certificate data or 3 types of physician visits on Medicaid claims. Claims- and birth certificate-based APNCU indexes agreed poorly (kappa < 0.3). Only the broadest claims-based APNCU index had lower adjusted odds ratios for low birthweight (0.64; 95% confidence interval [CI] = 0.49, 0.84) and preterm birth (0.70; 95% CI = 0.54, 0.91). The birth certificate-based index had a reduced adjusted odds ratio (0.73; 95% CI = 0.56, 0.95) only for preterm birth. The association of birth outcomes and adequacy of prenatal care in this HIV-infected cohort differed significantly depending on the source of prenatal care data.

Risk factors for neonatal mortality: Harare Central Hospital Neonatal Unit

To assess risk factors for neonatal mortality in a tertiary level neonatal unit. Case control analysis of routine neonatal data for 1998. Harare Central Hospital Neonatal Unit. All neonates delivered at Harare Maternity Hospital and admitted to the neonatal unit for care between January and December 1998. Neonatal mortality in hospital. A total of 5,305 neonatal admissions were studied of which 19.3% died in hospital. The median age at death was two days (Q1 = 1, Q3 = 3) and the median age at hospital discharge was 3 days (Q1 = 1, Q3 = 6). Risk factors for mortality were un-booked mother odds ratio (OR) 2.36 (95% CI = 1.98 to 2.81), breech delivery OR: 1.76 (95% CI = 1.39 to 2.22), low birth weight OR: 4.67 (95% CI = 3.92 to 5.57), prematurity OR: 2.36 (95% CI = 2.09 to 2.66), congenital malformations OR: 2.80 (95% CI = 1.72 to 4.53) and birth asphyxia OR: 1.79 (95% CI = 1.51-2.12). Being admitted for respiratory distress was associated with better survival OR: 0.22 (95% CI = 0.17 to 0.28). Having a Caesarian section was also protective OR: 0.60 (95% CI = 0.47 to 0.76). Mother's age, parity, time of delivery and sex were not significantly associated with mortality odds ratios (95% CI) of 1.07 (0.86 to 1.34), 0.94 (0.78 to 1.13), 1.10 (0.93 to 1.30) and 0.89 (0.78 to 1.03) respectively. On regression analysis birth weight greater than 2,500 g, being un booked and breech delivery were predictive of mortality with OR (95% CI) of 0.99 (0.99 to 0.99), 1.31 (1.12 to 1.61) and 1.15 (1.04 to 1.28) respectively. Low birth weight is the highest risk factor for mortality in this tertiary level hospital. Strategies targeted at low birth weight infants such as antenatal corticosteroid use, improved intrapartum care, appropriate antibiotic use, improved efficiency and access to neonatal intensive care will have the most impact on neonatal mortality.

An evaluation of the effects of intermittent sulfadoxine—pyrimethamine treatment in pregnancy on parasite clearance and risk of low birthweight in rural Malawi

The prevalence of infection with malarial parasites and the incidence of anaemia and delivery of infants with low birthweight (LBW) were investigated in 575 Malawian mothers who received one, two or three doses of sulfadoxine-pyrimethamine (SP) during pregnancy. All the subjects were enrolled at their first antenatal visit and all delivered at hospital. The prevalence of Plasmodium falciparum infection at first antenatal visit was 35.3% in primigravidae and 13.6% in multigravidae (P < 0.001). Mean haemoglobin concentration was significantly lower in primigravidae than in multigravidae (8.8 v. 9.5 g/dl; P< 0.001). Of the 233 women tested for HIV infection, 18.8% of the primigravidae and 23.7% of the multigravidae were seropositive.At delivery, there was no significant difference in parasite prevalence in peripheral or placental blood between women who had received one or two antenatal doses of SP. The multigravidae who had received two doses of SP had higher mean haemoglobin concentrations than those who had received just one (P = 0.009) [this difference was not seen in the primigravidae (P = 0.92)]. However, linear regression analysis indicated that the haematinic supplements given to the subjects contributed more to this increase in haemoglobin concentration than the SP.The mean birthweights were higher, and incidence of LBW lower in babies born to primi- and multi-gravidae who had received two or three doses of SP treatment than those seen in babies born to women who had had just one dose (P < 0.03 for each). The odds ratio for LBW in primigravidae compared with multigravidae decreased from 3.2 to 1.0 as the number of SP doses increased from one to three. The benefit of three doses (compared with none) was equivalent to the population-attributable risk of LBW in primigravidae being reduced from 34.6% to 0%. Subjects who were seropositive for HIV were twice as likely to give birth to LBW babies as the other subjects.The use of SP was not associated with maternal side-effects or perinatal complications. The present results indicate that multiple doses of SP taken during pregnancy will lead to a highly significant reduction in the incidence of LBW in infants born to primigravidae, even if the women have HIV infections. This reduction is observable even when parasite prevalence at delivery is high because of re-infections in late pregnancy; reduction in parasite prevalence earlier in pregnancy, as the result of SP treatment, leads to improved foetal growth.

An evaluation of the effects of intermittent sulfadoxine-pyrimethamine treatment in pregnancy on parasite clearance and risk of low birthweight in rural Malawi.

The prevalence of infection with malarial parasites and the incidence of anaemia and delivery of infants with low birthweight (LBW) were investigated in 575 Malawian mothers who received one, two or three doses of sulfadoxine-pyrimethamine (SP) during pregnancy. All the subjects were enrolled at their first antenatal visit and all delivered at hospital. The prevalence of Plasmodium falciparum infection at first antenatal visit was 35.3% in primigravidae and 13.6% in multigravidae (P < 0.001). Mean haemoglobin concentration was significantly lower in primigravidae than in multigravidae (8.8 v. 9.5 g/dl; P < 0.001). Of the 233 women tested for HIV infection, 18.8% of the primigravidae and 23.7% of the multigravidae were seropositive. At delivery, there was no significant difference in parasite prevalence in peripheral or placental blood between women who had received one or two antenatal doses of SP. The multigravidae who had received two doses of SP had higher mean haemoglobin concentrations than those who had received just one (P = 0.009) [this difference was not seen in the primigravidae (P = 0.92)]. However, linear regression analysis indicated that the haematinic supplements given to the subjects contributed more to this increase in haemoglobin concentration than the SP. The mean birthweights were higher, and incidence of LBW lower in babies born to primi-and multi-gravidae who had received two or three doses of SP treatment than those seen in babies born to women who had had just one dose (P < 0.03 for each). The odds ratio for LBW in primigravidae compared with multigravidae decreased from 3.2 to 1.0 as the number of SP doses increased from one to three. The benefit of three doses (compared with none) was equivalent to the population-attributable risk of LBW in primigravidae being reduced from 34.6% to 0%. Subjects who were seropositive for HIV were twice as likely to give birth to LBW babies as the other subjects. The use of SP was not associated with maternal side-effects or perinatal complications. The present results indicate that multiple doses of SP taken during pregnancy will lead to a highly significant reduction in the incidence of LBW in infants born to primigravidae, even if the women have HIV infections. This reduction is observable even when parasite prevalence at delivery is high because of re-infections in late pregnancy; reduction in parasite prevalence earlier in pregnancy, as the result of SP treatment, leads to improved foetal growth.

Low birthweight, preterm births and intrauterine growth retardation in relation to maternal smoking.

The association between the intensity and duration of cigarette smoking during pregnancy and the frequency of low birthweight, preterm births and intrauterine growth retardation was investigated in a historical cohort. All 5166 livebirths occurring in the city of Pelotas, Brazil, during 1993 were identified and mothers interviewed soon after delivery. Children whose mothers smoked during pregnancy had a birthweight 142 g lower than those of non-smoking mothers. The odds ratio for low birthweight among children of smokers was 1.59 [95% CI 1.30-1.95]. There was no association between smoking and preterm delivery assessed by the Dubowitz score. In relation to intrauterine growth retardation, smoking was associated with an odds ratio of 2.07 [95% CI 1.69-2.53]. There was a direct dose-response association between the number of cigarettes smoked and the risk of growth retardation. Women whose partner smoked were also at higher risk of having a child with growth retardation. All the above results were adjusted for confounding factors. The effect of maternal smoking on low birthweight seems to be attributable to intrauterine growth retardation rather than preterm delivery.

Data linkage to explore the risk of low birthweight associated with maternal proximity to hazardous waste sites from the National Priorities List.

Data from the 1988 National Maternal and Infant Health Survey files were linked with data from the 1990 Environmental Protection Agency National Priorities List of hazardous waste sites to determine whether any relationship existed between living in proximity to hazardous waste sites and low birthweight. The odds ratio for low birthweight versus normal birthweight was 1.03 (95% confidence interval [95% CI] = 0.98-1.16), and remained at 0.99 (95% CI = 0.86-1.16) when adjusted for maternal age, parity, infant sex, prenatal care, and behavioral and socioeconomic factors. Very low birthweight, infant and fetal death, prematurity, and congenital malformation were not found to be associated with living in the vicinity of a hazardous waste site during pregnancy. Merging a large population database with environmental data proved to be an innovative but not very efficient method of assessing the risks of low birthweight related to the environment.

Race and birthweight in biracial infants.

The purpose of the study was to determine the role of infant race as a determinant of the Black-White disparity in low birthweight (< 2500 g). Univariate analysis and multivariate logistic regression were performed on Illinois vital records from 1982 and 1983 and on 1980 United States census income data. Fourteen percent of the infants born to Black mothers and White fathers were of low birthweight, compared with 9% of infants born to White mothers and Black fathers and 6% of a random sample of White infants. Both groups of biracial infants were more likely to have been born to unmarried mothers and to reside in very low-income (< $10,000 per year) census tracts than were White infants. When all confounding variables were entered into a logistic model, the adjusted odds ratio of low birthweight for biracial infants born to Black mothers and White fathers equaled 1.4. When biracial infants born to White mothers and Black fathers were compared with White infants, the adjusted odds ratio of low birthweight equaled 1.0. Paternal and consequent infant race does not affect the birthweight distribution of those born to White mothers and Black fathers. Unidentified factors closely related to maternal race underlie the Black-White disparity in infant birthweight.

Caffeine consumption during pregnancy and fetal growth.

The purpose of this study was to examine the association between maternal caffeine consumption and low birthweight, intrauterine growth retardation, and prematurity, adjusting for multiple confounders. Data obtained from birth certificates and interviews on 1,230 women with singleton live births were analyzed to evaluate the potential influence of caffeine consumption during the first trimester on fetal growth. The crude odds ratio for intrauterine growth retardation in infants of women reporting heavy caffeine consumption (greater than 300 mg/day) was 3.86 (95% CI = 1.80, 8.40) which decreased to 2.90 (95% CI = 1.23, 6.87) after controlling for confounding factors. The adjusted odds ratio for low birthweight and heavy maternal caffeine consumption was also elevated (OR = 2.05; 95% CI = 0.86, 4.88). Women who reduced their caffeine intake from greater than 300 mg/day to less than that early in pregnancy had lower risks of delivering infants with either intrauterine growth retardation or low birthweight than women who continued to consume that amount. Preterm delivery appeared to be unrelated to caffeine consumption. Taken together with studies reporting similar findings, these results suggest that heavy caffeine consumption increases the risk for fetal growth retardation.

Unmarried mothers as a high-risk group for adverse pregnancy outcomes

A total of 36,608 singleton births occurring to Black mothers in the District of Columbia in 1980-84 were examined. Infants of unmarried mothers had a 34 percent higher incidence of low birthweight and a 35 percent higher neonatal mortality rate than infants born to married mothers. To delineate the independent effect of marital status, a logit model was fit to 23,461 births occurring to mothers over 19 years of age. Despite controlling on maternal age, educational attainment and adequacy of prenatal care, the odds ratio for low birthweight was 1.18 for the infants of unmarried mothers. Supplemental analyses showed that if mothers were drug addicted or had their first delivery before age 18, the marital status differentials in the birthweights of their infants were no longer significant. These results indicate the importance of unmarried status as a demographic risk factor, and the need for discerning specific high-risk behaviors associated with life styles of unmarried mothers.

The effects of maternal smoking, physical stature, and educational attainment on the incidence of low birth weight.

Data from the 1980 National Natality Survey were used to investigate the effects of maternal smoking, height, weight, and educational attainment on the incidence of low birth weight among white non-Hispanic married mothers aged 20-34 years, live birth order 1-3. Using multiple logistic regression to control for the effects of infant's sex, live birth order, and maternal age, women with less than 12 years education have a low birth weight odds ratio of 2.38 and women with 12 years have a low birth weight odds ratio of 1.24 relative to women with 13 or more years. After further controlling for height, weight, and smoking, these odds ratios are reduced to 1.59 and 1.11, respectively. The majority of the reduction can be attributed to differences in smoking among the education groups. Women with low education are more likely to have smoked prior to pregnancy, more likely to smoke heavily, and less likely to stop smoking during pregnancy. The odds of low birth weight increases by 26% for every five additional cigarettes smoked per day. If all women in the study population stopped smoking during pregnancy, the incidence of low birth weight would be expected to decline by 35% for those with less than 12 years education, by 20% for those with 12 years, and by 11% for those with more than 12 years. The effects of the independent variables were also estimated for two components of low birth weight: below 2,000 grams and 2,000-2,499 grams. Although the nonresponse rate for the National Natality Survey was 20%, a comparison of mail and telephone respondents suggests that the impact of nonresponse on the estimates of the logistic coefficients is minimal.