Relative Risk Of Low Birth Weight Research Articles

Health effects of exposure to indoor volatile organic compounds from 1980 to 2017: A systematic review and meta-analysis.

Exposure to volatile organic compounds (VOCs) indoors is thought to be associated with several adverse health effects. However, we still lack concentration-response (C-R) relationships between VOC levels in civil buildings and various health outcomes. For this paper, we conducted a systematic review and meta-analysis of observational studies to summarize related associations and C-R relationships. Four databases were searched to collect all relevant studies published between January 1980 and December 2017. A total of 39studies were identified in the systematic review, and 32 of these were included in the meta-analysis. We found that the pooled relative risk (RR) for leukemia was 1.03 (95% CI: 1.01-1.05) per 1μg/m3 increase of benzene and 1.25 (95%CI: 1.14-1.37) per 0.1μg/m3 increase of butadiene. The pooled RRs for asthma were 1.08 (95% CI: 1.02-1.14), 1.02 (95% CI: 1.00-1.04), and 1.04 (95% CI: 1.02-1.06) per 1μg/m3 increase of benzene, toluene, and p-dichlorobenzene, respectively. The pooled RR for low birth weight was 1.12 (95% CI: 1.05-1.19) per 1μg/m3 increase of benzene. Our findings provide robust evidence for associations between benzene and leukemia, asthma, and low birth weight, as well as for health effects of some other VOCs.

Survey of Low Birthweight and Extremely Low Birthweight Events in a High Environmental Risk Area of Apulia, Italy

The association between environmental conditions and pregnancy outcome has been under investigation for a long time, but results appear to be inconclusive regarding damage to either the newborn or the mother. The aim of this study was to evaluate the distribution of hospitalization of newborns with low birthweight (< 2500 g) and extremely low birthweight (< 1000 g) in the geographical area of Taranto, Italy, which is characterized by high environmental risk because of industrial pollution. We analyzed the database of hospital discharge forms for the years 2001–2013 regarding hospital admission of newborns in the region of Apulia. The relative risk (RR) of hospitalization, adjusted for the deprivation index, was estimated using the Besag–York–Molliè Bayesian model. The city of Taranto, which has the highest environmental risk, had the highest RR for newborns with low birthweight (1.47, 95% uncertainty interval 1.38–1.56). Other geographical areas with high environmental pollution had higher RRs for low birth weight compared with the regional average. We found no geographical distribution pattern of extremely low birthweight that would suggest an association with environmental pollution.

Maternal plasma lipid levels across pregnancy and the risks of small-for-gestational age and low birth weight: a cohort study from rural Gambia

BackgroundSub-optimal maternal lipid levels during pregnancy may be implicated in the pathophysiological mechanisms leading to low birth weight (LBW) and small-for-gestational-age (SGA). We aimed to determine whether maternal lipid levels across pregnancy were associated with birth weight and the risks of LBW and SGA in rural Gambia.MethodsThis secondary analysis of the ENID trial involved 573 pregnant women with term deliveries. Plasma levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), and triglycerides (TG) were analyzed at enrolment (mean (SD) = 13.9 (3.3) weeks gestation), 20 and 30 weeks gestation as continuous variables and percentile groups. Regression models with adjustment for confounders were used to examine associations between gestational lipid levels and birth weight and the risks of LBW (birth weight < 2500 g) and SGA (<10th percentile INTERGROWTH-21ST for birth weight).ResultsThere were 7.9% LBW and 32.5% SGA infants. At enrolment, every unit increase in HDL-c was associated with a 2.7% (P = 0.011) reduction in relative risk of LBW. At 20 weeks gestation, every unit increase in TC levels was associated with a 1.3% reduction in relative risk of LBW (P = 0.002). Low (<10th percentile) HDL-c at enrolment or at 20 weeks gestation was associated with a 2.6 (P = 0.007) and 3.0 (P = 0.003) times greater risk of LBW, respectively, compared with referent (10th─90th) HDL-c. High (>90th percentile) LDL-c at 30 weeks gestation was associated with a 55% lower risk of SGA compared with referent LDL-c (P = 0.017). Increased levels of TC (β = 1.3, P = 0.027) at 20 weeks gestation and of TC (β = 1.2, P = 0.006) and LDL-c (β = 1.5, P = 0.002) at 30 weeks gestation were all associated with higher birth weight.ConclusionsIn rural Gambia, lipid levels during pregnancy were associated with infant birth weight and the risks of LBW and SGA. Associations varied by lipid class and changed across pregnancy, indicating an adaptive process by which maternal lipids may influence fetal growth and birth outcomes.Trial registrationThis trial was registered as ISRCTN49285450 on: 12/11/2009.

How did Smoking Affect Birth Outcomes in Massachusetts from 1989 to 2004?

Purpose Massachusetts introduced a comprehensive tobacco control program (MTCP) in January 1993. Tobacco smoke is a serious health hazard, particularly for pregnant women. Low birth weight (LBW) is a common condition that has been shown consistently to be causally related to smoking during pregnancy. Methods We calculated population attributable risk (PAR), using the conventional formula in addition to the effect measure, which is relative risk (RR) in this study. Because the database used (Mass CHIP) captures all pregnant women including their smoking status across the state, and also links birth files with death files, this database is a valuable resource for calculating overall smoking prevalence among pregnant women. Infant mortality rates (IMR) from 1989 to 2004 were also calculated. Multiple births and pregnant women with unknown smoking status ( Results More than 91,000 live-births occurred in 1989 as opposed to 78,250 live-births in 2004. Almost 22% of mothers smoked during pregnancy in 1989, reducing to 7.4% in 2004 (66% decline). IMR among smoking mothers declined from 11.6/1000 live-births in 1989 to 5.7 in 2004 (>50% decline), while IMR in non-smoking mothers decreased from 6.7 in 1989 to 4.2/1000 live-births in 2004 (a 37% decline). The proportions of sudden infant death syndrome babies showed a significant annual decline of -6% among non-smokers. The very low LBW babies among smokers showed an annual decline of 8.4% (95%CI: -9.1; -7.7). In the 15-year study period, RR of LBW among smokers has decreased from 2.0 to 1.71 (a 29% overall decline). PAR decreased from 18% to 5% over the 15-year period contributing to almost 300 fewer LBW babies between 1989 and 2004. Conclusion Approximately 300 fewer LBW babies were born between 1989 and 2004 in Massachusetts that could be attributed to reductions in smoking prevalence during pregnancy. Such an effect can also in part be due to the beneficial impact of the MTCP. The fact that almost 5,800 pregnant mothers still continue smoking is of concern. Health promotional activities should be focused on target populations both for an accelerated decline and for a substantial impact.

Association between antenatal depression and low birthweight in a developing country.

Rahman A, Bunn J, Lovel H, Creed F. Association between antenatal depression and low birthweight in a developing country.Objective:There is a high prevalence of depression in south Asian women. We aimed to examine the association between antenatal depression and low birthweight (LBW) in infants in a rural community in Rawalpindi, Pakistan.Method:A total of 143 physically healthy mothers with ICD-10 depression in the third trimester of pregnancy and 147 non-depressed mothers of similar gestation were followed from birth. Infant weight was measured and information collected on socioeconomic status, maternal body-mass index and sociodemographic factors.Results:Infants of depressed mothers had lower birthweight (mean 2910 g) than infants of non-depressed mothers (mean 3022 g). The relative risk for LBW (≤2500 g) in infants of depressed mothers was 1.9 (95% CI 1.3–2.9). The association remained significant after adjustment for confounders by multivariate analyses.Conclusion:Low birthweight is a major public health problem in developing countries. Maternal depression during pregnancy predicts LBW. Interventions aimed at maternal depression may help improve infant outcomes.

Smoking during pregnancy: Missouri longitudinal study.

Maternal smoking during pregnancy has been shown to be associated with reduced birthweight and increased fetal and infant mortality. This paper examines these patterns in first and second maternally-linked singleton pregnancies from 1978 to 1990 among 176,843 Missouri resident women with known smoking status in both pregnancies. Generally women were more likely to smoke in their second pregnancies (27.4%), than in their first (25.8%). This pattern was strongest among those whose first pregnancies occurred as teenagers, and for black women. The relationships of smoking during the first and second pregnancies to outcomes in the second pregnancies were examined primarily through multivariate logistic regression. The adjusted relative risk (RR) of low birthweight (< 2500 g) in the second pregnancy to not smoking in either pregnancy was 1.82 for those who smoked during the second pregnancy only, and 1.87 for those who smoked in both pregnancies. For those who smoked in the first pregnancy only, the RR was 0.97, not significantly different from 1. Adjusted smoking RRs for small-for-gestational age were larger, while adjusted RRs for fetal and neonatal mortality were smaller than the smoking RRs for low birthweight.

Risk factors of sudden infant death in Chinese babies.

The influence of social and biologic factors on sudden infant death was studied in a large Chinese population. Data from all birth certificates in Taiwan from 1988 to 1992 were merged with death certificate data for postneonatal deaths from sudden infant death syndrome and suffocation. The Cox's proportional hazard model was used to compute multivariate adjusted relative risk estimates and 95% confidence intervals. Age difference of parents of more than 10 years was associated with a relative risk (RR) of 1.8 (multivariate adjusted, 95% confidence interval (CI) 1.3-2.3). Better than elementary education for the father was protective (adjusted RR 0.8, 95% CI 0.7-1.0, p < 0.05), and college education of the mother elevated the risk (adjusted RR 1.2, 95% CI 1.0-1.4, p < 0.05). Infants born second to fourth had an adjusted RR of 1.7 (95% CI 1.5-1.9), and infants born fifth or higher had a RR of 2.3 (95% CI 1.5-3.4). The multivariate adjusted RR for low birth weight and prematurity were 2.3 (95% CI 1.9-2.8) and 1.2 (95% CI 1.0-1.5), respectively. Data from this 5-year cohort in Taiwan emphasize biologic and social variables as important risk factors of sudden infant death in Chinese babies.

An Assessment of Low Birthweight Risk in Primiparae as an Indicator of Malaria Control in Pregnancy

Malaria is an important environmental factor which reduces fetal growth in primiparae more than multiparae living under holoendemic conditions for malaria. This relates to greater susceptibility to malaria infection in first pregnancies. The relative risk for low birthweight (less than 2500 g) associated with primiparity is increased in malaria-endemic areas and significantly correlates with the malaria parasite rate at delivery in primiparae. Because of this association, the relative risk is proposed as an indicator to assess malaria control in pregnant women as well as in the community. The sensitivity and specificity of the relative risk for low birthweight in primiparae are calculated for 13 malarious and 15 non-malarious populations. The highest sensitivity and specificity is achieved at a relative risk of 1.7. Social and environmental variables which could alter the sensitivity of the estimate are discussed. Estimates of the population-attributable risk per cent of low birthweight due to malaria in primiparae are calculated and vary between 10% and 40% in endemic areas. The method is applied to observations from malaria-intervention studies in pregnancy in the Solomon Islands and Papua New Guinea and appears sensitive in these prospective studies to changes in malaria prevalence. Calculation of these estimates is straightforward and their use to assess malaria control measures in areas of high transmission has not been suggested previously, it could have wide epidemiological application and requires further field evaluation.