Reduction In Low Birth Weight Research Articles

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.

Maternal nutrition and birth weight.

Low birth weight (LBW) babies (2500 gm or less at birth) are more likely to die and suffer sequelae. Intrauterine growth retardation (IUGR) babies also weight the same, but they are born at 37 weeks or over. Small for gestational age (SGA) is a related term used for babies weighing less than expected. 20.6 million LBW babies were born in 1979, most of then in developing countries. In the US, 12.1% of nonwhites vs. 6% of whites had LBW babies in 1980 (50% of infant deaths were attributed to LBWs). A study in Guatemala showed that LBWs accounted for 88% of neonatal deaths. 15-21% of the US decline in neonatal mortality since the 1960s was due to birth weight distribution. 50% of the decline in Alabama was attributable to improved obstetrical care from 1970 to 1980. 12,000 Finnish children were followed up for 14 years, and those born with weights below the mean had significantly higher mortality than normal weight children. The saving of very LBW babies by medical technology has raised ethical questions, as many have mental and physical retardation and the expenses are enormous. SGAs have smaller stature IUGR/low ponderal index infants had 2.9-5.7 times the mortality of full-term normal infants, and they also had poorer academic progress, but IUGR/adequate ponderal index babies fared even worse. Such afflictions carry across generations, as evidenced by a Seattle study on 748 white women indicating impaired reproductive performance of female infants. Some of the components producing LBW are: maternal genetic, social, cultural, and nutritional factors, smoking, and dieting during pregnancy, wars and famines (e.g., Leningrad and Wuppertal during and after World War II). Anthropometric studies indicate that mothers with greater body size have larger babies, but genetics also play a role here. Intervention studies confirmed the importance of nutrition: in a Mexican study and increase of 180 gm of birth weight and 29.6% reduction of LBW was produced by supplementation during pregnancy. Ethnic differences in the development of the newborn are worth studying after discounting confounding factors.

Low birth weight in pregnancies following induced abortion: no evidence for an association.

Compared with women delivering a first pregnancy, those delivering a second pregnancy after aborting the first have similar rates of low (less than 2,500 g) birth weight newborns (relative risk (RR) G2A1/G1 = 0.86, 95% confidence interval (CI) = 0.49-1.51) and mean birth weight (delta = 16.3 g, p = 0.63). Abortion of the first pregnancy prevents the reduction in low birth weight and increase in mean birth weight in the second pregnancy which delivery of the first pregnancy normally bestows (RR G2P1/G2A1 = 0.48, 95% CI = 0.25-0.90; delta = 135.3 g, p less than 0.0001). Two prior induced abortions do not significantly increase risk for low birth weight (RR G3A2/G1 = 1.14, 95% CI = 0.37-3.56) or decrease mean birth weight (delta = 29.0 g), compared with women delivering their first pregnancy. The second of two deliveries has a reduced risk of low birth weight irrespective of whether both deliveries follow an aborted first pregnancy. Adjustment for confounding factors did not materially change these results. Low birth weight rates were higher after abortions performed in hospital compared with elsewhere (p = 0.03), but mean birth weight was not affected. Gestation at abortion, vacuum aspiration or dilatation and curettage, and abortion complications were unrelated to birth weight of subsequent pregnancies. Pregnancies conceived within six months of a prior abortion or delivery had lower birth weight than if the antecedent pregnancy ended more than six months previously.