Philip Steer, professor, M Ash Alam, medical student, b Jane Wadsworth, senior lecturer, c Anne Welch, research assistant d
to the Academic Department of Obstetrics and Gynaecology, Charing Cross and Westminster Medical School, Chelsea and Westminster Hospital, London SW10 9NH, b St Bartholomew's Hospital Medical College, London EC1A 7Be, c Academic Department of Public Health, St Mary's Hospital Medical School, London W2 1PG, d Academic Department of Obstetrics and Gynaecology, St Mary's Hospital Medical School, London W2 1PG
Abstract
Design: Retrospective analysis of 153,602 pregnancies in women of different ethnic groups and birth weight of their children. The data were taken a regional database from 1988-91. The measurement of hemoglobin taken into account was the lowest obtained during pregnancy.
Location: Northeast Thames. Show
: 115,262 white women, 22,206 Indo-Pakistanis, 4570 Afro-Caribbean, Mediterranean 2642, 3,905 African black women, 2,351 Oriental and 2,666 from other ethnic groups.
Size: was considered low birth weight (<2500> Results: The mean birth weight in children of white women was higher hemoglobin levels during pregnancy under the age of 85-95 g / l; the lowest incidence of low birth weight and premature births took place in the group whose hemoglobin concentration during pregnancy was less than 95-105 g / l. In all ethnic groups showed a similar pattern of results.
Conclusions: The magnitude of the drop in hemoglobin levels during pregnancy is associated with birth weight, the difficulty of the body to maintain hemoglobin concentration below 105 g / l indicates an increased risk low birth weight and premature birth. This phenomenon is observed in all ethnic groups. Some ethnic groups have higher rates of low birth weight and premature births than women white, but also have higher concentrations of hemoglobin. The increase in the rate of "anemia," does not explain the higher rates of low birth weight that occur with any type of hemoglobin.
key ideas
- Failure to reduce body hemoglobin concentration during pregnancy increases the incidence of low birth weight and preterm births
- Routine administration of iron supplements during pregnancy is unnecessary in terms of fetal development in most of the pregnancy.
- could mean corpuscular volume be a better indicator of iron deficiency in the mother, but would require a prospective study in this regard.
Introduction
In a normal pregnancy which is not given to the mother no iron supplementation, hemoglobin levels in maternal blood down from average levels before pregnancy to 133 g / l to an average of 110 g / l at 36 weeks. 1 hemoglobin concentration decreases shortly before 20 weeks, is held constant until week 30 and then gradually descends 3 Therefore, any measure of hemoglobin performed after 20 weeks is reasonably representative of the decrease induced by pregnancy. If this decline may be considered or not, "Anaemia" remains a controversial issue. The World Health Organization in its report Nutritional 1972, suggested that we can consider that a pregnant woman is anemic when their hemoglobin levels drop below the 110 g / l 4 , [...] A recent study of 8,684 pregnant women in Oxford (one of the busiest areas in the UK) suggested that 47% of women had iron deficiency having adverse effects on the ratio of placental weight / birth weight, which could lead to suffering hypertension later. 5
supplementation with iron and folic acid in pregnant women reduced by 5% the incidence of hemoglobin levels below 110g / l. 1 Therefore, routine prophylaxis is commonly referred 7 In contrast, a recent review of 20 randomized controlled studies contributed to the conclusion that "routine supplementation has no detectable effect on maternal health and not in fetal or in particular, to prevent premature birth, low birth weight or neonatal morbidity. Available data from clinical studies provide no evidence to support routine iron supplementation versus supplementation selective. [...] The routine supplementation should be granted only in cases where iron deficiency is common in the population. "
8 [...]
Discussion Our study shows a strong association between weight birth and the hemoglobin concentration during pregnancy. Not only is an increase of between 5 and 7 times in premature births and low birth weight babies if the lower hemoglobin concentration during pregnancy remained above 145 g / l but the concentration of hemoglobin associated with increased fetal weight (86-95 g / l) were lower than is commonly appreciated. Fetal weight is, by itself, the most important determinant of mortality during the first year of life, 9 and appears to be a good indicator of the efficiency of a woman to "hold" the fetus, according to this criterion, a decreased hemoglobin level below 100 g / l in the second quarter stops optimal. This fact probably reflects a good expansion / increase in plasma volume. 10 11 The failure to lower hemoglobin levels below "optimal" are also associated with an increased risk of pre-eclampsia, 12 the birth of children of low gestational age, 12 13 14 15 17 16 and premature birth. 9 18 [...] The mechanism by which plasma volume expansion promotes fetal growth is still unknown, but could be a reduction of blood viscosity, promoting their movement at a slower rate in space between the blood vessels of the mother and fetus.
hemoglobin concentrations below 95 g / l appear to be remarkably safe. Our study shows that, although low hemoglobin levels are more common in certain ethnic groups, especially women African, Afro-Caribbean, and Indo-Pakistanis, this does not explain the increase in preterm births and low birth weight in these groups because they remain the same TAS in different subgroups with different concentrations of hemoglobin. Birth weight and gestation length are genetically programmed to be different in these groups, and there are significant physiological differences, so that the worst results in terms of perinatal mortality should be analyzed in more detailed studies on neonatal morbidity. Many authors have stressed that more attention should be paid to high hemoglobin levels during pregnancy to low 9 12 13 14 15 16 18 17 and some have argued against the routine use of iron supplements during pregnancy. 19 20 21 [...] Continue
anemia may feel genuine (not a low concentration of hemoglobin) have adverse effects on fetal growth, as suggested by Godfrey et al. 5 is necessary, therefore, a more specific definition. Ferritin is not a useful measure because it also drops significantly during pregnancy, regardless of whether or not a supplement of iron. Without 22 However, the mean corpuscular volume remains constant, 22 so it could be a more robust indicator, although it can be confusing if the bulky effect of concurrent deficiency of folate. Studies are needed that relate the proposed variables fetal and neonatal function to replace some other deceptive variables.
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