The WOMAN-2 trial collaborators, ‘Maternal anaemia and the risk of postpartum haemorrhage: a cohort analysis of data from the WOMAN-2 trial’, The Lancet, June 27, 2023, doi.org/10.1016/S2214-109X(23)00245-0
Of late anaemia has been in the news in India, what with the government proposing to remove a question on it from the National Family Health Survey (NFHS) and instead do a more elaborate test to determine haemoglobin levels in the blood as part of the Diet and Biomarker (DAB) survey. A paper recommending that normative values for haemoglobin must be lowered in India, based on a small study, has also come in for criticism. The WhatsApp groups of two professional sectors, where repartees have been flying hard and fast are those belonging to nutritionists and obstetricians and gynaecologists. The latter groups who have actually seen the impact of anaemia especially on maternal and infant health have been articulating their views on keeping the standards for anaemia, and to not amend them based on a statistically insignificant study. Policy makers in India must allow the results of a multi-country study published recently in The Lancet to inform their rules on measuring anaemia, handling it and making sure the interventions are sensible and far reaching.
Anaemia and pregnancy
Anaemia has a very strong link with postpartum haemorrhage (excessive vaginal bleeding after delivery), and the risk of death or near miss is very high.
As per the study, by the WOMAN (World Maternal Antifibrinolytic )-2 trial collaborators, worldwide, more than half a billion women of reproductive age are anaemic. Each year, about 70,000 women who give birth die from postpartum haemorrhage, almost all of them in low-and middle-income countries. While a known risk of anaemia or low haemoglobin levels is postpartum death, researchers decided to examine in detail the association between anaemia and the risk of postpartum haemorrhage.
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This trial enrolled over 10,000 women with moderate or severe anaemia giving birth vaginally in hospitals in Pakistan, Nigeria, Tanzania, and Zambia, countries where anaemia in pregnancy was common and established by other trials. They examined the continuous association between prebirth haemoglobin and the risk of postpartum haemorrhage in a large cohort of women from low-and middle-income countries. The advantage of examining anaemia as a continuous variable, the authors argued, is that demonstration of a monotonic biological gradient is more suggestive of a causal relationship. The outcome was defined as an occurrence of postpartum haemorrhage, defined in three ways: “clinical postpartum haemorrhage (estimated blood loss ≥500 mL or any blood loss sufficient to compromise haemodynamic stability); WHO-defined postpartum haemorrhage (estimated blood loss of at least 500 mL); and calculated postpartum haemorrhage (blood loss of ≥1,000 mL).
Blood loss and shock
The mean age of the women from Pakistan, Nigeria, Tanzania and Zambia was just over 27 years. There was clear evidence from the study that lower haemoglobin values had a direct relationship with volume blood loss, and clinical postpartum haemorrhage. “We found that with decreasing maternal haemoglobin concentration, the risk of postpartum haemorrhage increases monotonically,” the authors recorded.
Anaemia reportedly reduces the oxygen-carrying capacity of blood, and therefore, women with anaemia cannot tolerate the same volume of bleeding as healthy women, and become shocked after a smaller volume blood loss, the authors reasoned. Further they added, “Given the lack of an established definition of postpartum haemorrhage in women with anaemia, before conducting this study, we examined different definitions of postpartum haemorrhage in terms of their specificity for substantial bleeding, and their association with fatigue, physical endurance, and breathlessness.” They eventually found that a clinical diagnosis of postpartum haemorrhage was highly specific for clinical signs of shock and irrevocably associated with worse maternal function.
The mean estimated blood loss post delivery was 301 mL for the 8,791 (3.2%) women with moderate anaemia and 340 mL for the 1,770 (16.8%) women with severe anaemia. 742 (7.0% of the total) women had clinical postpartum haemorrhage. The risk of clinical postpartum haemorrhage was 6.2% in women with moderate anaemia and higher, 11.2% in women with severe anaemia. Fourteen women died and 68 either died or had a near miss. Severe anaemia was associated with seven times higher odds of death or near miss than was moderate anaemia. Researchers further said that a 10 g/L reduction in prebirth haemoglobin increased the odds of clinical postpartum haemorrhage.
The authors went on to recommend that attention should be given to the prevention and treatment of anaemia in women once they hit reproductive age.
Preventing anaemia
The Indian government has a well-structured project to provide weekly iron and folic acid supplements to adolescent girls (and boys), in order to tackle the looming crisis of anaemia. The climb to a barely-acceptable haemoglobin content of 12 for women seems very steep, given the nutrition status of these children, primarily in rural areas, where quality and quantity of what they eat is less than ideal,and is only exacerbated by malabsorption, public health, experts added.
The task has already been cut out for the Indian public health programme. Health managers are aware of the risks of anaemia and know what to do to handle it. However, the rising levels of anaemia in the country is a source of concern and mandates that any project to bring down anaemia in the country must be on mission mode. The solution is not to bring down the gold standard laboratory readings literally. While the argument to detach anaemia from the NFHS is that the DAB would be undertaking a more elaborate blood draw to measure haemoglobin levels accurately, the argument against it is also that such a measure may not be feasible for a large group of people, who may say okay to a capillary blood draw (finger prick) but baulk at a venous blood drawal. Any public outreach programme must be mindful of the cultural, social realities and have a sense of the attitudes of the people they are targeting. If these factors are not sewn into a public health programme, the outcomes may be far from what was sought or planned, experts said.
