Results
82·9, anaemia, death, bleeding, anaemic cardiac failure, HELLP syndrome, pre-eclampsia, blood loss, macrosomia, infection, sepsis, placenta abnormalities
ANAEMIA, HELLP SYNDROME, BLEEDING, PRE-ECLAMPSIA, HYPERTENSIVE DISEASE, BLOOD LOSS, ANTEPARTUM HAEMORRHAGE, ANTEPARTUM HAEMORRHAGE, MICROANGIOPATHIC HAEMOLYTIC ANAEMIA, INFECTION, REGRESSION, SEPSIS, POSTPARTUM HAEMORRHAGE, ACUTE RESPIRATORY DISTRESS SYNDROME
A total of 10 620 women were recruited to the WOMAN-2 trial between Aug 24, 2019, and Nov 1, 2022, of whom 10 561 (99·4%) had complete outcome data. 8751 (82·9%) of 10 561 women were recruited from hospitals in Pakistan, 837 (7·9%) from hospitals in Nigeria, 525 (5·0%) from hospitals in Tanzania, and 448 (4·2%) from hospitals in Zambia. Baseline characteristics are presented in Baseline characteristicsData are mean (SD) or n (%). For infection status, hypertensive disease, assisted delivery, induction, and augmentation, proportions will not sum to 100% as responses are not mutually exclusive. For other variables proportions might not sum to 100% due to rounding.742 (7·0%) women had a clinical postpartum haemorrhage. Mean prebirth haemoglobin for women with clinical postpartum haemorrhage was 76·4 g/L (SD 13·8). The risk of clinical postpartum haemorrhage was 6·2% (544 of 8791) in women with moderate anaemia and 11·2% (198 of 1770) in women with severe anaemia. The primary diagnosis for postpartum haemorrhage by anaemia status is shown in Primary cause of postpartum haemorrhageData are n (%).14 women died (six with moderate anaemia and eight with severe anaemia), in whom the mean prebirth haemoglobin was 68·4 g/L (SD 19·1). Primary causes of death were bleeding (eight women), anaemic cardiac failure (two women), acute respiratory distress syndrome (two women), HELLP syndrome (one woman; defined as pre-eclampsia characterised by microangiopathic haemolytic anaemia, elevated liver enzymes, and low platelets), and sepsis (one woman). Compared with moderate anaemia, severe anaemia was associated with an increased odds of death (OR 6·65 [95% CI 2·30–19·18]). For the nine women who died and had clinical postpartum haemorrhage, mean haemoglobin was 70·0 g/L (SD 17·4). For the eight women who died and had bleeding as their cause of death, mean haemoglobin was 66·6 g/L (SD 17·3). 68 women died or had a near miss, in whom mean haemoglobin was 65·0 g/L (SD 18·1). Severe anaemia was associated with a seven times higher increased odds of death or near miss (OR 7·25 [95% CI 4·45–11·80]) than was moderate anaemia.Estimated blood loss by anaemia severity is shown in Bar chart of estimated blood loss stratified by anaemia status170 women with estimated blood loss of 1 L or more and six women with a missing estimated blood loss value are omitted (n=10 385).Univariable and multivariable analyses of risk factors for postpartum haemorrhage are shown in Univariable and multivariable analyses of risk factors for clinical postpartum haemorrhage in women with moderate or severe anaemiaThe multivariable model controls for haemoglobin, country, BMI, number of fetuses, parity, previous postpartum haemorrhage, placenta abnormalities, any antepartum haemorrhage, previous caesarean sections, any current infection, hypertensive disease, assisted delivery, augmentation or induction, episiotomy, long labour and known macrosomia. n=10 561 for the univariable model and n=10 405 for the multivariable model. aOR=adjusted odds ratio.Univariable and multivariable analyses of risk factors for WHO-defined postpartum haemorrhage in women with moderate or severe anaemiaWHO-defined postpartum haemorrhage is defined as blood loss of at least 500 mL in the first 24 h after giving birth. The multivariable model controls for haemoglobin, country, BMI, number of fetuses, parity, previous postpartum haemorrhage, placenta abnormalities, any antepartum haemorrhage, previous caesarean sections, any current infection, hypertensive disease, assisted delivery, augmentation or induction, episiotomy, long labour, and known macrosomia. n=10 555 for the univariable model and n=10 399 for the multivariable model. aOR=adjusted odds ratio.Univariable and multivariable analyses of risk factors for calculated postpartum haemorrhage in women with moderate or severe anaemiaCalculated postpartum haemorrhage is defined as calculated estimated blood loss of at least 1000 mL. The multivariable model controls for haemoglobin, country, BMI, number of fetuses, parity, previous postpartum haemorrhage, placenta abnormalities, any antepartum haemorrhage, previous caesarean sections, any current infection, hypertensive disease, assisted delivery, augmentation or induction, episiotomy, long labour, and known macrosomia. n=10 408 for the univariable model and n=10 254 for the multivariable model. aOR=adjusted odds ratio.Antepartum haemorrhage, placenta abnormalities, and current infection might be on the causal pathway between anaemia and postpartum haemorrhage in which case controlling for these factors would be inappropriate. When we conducted a post-hoc sensitivity analysis excluding these factors from the multivariable model (We found no evidence of variable collinearity. The maximum variance inflation factor was 3·0 for abnormal placenta in the multivariable model with the outcome clinical postpartum haemorrhage. When we corrected for HemoCue inaccuracy, a 10 g/L reduction in prebirth haemoglobin increased both the unadjusted (OR 1·30 [95% CI 1·22–1·40]) and the adjusted (aOR 1·22 [1·14–1·32]) odds of clinical postpartum haemorrhage.The relationship between prebirth haemoglobin and postpartum haemorrhage is presented in Percentage of women with postpartum haemorrhage versus prebirth haemoglobin concentrationClinical postpartum haemorrhage is defined as an estimated blood loss of at least 500 mL or any blood loss sufficient to compromise haemodynamic stability. WHO-defined postpartum haemorrhage is defined as blood loss of at least 500 mL in the first 24 h after giving birth. Calculated clinical postpartum haemorrhage is defined as calculated estimated blood loss of at least 1000 mL. For clinical postpartum haemorrhage, n=10 561; for WHO-defined postpartum haemorrhage, n=10 555; for calculated postpartum haemorrhage, n=10 408. The numbers of women with postpartum haemorrhage are displayed on the histogram bars.The association between prebirth haemoglobin and clinical postpartum haemorrhage in women with (n=4564) and without (n=5997) one or more risk factors is presented in Relationship between haemoglobin and risk of clinical postpartum haemorrhageThe risk of postpartum haemorrhage is calculated using logistic regression with a quadratic term for haemoglobin. The red is the postpartum haemorrhage risk in 4564 women with one or more risk factors (previous postpartum haemorrhage, abnormal placenta, antepartum haemorrhage, infection, multiple pregnancy, and primigravida). The blue line is the risk of postpartum haemorrhage in 5997 women without risk factors. The shaded areas are 95% CIs.