Haemoglobin levels in early pregnancy and severe maternal morbidity: population‐based cohort study

Abstract

Objective Data regarding low maternal haemoglobin concentration and severe maternal morbidity (SMM) are limited and potentially biased. This study evaluated the relation between early maternal haemoglobin concentration and SMM or maternal mortality. Design Population-based cohort study. Setting Ontario, Canada, in a public healthcare system. Population 737 393 births with a routine outpatient haemoglobin measured at a calculated gestational age of 2-16 weeks. Methods The relation between early-pregnancy outpatient blood haemoglobin concentration and each study outcome was expressed as adjusted relative risks (aRR) and absolute risk differences (aRD), with 95% confidence intervals (CI), generated by modified Poisson regression. Main outcome measures The primary outcome was SMM or maternal mortality, from 23 weeks' gestation to 42 days postpartum. Results The mean (SD) haemoglobin concentration was 126.9 (9.3) g/l. Overall, SMM or death occurred in 13 514 pregnancies (1.8%). Relative to a haemoglobin level of 125-129 g/l, the aRR was 1.07 (95% CI 1.02-1.13) and aRD (0.09%, 95% CI 0.01-0.18) at 120-124 g/l; aRR 1.31 (95% CI 1.17-1.46) and aRD 0.47% (95% CI 0.24-0.69) at 105-109 g/l; and aRR 4.53 (95% CI 3.59-5.72) and aRD 5.94% (95% CI 4.12-7.76) at <90 g/l. In all, 5961 women (0.8%) required red cell transfusion, with significantly higher risks at all haemoglobin concentrations below 125-129 g/l, peaking at a haemoglobin level <90 g/l (aRR 11.82, 95% CI 9.30-15.03). Conclusion There is a gradual increase in the risk of SMM or death, as well as red cell transfusion, starting from the lower level of the normal range of haemoglobin of non-pregnant women.

Suboptimal iron deficiency screening in pregnancy and the impact of socioeconomic status in a high-resource setting

“…Of the 44,552 patients, 26,469 (59.4%) had a ferritin checked between 4 weeks prior to and 32 weeks following the index date, with a median ferritin of 36 µg/L (IQR 21-61 µg/L) . 16,525 (62%) of these had a single ferritin test, while 9,944 (38%) had ≥2 ferritin tests in this period. 988 patients had a ferritin greater than 150 µg/L (the upper limit of normal for females used by the laboratory) (Figure 3).…”

“…[8][9][10][11][12][13][14] In two high-resource countries, maternal anemia early in pregnancy has been associated with severe maternal morbidity and mortality, and with increased risk of intellectual disability, autism spectrum disorder and attention deficit/hyperactivity disorder in offspring. 15,16 Moreover, it has been shown that proper management of ID reduces the risk of maternal post-partum blood transfusions and improves neonatal birth weight. 11,17,18 While most prenatal guidelines recommend screening for anemia in pregnancy, recommendations for ID screening are variable, 19 and thus ID screening practices amongst clinicians are inconsistent.…”

Gestational anaemia and severe acute maternal morbidity: a population‐based study*

“…The few previous studies conducted in these countries have focused on specific maternal complications, mainly postpartum haemorrhage, without exploring the association between gestational anaemia and overall severe acute maternal morbidity [14][15][16][17][18]. Moreover, these studies often defined severe maternal complications by specific interventions such as blood transfusion or caesarean section, although these do not directly reflect maternal health status, but rather practices that can vary [15,16,18,19]. Finally, most of these analyses used retrospective data extracted from administrative databases, without information about the time sequence of events between anaemia and severe maternal complications and with limited control for confounding factors [14][15][16][17][18].…”

The definition, screening, and treatment of postpartum anemia: A systematic review of guidelines

“…It is accepted that antepartum anemia and mode of delivery (instrumental delivery and cesarean birth) are major risk factors for postpartum anemia 26,29,30 . Antenatal anemia increases the risk of bleeding, 30 and low Hb levels are independently associated with the need for transfusion after a cesarean 31 .…”

“…It is accepted that antepartum anemia and mode of delivery (instrumental delivery and cesarean birth) are major risk factors for postpartum anemia 26,29,30 . Antenatal anemia increases the risk of bleeding, 30 and low Hb levels are independently associated with the need for transfusion after a cesarean 31 . It is probable that including prenatal anemia and cesarean birth in the selective screening criteria could improve the cost‐effectiveness balance, not just in the short term, but in the medium and long term as well 25–27,30,31 …”