Association between maternal haemoglobin and stillbirth: a cohort study among a multi-ethnic population in England

Screening and treatment of iron deficiency anemia in pregnancy: A review and appraisal of current international guidelines

Iron deficiency anemia (IDA) in pregnancy is a common diagnosis that is associated with adverse obstetric and neonatal outcomes. There remains uncertainty regarding how best to screen for, prevent, and treat established IDA in pregnancy. There is no consensus on the benefits of routine iron supplementation in pregnancy, with concerns regarding potential harmful effects of routine iron supplementation in women who are iron replete. Fourteen international guidelines were selected and appraised and compared by a multidisciplinary team. The AGREE II GRS tool was used. Each reviewer independently made their own assessment, and the scores from 1 to 7 were also collated and averaged for an overall score incorporating seven domains: process of development, clarity of presentation, completeness of reporting, clinical validity, and overall quality. The reviewers' scores were also individually compared according to discipline. The mean score across all the guidelines was 4.4 (range 3.5-6.5). Only half of the guidelines recommend routine iron in pregnancy. In terms of screening recommendations, five guidelines recommend screening with ferritin in addition to a full blood count in pregnancy, two recommend selective screening with ferritin for at risk groups only, and one guideline suggests using ferritin where feasible. Although many of the guidelines recommend similar doses of oral elemental iron of 100-200 mg daily for the treatment of established IDA in pregnancy, two recommend twice or three times daily dosing. Only five guidelines give hemoglobin rises to expect within specific timeframes. There remains a need to clarify the optimal screening method, dosing regimen, timing, and route of iron supplementation in pregnancy. Robust randomized controlled data are needed to guide appropriate prevention and management.

Maternal and fetal factors associated with stillbirth in singleton pregnancies in 13 hospitals across six states in India: A prospective cohort study

OBJECTIVE

This study aimed to investigate the incidence of and risk factors for stillbirth in an Indian population.

METHODS

We conducted a secondary data analysis of a hospital-based cohort from the Maternal and Perinatal Health Research collaboration, India (MaatHRI), including pregnant women who gave birth between October 2018-September 2023. Data from 9823 singleton pregnancies recruited from 13 hospitals across six Indian states were included. Univariable and multivariable Poisson regression analysis were performed to examine the relationship between stillbirth and potential risk factors. Model prediction was assessed using the area under the receiver-operating characteristic (AUROC) curve.

RESULTS

There were 216 stillbirths (48 antepartum and 168 intrapartum) in the study population, representing an overall stillbirth rate of 22.0 per 1000 total births (95% confidence interval [CI]: 19.2-25.1). Modifiable risk factors for stillbirth were: receiving less than four antenatal check-ups (adjusted relative risk [aRR]: 1.75, 95% CI: 1.25-2.47), not taking any iron and folic acid supplementation during pregnancy (aRR: 7.23, 95% CI: 2.12-45.33) and having severe anemia in the third trimester (aRR: 3.37, 95% CI: 1.97-6.11). Having pregnancy/fetal complications such as hypertensive disorders of pregnancy (aRR: 1.59, 95% CI: 1.03-2.36), preterm birth (aRR: 4.41, 95% CI: 3.21-6.08) and birth weight below the 10th percentile for gestational age (aRR: 1.35, 95% CI: 1.02-1.79) were also associated with an increased risk of stillbirth. Identified risk factors explained 78.2% (95% CI: 75.0%-81.4%) of the risk of stillbirth in the population.

CONCLUSION

Addressing potentially modifiable antenatal factors could reduce the risk of stillbirths in India.

Anemia in Pregnancy With CKD

Chronic kidney disease (CKD), anemia, and iron deficiency are global health issues affecting individuals in both high-income and low-income countries. In pregnancy, both CKD and iron deficiency anemia increase the risk of adverse maternal and neonatal outcomes, including increased maternal morbidity and mortality, stillbirth, perinatal death, preterm birth, and low birthweight. However, it is unknown to which extent iron deficiency anemia contributes to adverse outcomes in CKD pregnancy. Furthermore, little is known regarding the prevalence, pathophysiology, and treatment of iron deficiency and anemia in pregnant women with CKD. Therefore, there are many unanswered questions regarding optimal management with oral or i.v. iron and recombinant human erythropoietin (rhEPO) in these women. In this review, we present a short overview of the (patho)physiology of anemia in healthy pregnancy and in people living with CKD. We present an evaluation of the literature on iron deficiency, anemia, and nutritional deficits in pregnant women with CKD; and we evaluate current knowledge gaps. Finally, we propose research priorities regarding anemia in pregnant women with CKD.

The impact of recommending iron supplements to women with depleted iron stores in early pregnancy on use of supplements, and factors associated with changes in iron status from early pregnancy to postpartum in a multi-ethnic population-based cohort

BACKGROUND

We aimed to evaluate the impact of recommending supplementation to pregnant women with serum ferritin (SF) < 20 µg/L in early pregnancy on use of supplements, and to explore which factors were associated with changes in iron status by different iron indicators to 14 weeks postpartum.

METHODS

A multi-ethnic population-based cohort study of 573 pregnant women examined at mean gestational week (GW) 15 (enrolment), at mean GW 28 and at the postpartum visit (mean 14 weeks after delivery). Women with SF < 20 µg/L at enrolment were recommended 30-50 mg iron supplementation and supplement use was assessed at all visits. Change of SF, soluble transferrin receptor and total body iron from enrolment to postpartum were calculated by subtracting the concentrations at the postpartum visit from that at enrolment. Linear and logistic regression analyses were performed to assess associations between use of supplements in GW 28 and changes in iron status and postpartum iron deficiency/anaemia. Change of iron status was categorized into 'steady low', 'improvement', 'deterioration', and 'steady high' based on SF status at enrolment and postpartum. Multinomial logistic regression analyses were performed to identify factors associated with change of iron status.

RESULTS

At enrolment, 44% had SF < 20 µg/L. Among these women (78% non-Western European origin), use of supplements increased from 25% (enrolment) to 65% (GW 28). Use of supplements in GW 28 was associated with improved iron levels by all three indicators (p < 0.05) and with haemoglobin concentration (p < 0.001) from enrolment to postpartum, and with lower odds of postpartum iron deficiency by SF and TBI (p < 0.05). Factors positively associated with 'steady low' were: use of supplements, postpartum haemorrhage, an unhealthy dietary pattern and South Asian ethnicity (p ≤ 0.01 for all); with 'deterioration': postpartum haemorrhage, an unhealthy dietary pattern, primiparity and no use of supplements (p < 0.01 for all), and with 'improvement': use of supplements, multiparity and South Asian ethnicity (p < 0.03 for all).

CONCLUSIONS

Both supplement use and iron status improved from enrolment to the postpartum visit among women recommended supplementation. Dietary pattern, use of supplements, ethnicity, parity and postpartum haemorrhage were identified as factors associated with change in iron status.

Maternal low and high hemoglobin concentrations and associations with adverse maternal and infant health outcomes: an updated global systematic review and meta-analysis

BACKGROUND

Growing evidence suggests low and high maternal hemoglobin (Hb) concentrations may have adverse consequences for maternal and child health. There remain questions on specific Hb thresholds to define anemia and high Hb as well as how cutoffs may vary by anemia etiology and timing of assessment.

METHODS

We conducted an updated systematic review (using PubMed and Cochrane Review) on low (< 110 g/L) and high (≥ 130 g/L) maternal Hb concentrations and associations with a range of maternal and infant health outcomes. We examined associations by timing of Hb assessment (preconception; first, second, and third trimesters, as well as at any time point in pregnancy), varying cutoffs used for defining low and high hemoglobin concentrations and performed stratified analyses by iron-deficiency anemia. We conducted meta-analyses to obtain odds ratios (OR) and 95% confidence intervals.

RESULTS

The updated systematic review included 148 studies. Low maternal Hb at any time point in pregnancy was associated with: low birthweight, LBW (OR (95% CI) 1.28 (1.22-1.35)), very low birthweight, VLBW (2.15 (1.47-3.13)), preterm birth, PTB (1.35 (1.29-1.42)), small-for-gestational age, SGA (1.11 (1.02-1.19)), stillbirth 1.43 (1.24-1.65)), perinatal mortality (1.75 (1.28-2.39)), neonatal mortality (1.25 (1.16-1.34), postpartum hemorrhage (1.69 (1.45-1.97)), transfusion (3.68 (2.58-5.26)), pre-eclampsia (1.57 (1.23-2.01)), and prenatal depression (1.44 (1.24-1.68)). For maternal mortality, the OR was higher for Hb < 90 (4.83 (2.17-10.74)) than for Hb < 100 (2.87 (1.08-7.67)). High maternal Hb was associated with: VLBW (1.35 (1.16-1.57)), PTB (1.12 (1.00-1.25)), SGA (1.17 (1.09-1.25)), stillbirth (1.32 (1.09-1.60)), maternal mortality (2.01 (1.12-3.61)), gestational diabetes (1.71 (1.19-2.46)), and pre-eclampsia (1.34 (1.16-1.56)). Stronger associations were noted earlier in pregnancy for low Hb and adverse birth outcomes while the role of timing of high Hb was inconsistent. Lower Hb cutoffs were associated with greater odds of poor outcomes; for high Hb, data were too limited to identify patterns. Information on anemia etiology was limited; relationships did not vary by iron-deficiency anemia.

CONCLUSION

Both low and high maternal Hb concentrations during pregnancy are strong predictors of adverse maternal and infant health outcomes. Additional research is needed to establish healthy reference ranges and design effective interventions to optimize maternal Hb during pregnancy.

Variation Patterns of Hemoglobin Levels by Gestational Age during Pregnancy: A Cross-Sectional Analysis of a Multi-Center Retrospective Cohort Study in China

Background: Pregnancy anemia is a global health concern. However, to our knowledge, there still has little consensus on the reference value of hemoglobin levels. Particularly, little evidence from China was accessible in most existing guidelines. Objective: To evaluate hemoglobin levels and anemia prevalence of pregnant women in China and offer evidence for anemia and its reference values in China. Methods: A multi-center retrospective cohort study was conducted among 143,307 singleton pregnant women aged 15–49 at 139 hospitals in China, with hemoglobin concentrations routinely tested at each prenatal visit. Subsequently, a restricted cubic spline was performed to reveal a non-linear variation of hemoglobin concentrations during the gestational week. The Loess model was used to describe the changes in the prevalence of different degrees of anemia with gestational age. Multivariate linear regression model and Logistic regression model were applied to explore influencing factors of gestational changes in hemoglobin level and anemia prevalence, respectively. Results: Hemoglobin varied nonlinearly with gestational age, and the mean hemoglobin levels decreased from 125.75 g/L in the first trimester to 118.71 g/L in the third trimester. By analyzing hemoglobin levels with gestational age and pregnancy period, we proposed new criteria according to 5th percentile hemoglobin concentration in each trimester as a reference for anemia, with 108 g/L, 103 g/L, and 99 g/L, respectively. According to WHO’s criteria, the prevalence of anemia sustainably increased with gestational age, with 6.2% (4083/65,691) in the first trimester, 11.5% (7974/69,184) in the second trimester and 21.9% (12,295/56,042) in the third trimester, respectively. In subsequent analysis, pregnant women in non-urban residents, multiparity, and pre-pregnancy underweight tended to have lower hemoglobin levels. Conclusions: This research, the first large-sample study to present a set of gestational age-specific reference centiles for hemoglobin levels in China, could be used to obtain a better understanding of the overall levels of hemoglobin in Chinese healthy pregnant women and ultimately offer clues for a more precise hemoglobin reference value of anemia in China.

Maternal hemoglobin levels and adverse pregnancy outcomes: individual patient data analysis from 2 prospective UK pregnancy cohorts

BACKGROUND

Hemoglobin (Hb) is a modifiable risk factor for adverse pregnancy outcomes. Studies have reported conflicting associations between maternal Hb levels and adverse pregnancy outcomes, including preterm birth (PTB), low birth weight (LBW), and perinatal mortality.

OBJECTIVE

In this study, we aimed to estimate the shape and magnitude of associations between maternal Hb levels in early (7-12 wk gestation) and late pregnancy (27-32 wk gestation) and pregnancy outcomes in a high-income setting.

METHODS

We used data from 2 UK population-based pregnancy cohorts: the Avon Longitudinal Study of Parents and Children (ALSPAC) and Pregnancy Outcome Prediction Study (POPS). We used multivariable logistic regression models to examine the relationship between Hb and pregnancy outcomes, adjusting for maternal age, ethnicity, BMI, smoking status, and parity. Main outcome measures were PTB, LBW, small for gestational age (SGA), pre-eclampsia (PET), and gestational diabetes mellitus (GDM).

RESULTS

Mean Hb in ALSPAC were 12.5 g/dL (SD = 0.90) and 11.2 g/dL (SD = 0.92) in early and late pregnancy, respectively, and 12.7 g/dL (SD = 0.82) and 11.4 g/dL (SD = 0.82) in POPS. In the pooled analysis, there was no evidence of associations between a higher Hb in early pregnancy (7-12 wk gestation) and PTB (OR per 1 g/dL of Hb: 1.09; 95% CI: 0.97, 1.22), LBW (1.12: 0.99, 1.26), and SGA (1.06; 0.97, 1.15). Higher Hb in late pregnancy (27-32 wk gestation) was associated with PTB (1.45: 1.30, 1.62), LBW (1.77: 1.57, 2.01), and SGA (1.45: 1.33, 1.58). Higher Hb in early and late pregnancy was associated with PET in ALSPAC (1.36: 1.12, 1.64) and (1.53: 1.29, 1.82), respectively, but not in POPS (1.17:0.99, 1.37) and (1.03: 0.86, 1.23). There was an association with a higher Hb and GDM in ALSPAC in both early and late pregnancy [(1.51: 1.08, 2.11) and (1.35: 1.01, 1.79), respectively], but not in POPS [(0.98: 0.81, 1.19) and (0.83: 0.68, 1.02)].

CONCLUSIONS

Higher maternal Hb may identify the risk of adverse pregnancy outcomes. Further research is required to investigate if this association is causal and to identify the underlying mechanisms.

Clinical risk factors of adverse outcomes among women with COVID-19 in the pregnancy and postpartum period: a sequential, prospective meta-analysis

OBJECTIVE

This sequential, prospective meta-analysis sought to identify risk factors among pregnant and postpartum women with COVID-19 for adverse outcomes related to disease severity, maternal morbidities, neonatal mortality and morbidity, and adverse birth outcomes.

DATA SOURCES

We prospectively invited study investigators to join the sequential, prospective meta-analysis via professional research networks beginning in March 2020.

STUDY ELIGIBILITY CRITERIA

Eligible studies included those recruiting at least 25 consecutive cases of COVID-19 in pregnancy within a defined catchment area.

METHODS

We included individual patient data from 21 participating studies. Data quality was assessed, and harmonized variables for risk factors and outcomes were constructed. Duplicate cases were removed. Pooled estimates for the absolute and relative risk of adverse outcomes comparing those with and without each risk factor were generated using a 2-stage meta-analysis.

RESULTS

We collected data from 33 countries and territories, including 21,977 cases of SARS-CoV-2 infection in pregnancy or postpartum. We found that women with comorbidities (preexisting diabetes mellitus, hypertension, cardiovascular disease) vs those without were at higher risk for COVID-19 severity and adverse pregnancy outcomes (fetal death, preterm birth, low birthweight). Participants with COVID-19 and HIV were 1.74 times (95% confidence interval, 1.12-2.71) more likely to be admitted to the intensive care unit. Pregnant women who were underweight before pregnancy were at higher risk of intensive care unit admission (relative risk, 5.53; 95% confidence interval, 2.27-13.44), ventilation (relative risk, 9.36; 95% confidence interval, 3.87-22.63), and pregnancy-related death (relative risk, 14.10; 95% confidence interval, 2.83-70.36). Prepregnancy obesity was also a risk factor for severe COVID-19 outcomes including intensive care unit admission (relative risk, 1.81; 95% confidence interval, 1.26-2.60), ventilation (relative risk, 2.05; 95% confidence interval, 1.20-3.51), any critical care (relative risk, 1.89; 95% confidence interval, 1.28-2.77), and pneumonia (relative risk, 1.66; 95% confidence interval, 1.18-2.33). Anemic pregnant women with COVID-19 also had increased risk of intensive care unit admission (relative risk, 1.63; 95% confidence interval, 1.25-2.11) and death (relative risk, 2.36; 95% confidence interval, 1.15-4.81).

CONCLUSION

We found that pregnant women with comorbidities including diabetes mellitus, hypertension, and cardiovascular disease were at increased risk for severe COVID-19-related outcomes, maternal morbidities, and adverse birth outcomes. We also identified several less commonly known risk factors, including HIV infection, prepregnancy underweight, and anemia. Although pregnant women are already considered a high-risk population, special priority for prevention and treatment should be given to pregnant women with these additional risk factors.

Ferritin screening and Iron treatment for maternal anemia and fetal growth restriction prevention - A multicenter randomized controlled trial (FAIR Study)

Background

Non-anemic iron deficiency precedes iron deficiency anaemia and has an estimated prevalence of 1-2 billion worldwide. Few studies have comprehensively researched the idea of treating non-anemic iron deficiency (NAID) with iron to improve the outcome of the mother and the offspring.

Methods and Analysis

FAIR will be a multicenter randomized controlled trial that will be conducted in multiple clinical academic obstetrics units in Lahore (including Services Institute of Medical Sciences, Lahore, Allama Iqbal Medical College, Lahore and Fatima Jinnah Medical University). Pregnant women at gestational age <20 weeks with hemoglobin 11-13 g/L and ferritin below the threshold (<30 ng/ml) will be invited to take part in the study. Randomization will be done by computer based generated random numbers. One group (usual care or oral group) will be offered routine care prophylactic dose of oral iron (30-45 mg/day) and the other group (intervention arm or IV group) will be offered therapeutic dose of IV iron (dose calculated by Ganzoni formula) in addition to usual care. All patients will be followed up till delivery. Primary maternal outcome will be hemoglobin at 36 weeks' gestation. Secondary outcomes are fetal birthweight or small for gestational age, preterm birth, preeclampsia, multidimensional fatigue inventory, breast feeding initiation, blood transfusion, and fetal cord ferritin and hemoglobin.

Discussion

The study will generate evidence as to whether screening serum ferritin in non-anemic pregnant women and replenishing their iron stores will likely reduce the rate of predelivery anemia in pregnant women, improve birthweight and preventing perinatal complications.

Roles and responsibilities

Tayyiba Wasim is principal Investigator and other members of data management team are Natasha Bushra, Shamsa Humayoun, Khalid Saeed Khan, Fatima Shehbaz, Saba Rasool, Anam Riaz and Sonia Irshad. Principal investigator will assume the full responsibility of Fair trial including training of research assistants, administration of informed consent and protecting participants confidentiality. Data management team will help in the management, development and execution of trial. Khadija Irfan Khawaja is the operational lead for fair trial´s technology team comprising of Aziz Fatima and Zubia Zafar, responsible for gathering requirements from study teams and supporting the operational implementation of technology to drive the collection of high-quality study data. Protocol contributors are Gynae unit I of Services Institute of Medical Sciences/ Services hospital, Lahore, Gynae Unit II of Allama Iqbal Medical College/ Jinnah hospital, Lahore and Gynae unit 1 of Fatima Jinnah Medical College/ Sir Ganga Ram hospital, Lahore. These coordinating centres will recruit patients (sample size=600) and will discuss their progress in trial management meetings quarterly.

Steering committee

has an independent chair Prof Samia Malik, one expert member Prof Faiza Bashir and Ms Neelam to represent patients, public and consumers. Trial steering committee with independent chair and member with a patient representative will oversee the study. Chair of steering committee has the authority to stop the trial whenever needed in case of positive or negative results. Steering committee meetings will be held on annual basis.

Independent Data monitoring committee

comprises of Dr. Shehnoor Azhar as chair and Prof Ejaz Hussain and Dr. Shehla Javed Akram as members. Data monitoring committee will assess the progress, data safety and if needed critical efficacy points of the clinical study and will show their results quarterly in data interim meetings. The committee will focus on integrity of the whole process and compliance of all sites with all aspects of the protocol. It will perform confidential interim analyses quarterly, which may be used to determine if an effect is observed and if the study should continue to its planned sample size. Data monitoring committee will report to the Chair of the steering committee.

A Randomised Controlled Trial to Compare Injection Ferric Carboxymaltose and Oral Iron in Treating Iron Deficiency Anemia During Pregnancy

Introduction

Iron deficiency anemia (IDA) in pregnancy has a prevalence as high as 40-60% in different countries of the world. Oral iron is used to treat his commonest medical disorder in pregnancy. Ferrous sulphate is associated with considerable side effects. Ferric carboxymaltose (FCM) is a newer iron preparation which allows for single and higher dose (up to 1000 mg) of IV iron infusion. This study was conducted to compare the efficacy of FCM and FS in treating IDA during pregnancy.

Methods

A randomised control trial was done at a tertiary care centres involving 362 women (181 women each in FS and FCM group). The pregnant anemic women with IDA were enrolled between 18 and 34 weeks of pregnancy. They were given 1000 mg of FCM iv as single dose or were given FS tablets twice daily (120 mg iron daily). The data were collected for rise in the Hb and serum ferritin over a period of 6 weeks.

Results

Nine and 18 patients were lost to follow-up in the FCM and FS group, respectively. The data were analysed as per protocol analysis. FCM group women showed 2.6 gm% rise in Hb compared to 1.7 gm% of FS group. One hundred and sixty-six out of 172 women in FS group achieved anemia correction at 6 weeks. No difference was observed in the neonatal outcome. No major side effects were observed in the either group.

Conclusion

In our study, FCM was more effective than oral FS in increasing Hb in women with IDA during pregnancy. This clinical benefit with FCM was achieved without the concerns for safety and tolerability of the drug.

Testing equivalence of two doses of intravenous iron to treat iron deficiency in pregnancy: A randomised controlled trial

OBJECTIVE

To test equivalence of two doses of intravenous iron (ferric carboxymaltose) in pregnancy.

DESIGN

Parallel, two-arm equivalence randomised controlled trial with an equivalence margin of 5%.

SETTING

Single centre in Australia.

POPULATION

278 pregnant women with iron deficiency.

METHODS

Participants received either 500 mg (n=152) or 1000mg (n=126) of intravenous ferric carboxymaltose in the second or third trimester.

MAIN OUTCOME MEASURES

The proportion of participants requiring additional intravenous iron (500mg) to achieve and maintain ferritin >30ug/L (diagnostic threshold for iron deficiency) at 4 weeks post-infusion, and at 6 weeks, and 3-, 6- and 12-months postpartum. Secondary endpoints included repeat infusion rate, iron status, birth, and safety outcomes.

RESULTS

The two doses were not equivalent within a 5% margin at any timepoint. At 4 weeks post infusion, 26/73 (36%) participants required a repeat infusion in the 500 mg group compared with 5/67 (8%) in the 1000 mg group (difference in proportions, 0.283 95% confidence interval (0.177, 0.389)). Overall, participants in the 500 mg arm received twice the repeat infusion rate (0.81 (SD= 0.824 vs 0.40 (SD= 0.69), rate ratio 2.05, 95% CI (1.45, 2.91)).

CONCLUSIONS

Administration of 1000 mg ferric carboxymaltose in pregnancy maintains iron stores and reduces the need for repeat infusions. A 500 mg dose requires ongoing monitoring to ensure adequate iron stores are reached and sustained.

Maternal iron deficiency anaemia in pregnancy: Lessons from a national audit

We describe the management and the prevalence of iron deficiency anaemia (IDA) during pregnancy by comparison to standards. A cross-sectional national cohort study of women who had given birth six weeks prior to data collection was conducted at maternity units in the UK and Ireland. Participating centres collected data from 10 consecutive pregnant women. Analysis was descriptive to define the prevalence of IDA in pregnancy and the puerperium, and to compare the outcomes in women who had IDA with women who did not have anaemia anytime during pregnancy. Eighty-six maternity units contributed data on 860 pregnancies and births. The overall prevalence of IDA during pregnancy was 30.4% and in the puerperium 20%. Anaemic women were more likely to be from ethnic minorities, odds ratio 2.23 (1.50, 3.32). Adherence to national guidance was suboptimal, and the prevalence of anaemia in pregnancy remains very high. There is pressing need to explore barriers to early identification and effective management of iron deficiency. IDA should be considered a major public health problem in the UK.

Anemia and adverse outcomes in pregnancy: subgroup analysis of the CLIP cluster-randomized trial in India

Background

Iron-deficiency anemia is a known risk factor for several adverse perinatal outcomes, but data on its impact on specific maternal morbidities is less robust. Further, information on associations between anemia in early pregnancy and subsequent outcomes are understudied.

Methods

The study population was derived from the Community Level Interventions for Pre-eclampsia (CLIP) trial in Karnataka State, India (NCT01911494). Included were women who were enrolled in either trial arm, delivered by trial end date, and had a baseline measure of hemoglobin (Hb). Anemia was classified by WHO standards into four groups: none (Hb ≥ 11 g/dL), mild (10.0 g/dL ≤ Hb < 11.0 g/dL), moderate (7.0 g/dL ≤ Hb < 10.0 g/dL) and severe (Hb < 7.0 g/dL). Targeted maximum likelihood estimation was used to estimate confounder-adjusted associations between anemia and a composite (and its components) of adverse maternal outcomes, including pregnancy hypertension. E-values were calculated to assess robustness to unmeasured confounding.

Results

Of 11,370 women included, 10,066 (88.5%) had anemia, that was mild (3690, 32.5%), moderate (6023, 53.0%), or severe (68, 0.6%). Almost all women (> 99%) reported taking iron supplements during pregnancy. Blood transfusions was more often administered to those with anemia that was mild (risk ratio [RR] 2.16, 95% confidence interval [CI] 1.31–3.56), moderate (RR 2.37, 95% CI 1.56–3.59), and severe (RR 5.70, 95% CI 3.00–10.85). No significant association was evident between anemia severity and haemorrhage (antepartum or postpartum) or sepsis, but there was a U-shaped association between anemia severity and pregnancy hypertension and pre-eclampsia specifically, with the lowest risk seen among those with mild or moderate anemia.

Conclusion

In Karnataka State, India, current management strategies for mild-moderate anemia in early pregnancy are associated with similar rates of adverse maternal or perinatal outcomes, and a lower risk of pregnancy hypertension and preeclampsia, compared with no anemia in early pregnancy. Future research should focus on risk mitigation for women with severe anemia, and the potential effect of iron supplementation for women with normal Hb in early pregnancy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-04714-y.

Altered Offspring Immunity in Maternal Parasitic Infections

Maternal infection during pregnancy is known to alter the development and function of offspring's immune system, leading to inappropriate immune responses to common childhood infections and immunizations. Although this is an expanding field, maternal parasitic infections remain understudied. Millions of women of reproductive age are currently at risk for parasitic infection, whereas many pregnant, chronically infected women are excluded from mass drug administration due partially to a lack of resources, as well as fear of unknown adverse fetal developmental outcomes. In areas endemic for multiple parasitic infections, such as sub-Saharan Africa, there are increased rates of morbidity and mortality for various infections during early childhood in comparison with nonendemic areas. Despite evidence supporting similar immunomodulatory effects between various parasite species, there is no clear mechanistic understanding of how maternal infection reprograms offspring immunity. This brief review will compare the effects of selected maternal parasitic infections on offspring immunity.

Money and my mind: Maternal cash transfers and mental health

This paper documents important mental health spillovers in the context of a program that offered pregnant women modest cash incentives to use pre- and perinatal health care services. Program participation was randomized and the payments were made after the birth of the child (and after the completion of an endline mental health assessment). I present causal evidence that the program led to improvements in mothers' mental health. The effect size ranges from a 1-3 percentage point reduction in postpartum depression measured using the Edinburgh Postnatal Depression Scale. I present suggestive evidence that these beneficial effects on mental health may be related to program-induced improvements in child health. These results provide novel evidence that programs designed to improve birth outcomes may generate unanticipated spillover effects on mental health.

Iron deficiency anaemia in pregnancy: A contemporary review

Iron deficiency anaemia is a global health problem, which particularly affects pregnant women. Iron deficiency anaemia during pregnancy is associated with increased maternal and perinatal morbidity and mortality. Maternal iron deficiency may also be associated with neurocognitive deficits in infants. Iron requirements increase during pregnancy and are influenced by hepcidin, the master regulator of iron homeostasis. The enduring global burden of maternal anaemia suggests that currently employed iron supplementation strategies are suboptimal. Recent developments in our understanding of systemic and placental iron homeostasis may improve therapeutic effectiveness by altering the dose and frequency of oral iron. Intravenous iron appears to be a safe treatment to correct maternal anaemia rapidly but research on patient-centred outcomes and cost-effectiveness is needed. Future trials should be adequately powered to assess outcomes relevant to pregnant women.

Hemoglobin Level and Associated Factors among Pregnant Women in Rural Southwest Ethiopia

Background

Anemia is a situation in which the number and size of red blood cells, or the concentration of hemoglobin, fall below established cut-off values. Low hemoglobin level during pregnancy favors the alteration of placental angiogenesis and resulted in restricting the availability of nutrients to the fetus and consequently causing fetal growth retardation and low weight at birth. This study is aimed at assessing the hemoglobin level and associated factors among pregnant women in rural communities of Jimma zone, Southwest Ethiopia.

Methods

A community-based cross-sectional study design was carried out among 367 pregnant women from June 1 to 30, 2020. Systematic random sampling was used to select study subjects. Hemoglobin level was measured by using HemoCue HB 301. An interviewer-administered structured questionnaire was used to collect the data. Descriptive statistics were used to describe the study subjects. A multivariable linear regression model was employed after the linearity, normality, multicollinearity, and homoscedasticity assumptions were checked. The unstandardized beta (β) coefficient along with a 95% confidence interval was computed to estimate the association between explanatory and dependant variables. Statistical significance was declared at P value < 0.05.

Results

The mean (± SD) hemoglobin level of the respondents was 12.66 (±1.44) g/dl. The overall magnitude of anemia (hemoglobin level < 11 g/dl) among pregnant women was found to be 85 [23.16%, (95% CI: 18.3%-27.5%)]. Meal frequency [β = 0.40, (95% CI: 0.12, 0.69), P = 0.005], interpregnancy interval [β = 0.08, (95% CI: 0.02, 0.15), P = 0.007], mid-upper arm circumference measurement [β = 0.13, (95% CI: 0.07, 0.20), P ≤ 0.001], own fruits/vegetable [β = 0.55, (95% CI: 0.79, 0.31), P ≤ 0.001], coffee consumption [β = −1.00, (95% CI: -1.31, -0.68), P ≤ 0.001], and having history of still birth [β = −0.63, (95% CI: -1.06, -0.20), P = 0.004] were significantly associated with the hemoglobin level of pregnant women.

Conclusions

Anemia was identified to be a moderate public health problem in the study area. Therefore, nutritional counseling should focus on the necessity of at least one extra meal, promotion of fruits/vegetable consumption, and improving the nutritional status of the women during antenatal care follow-up. Moreover, early screening and management of women with a history of stillbirth for anemia are also essential.

The effect of iron deficiency and anaemia on women's health

Iron deficiency and anaemia are global health problems and major causes of morbidity in women. Current definitions of anaemia in women are historic and have been challenged by recent data from observational studies. Menstrual loss, abnormal uterine bleeding and pregnancy put women at risk of developing iron deficiency which can result in severe fatigue, reduced exercise capacity and poor work performance. Iron deficiency and anaemia during pregnancy are associated with adverse maternal and fetal outcomes, including neurocognitive deficits in children born to iron-deficient mothers. Both iron deficiency and anaemia are common in women undergoing surgery but their association with poor outcomes remains uncertain. The enduring burden of iron deficiency and anaemia in women suggests that current strategies for recognition, prevention and treatment are limited in their utility. Improvements in our understanding of iron homeostasis and the development of new iron preparations, which are better absorbed with fewer side-effects, may improve therapeutic effectiveness of oral iron. Intravenous iron is efficacious for correcting anaemia rapidly but high-quality data on patient-centred outcomes and cost-effectiveness are currently lacking. Many recommendations for the treatment of iron deficiency and anaemia in national guidelines are not supported by high-quality evidence. There is a need for robust epidemiological data and well-designed clinical trials. The latter will require collaborative working between researchers and patients to design studies in ways that incorporate patients' perspectives on the research process and target outcomes that matter to them.

No. 394-Stillbirth Investigation

OBJECTIVES

To provide an investigation protocol to help health care providers determine the cause of a fetal death.

OPTIONS

Consideration has been given to protocols for the investigation of fetal death that are currently available in Canada and in other countries.

OUTCOMES

Identification of possible causes of stillbirth and their relationship to future pregnancies.

EVIDENCE

Articles related to the etiology of fetal death were identified in a search of PubMed (June 2006 to September 2018), the Cochrane Library, and investigation protocols from the American College of Obstetricians and Gynecologists, the International Stillbirth Alliance Collaborative for Improving Classification of Perinatal Deaths, the Royal College of Obstetricians and Gynaecologists, the Queensland clinical guidelines, and the Reproductive Care Program of Nova Scotia.

BENEFITS

To provide better advice for women regarding possible causes of fetal death and implications for future pregnancies.

VALIDATION

The evidence obtained was reviewed and evaluated by the Maternal-Fetal Medicine Committee and the Clinical Practice Obstetrics Committee of the Society of Obstetricians and Gynaecologists of Canada. The level of evidence and quality of the recommendation made was described using the Evaluation of Evidence criteria of the Canadian Task Force on Preventive Health Care.

RECOMMENDATIONS

The use of intravenous iron in pregnancy: for whom and when? A survey of Australian and New Zealand obstetricians

BACKGROUND

Iron deficiency anaemia in pregnancy (IDAP) affects 11-18% of Australian pregnancies and is associated with adverse perinatal outcomes. National prescribing data suggests the use of intravenous iron in pregnancy is increasingly common. This study aimed to: 1) Establish the current patterns of intravenous iron use by Fellows of the Royal Australian and New Zealand College of Obstetricians (FRANZCOG) when treating iron deficiency and IDAP including immediately postpartum and; 2) Assess FRANZCOG opinions regarding potential trial of intravenous iron for first-line treatment of IDAP.

METHODS

An online survey of RANZCOG Fellows practicing obstetrics was distributed in September 2018. Results were analysed descriptively and responses compared by clinician demographics using Chi-squared testing.

RESULTS

Of 484 respondents (21% of FRANZCOG), 457 were currently practicing obstetrics. Most prescribed intravenous iron in pregnancy (96%) and/or postpartum (85%). Most intravenous iron was prescribed for IDAP (98%) rather than iron deficiency without anaemia (53%), and for IDAP most commonly second-line to failed oral iron supplementation and first-line in special circumstances (59%). Intravenous iron prescribing was associated with shorter time since FRANZCOG completion (p = 0.01), public hospital practice (p = 0.008) and higher hospital birth numbers (p = 0.01). Most respondents (90%) would consider a randomised controlled trial of first-line intravenous iron for IDAP, although views on appropriate thresholds differed.

CONCLUSIONS

Almost all respondents prescribed intravenous iron for IDAP, and while mostly used for second-line treatment over half sometimes used it first-line. With accelerating intravenous iron use, further research is required into its optimal use in pregnancy, recognizing important clinical outcomes and cost effectiveness.

Preconception Hb concentration with risk of spontaneous abortion: a population-based cohort study in over 3·9 million women across rural China

OBJECTIVE

Evidence on the relationship between maternal Hb concentration and spontaneous abortion (SA) risk is limited and conflicting. The purpose of the study was to evaluate whether maternal preconception anaemia or high Hb concentration is associated with risk of SA.

DESIGN

A population-based cohort study established between 2013 and 2017.

SETTINGS

Local maternal and child care service centres in each county.

PARTICIPANTS

In total, 3 971 428 women aged 20-49 years, who participated in National Free Pre-Pregnancy Checkups Project from 2013 to 2016 and successfully got pregnant before 2017 in rural China.

RESULTS

A total of 101 700 (2·56 %) women were recorded having SA, with highest SA rate in women with severe anaemia (4·58 %). Compared with women with Hb of 110-149 g/l, the multivariable-adjusted OR for SA was 1·52 (95 % CI: 1·25, 1·86) for women with Hb < 70 g/l, 0·92 (0·84, 1·01) for 70-99 g/l, 0·80 (0·77, 0·83) for 100-109 g/l, 1·11 (1·08, 1·15) for 150-159 g/l, 1·12 (1·04, 1·20) for 160-169 g/l and 1·02 (0·93, 1·12) for ≥ 170 g/l, respectively. An approximate U-shaped curve for the risk of SA with Hb concentrations was observed when Hb concentrations less than 145 g/l, above which the association plateaued (Pnon-linear < 0·001).

CONCLUSIONS

Severe anaemia and high Hb concentration before pregnancy were associated with an increased risk of SA. Women with mild anaemia prior to pregnancy had lower risk of SA. Underlying mechanisms need to be further studied.

Healthcare at the Beginning of Life and Child Survival: Evidence from a Cash Transfer Experiment in Nigeria

Households in poor countries are encouraged (and sometimes coerced) to increase investments in formal health care services during pregnancy and childbirth. Is this good policy? The answer to a large extent depends on its effects on child welfare. We study the effects of a cash transfer program in Nigeria in which households were offered a payment of $14 conditioned on uptake of health services. We show that the transfer led to a large increase in uptake and a substantial increase in child survival driven by a decrease in in-utero child deaths. We present evidence suggesting that the key driver is prenatal health investments.

Nutritional and perinatal outcomes of pregnant women with a history of bariatric surgery: a case series from a UK centre

BACKGROUND

Women with obesity who become pregnant after bariatric surgery have a reduced risk of several obstetric complications; however, limited data exist from the UK population. The present study aimed to characterise a case series of women who attended a medical antenatal clinic for pregnancy following bariatric surgery.

METHODS

Routine clinical information was collected retrospectively from the medical notes of women who had bariatric surgery and subsequently delivered between January 2012 and November 2018. All were seen in the medical antenatal clinic at Musgrove Park Hospital, Taunton.

RESULTS

Data were available for 46 pregnancies. Of these, 27.9% conceived in the first year after surgery. At 9 weeks of gestation, 13.3%, 28.9%, 33.3% and 24.4% were in the healthy, overweight, obese or severely obese category, respectively. Mean (SD) gestational weight gain was 11.9 (6.9) kg, with 54.1% gaining excess weight. Less than half (39.1%) of women were taking the recommended dose of 5 mg of folic acid when first seen. Some 56.1% and 64.6% had suboptimal iron or vitamin D statuses, respectively. Following advice from the clinic, a greater proportion of women took suitable micronutrient supplements. Subsequently, 93% of babies were born at full term, of whom 88% were of healthy weight.

CONCLUSIONS

Despite the nutritional risks associated with bariatric surgery and the high prevalence of obesity during pregnancy, perinatal outcomes were generally positive, with low rates of infants born preterm or low birth weight. Nutritional supplementation practices and iron status improved with input from a specialist team, underlying the importance of individualised input in this population.

The burden of anaemia among displaced women and children in refugee settings worldwide, 2013-2016

Introduction

Displaced persons have a unique risk for developing anaemia due to often limited diets, overcrowding, new infections and inadequate sanitation and hygiene. The lack of anaemia prevalence estimates among the displaced inhibit global planning for anaemia reduction.

Methods

We analysed population representative, cross-sectional nutrition surveys from 2013 to 2016 conducted by the United Nations High Commissioner for Refugees and partner agencies. Included surveys measured haemoglobin concentration among children 6–59 months, non-pregnant women 15–49 years, or both groups. For each survey, we calculated mean haemoglobin and prevalence of total anaemia (<110 g/L in children, <120 g/L in women), and classified public health severity following WHO guidelines. Pearson correlations between indicators from women and children surveys were calculated where both subpopulations were measured.

Results

Analysis included 196 surveys among children and 184 surveys among women from 121 unique refugee settings in 24 countries. The median prevalence of total anaemia in children and women was 44% and 28%, respectively. Sixty-one per cent of child surveys indicated a problem of severe public health importance compared with 25% of surveys in women. The prevalence of total anaemia in children and women was strongly correlated (ρ=0.80). Median prevalence of total anaemia was approximately 55% greater and mean haemoglobin was 6 g/L lower among children age 6–23 months compared with children 24–59 months. West and Central Africa region had the highest median prevalence of anaemia both in women and children.

Conclusion

While the burden of anaemia is high among the displaced, it mirrors that of the general population. Haemoglobin should continue to be measured in nutrition surveys in refugee settings. Sustained, multisectoral efforts to reduce anaemia are needed, with specific focus on children under 2 years of age and refugee settings in the West and Central Africa region.

The change in haemoglobin concentration between the first and third trimesters of pregnancy: a population study

Background

The physiological fall in haemoglobin concentration from the 1st to the 3rd trimester of pregnancy is often quoted as 5 g/L. However, other studies have suggested varying levels of fall between 8 and 13 g/L. We evaluated the change in haemoglobin concentration between the 1st and 3rd trimesters of pregnancy in a multi-ethnic population of pregnant women.

Methods

A retrospective cohort analysis of 7054 women with singleton pregnancies, giving birth during 2013–15 in a single urban maternity unit in England.

We calculated the changes in haemoglobin concentration from 1st to 3rd trimester using the first trimester haemoglobin as the reference point. The population was stratified into sub-groups to explore any differences that existed within the population.

Results

In general the fall in haemoglobin concentration was in the order of 14 g/L or 11% of the first trimester value. This fall was consistent for the majority of sub-groups of the population. The fall was lower (7.7%) in the most deprived section of the population, IMD1, but it increased to 11.7% when we restricted that sub-group to pregnant women without health problems during the index pregnancy. Conversely, there was an increase in haemoglobin of 10.2% in women whose first trimester haemoglobin concentration was in the lowest 5% of the total study population. The population fall in haemoglobin was 10.2 g/L (7.8%), after excluding cases above the 95th and below the 5th centiles, and women with a medical and/or obstetric disorder during the pregnancy.

Conclusion

The fall in haemoglobin during pregnancy is in the order of 14 g/L or 11% of the first trimester level. This is 2 to 3 times higher than suggested by some guidelines and higher than previously published work. The results challenge the current accepted thresholds for practice, and have broader implications for diagnosis and managment of antenatal anaemia.

Tweetable abstract

Fall in haemoglobin across pregnancy is around 14 g/L (11%) and significantly higher than previously stated in the pregnant population. This poses questions over currently accepted thresholds for anaemia in pregnancy.

Maternal hemoglobin concentrations across pregnancy and maternal and child health: a systematic review and meta-analysis

Maternal anemia is a well‐recognized global health problem; however, there remain questions on specific hemoglobin (Hb) thresholds that predict health risk or protection for mother and child. We conducted a systematic review and meta‐analysis to examine the associations of maternal Hb concentrations with a range of maternal and infant health outcomes, accounting for the timing of measurement (preconception, and first, second, and third trimesters), etiology of anemia, and cutoff category. The systematic review included 272 studies and the meta‐analysis included 95 studies. Low maternal Hb (<110 g/L) was associated with poor birth outcomes (low birth weight, preterm birth, small‐for‐gestational‐age (SGA), stillbirth, and perinatal and neonatal mortality) and adverse maternal outcomes (postpartum hemorrhage, preeclampsia, and blood transfusion). High maternal Hb (>130 g/L) was associated with increased odds of SGA, stillbirth, preeclampsia, and gestational diabetes. Relationships varied by the timing of measurement and cutoff category (stronger associations with lower cutoffs); limited data were available on anemia etiology. There were insufficient data for other maternal outcomes and long‐term child health outcomes. Current data are insufficient for determining if revisions to current Hb cutoffs are required. Pooled high‐quality individual‐level data analyses, as well as prospective cohort studies, would be valuable to inform the reevaluation of Hb cutoffs.

Maternal anaemia and maternal, fetal, and neonatal outcomes in a prospective cohort study in India and Pakistan

OBJECTIVE

To describe the association of maternal anaemia with maternal, fetal, and neonatal outcomes.

DESIGN

Prospective cohort study.

SETTING

Rural India and Pakistan.

POPULATION

Pregnant women residing in the study catchment area.

METHODS

We performed an analysis of a prospective pregnancy registry in which haemoglobin is commonly obtained as well as maternal, fetal, and neonatal outcomes for 42 days post-delivery. Women 40 years or older who delivered before 20 weeks or had a haemoglobin level of <3.0 g/dl were excluded. Our primary exposure was maternal anaemia, which was categorised in keeping with World Health Organization criteria based on a normal (≥11 g/dl), mild (>10-10.9 g/dl), moderate (7-9.9 g/dl) or severe (<7 g/dl). haemoglobin level. The primary maternal outcome was maternal death, the primary fetal outcome was stillbirth, and the primary neonatal outcome was neonatal mortality <28 days.

RESULTS

A total of 92 247 deliveries and 93 107 infants were included, of which 87.8% were born to mothers who were anaemic (mild 37.9%, moderate 49.1%, and severe 0.7%). Maternal mortality (number per 100 000) was not associated with anaemia: normal 124, mild 106, moderate 135, and severe 325 (P = 0.64). Fetal and neonatal mortality was associated with severe anaemia: stillbirth rate (n/1000)-normal 27.7, mild 25.8, moderate 30.1, and severe 90.9; P < 0.0001; 28-day neonatal mortality (n/1000)-normal 24.7, mild 22.9, moderate 28.1, and severe 72.6 (P < 0.0001). Severe maternal anaemia was also associated with low birthweight (<2500 and <1500 g), preterm birth, and postpartum haemorrhage.

CONCLUSION

Severe maternal anaemia is associated with higher risks of poor maternal, fetal, and neonatal outcomes but other degrees of anaemia are not. Interventions directed at preventing severe anaemia in pregnant women should be considered.

TWEETABLE ABSTRACT

Severe maternal anaemia is associated with adverse fetal and neonatal outcomes in low/middle-income countries.

Maternal anemia and pediatric neurological morbidity in the offspring - Results from a population based cohort study

OBJECTIVE

Maternal anemia (Hemoglobin, <11 mg/dl) has been shown to affect fetal growth and pregnancy outcome. We aimed to study a possible association between maternal anemia and the risk for neurological morbidity in the offspring, during a follow-up period of up to 18 years.

STUDY DESIGN

A population-based cohort analysis was performed at the Soroka University Medical Center (SUMC), a single regional tertiary center comparing total and specific subtypes of neurological morbidities associated with hospitalizations among children stratified by three maternal post-partum hemoglobin categories: ≥11 mg/dl (no anemia); 11.0 mg/dl > Hb ≥ 7 mg/dl (mild-to-moderate anemia) and <7 mg/dl (severe anemia). Data on pregnancy course and outcome, and later offspring hospitalizations, were compared between the three study groups. All singleton deliveries between the years 1991-2014 were included in the analysis, and congenital malformations were excluded. A Kaplan-Meier survival curve was used to compare cumulative hospitalization incidence based on maternal anemia status, and a Weibull survival multivariable hazard model was constructed to adjust for confounding variables.

RESULTS

The study population included 217,358 deliveries of which 50.6% were in mothers who were not anemic, 49.0% in mothers with moderate anemia and 0.4% in mothers with severe anemia. During the follow up period (0-18 years, median 10.22 years), 2.1% of offspring were hospitalized with a neurological diagnoses. Neurological hospitalization incidence decreased from 2.95/1000 person years, in the severe anemia group, to 2.32/1000 person years and 2.01/1000 person years, among the mild-to-moderate and no anemia groups, respectively (p = 0.007). The association between maternal anemia and offspring long-term pediatric neurological morbidity remained significant in a Weibull hazards model controlled for gestational age, delivery mode, SGA and insufficient prenatal care (adjusted HR 1.55; 1.05-2.31 and adjusted HR 1.13; 1.06-1.20; among the severe and mild-to-moderate anemia, vs. no anemia, respectively).

CONCLUSION

Children born to anemic mothers are at an increased risk for pediatric neurological-related hospitalizations.

Pathways of association between maternal haemoglobin and stillbirth: path-analysis of maternity data from two hospitals in England

OBJECTIVE

To investigate the mechanisms that link maternal haemoglobin concentration with stillbirth.

DESIGN

A retrospective cohort analysis using anonymised maternity data from two hospitals in England.

SETTING

The Royal Wolverhampton NHS Trust and Guy's and St Thomas' NHS Foundation Trust.

STUDY POPULATION

12 636 women with singleton pregnancies ≥24 weeks of gestation giving birth in the two hospitals during 2013-2015.

METHOD

A conceptual framework of hypothesised pathways through birth weight-for-gestational age and maternal infection including potential confounders and other risk factors was developed and examined using path-analysis. Path-analysis was performed by fitting a set of regression equations using weighted least squares adjusted for mean and variance. Goodness-of-fit indices were estimated.

MAIN OUTCOME MEASURES

Coefficient of association (β) for relationship between each parameter, and direct, indirect and total effects via the postulated pathways.

RESULTS

The path-model showed a significant adjusted indirect negative effect of maternal haemoglobin on stillbirth mediated via birth weight-for-gestational age (standardised estimate (SE)=-0.01; 95% CI=-0.01 to -0.001; P=0.028). The effect through maternal infection was not significant at P<0.05 (SE=0.001; 95% CI=-0.004 to 0.01; P=0.610). There was a residual direct negative effect of maternal haemoglobin on stillbirth (SE=-0.12; 95% CI -0.23 to -0.02; P=0.020) after accounting for the two pathways. Total indirect SE=-0.004; 95% CI -0.01 to 0.003; P=0.267; total direct and indirect SE=-0.13; 95% CI -0.23 to -0.02; P=0.016. The goodness-of-fit indices showed a good fit between the model and the data.

CONCLUSION

While some of the influence on risk of stillbirth acts through low birth weight-for-gestational age, the majority does not. Several new mechanisms have been suggested for how haemoglobin may be exerting its influence on the risk of stillbirth possibly involving genetic, epigenetic and/or alternative obstetric and nutritional pathologies, but much more research is needed.