Reviewing the past to inform the future: an 8-year review of severe maternal morbidity.

BACKGROUND: Maternal morbidity is becoming a key indicator used to compare health systems in the developed world and also to inform clinical practice. OBJECTIVE: This study aimed to evaluate a single center experience of severe maternal morbidity over an 8-year period. STUDY DESIGN: We conducted a retrospective review of all cases of severe maternal morbidity from 2012 to 2019 at a tertiary level maternity hospital in the Republic of Ireland with approximately 9000 births per year. We examined maternal demographics, pregnancy characteristics, and care requirements. Descriptive statistics were used throughout. RESULTS: There were 81,504 maternity cases and 67,894 births during the study period. A total of 504 women had a severe maternal morbidity, giving a rate of 6.1 per 1000 maternity cases overall, peaking in 2017 at 8.8 per 1000. When individual severe maternal morbidity events were evaluated, the rate increased from 6 per 1000 to 9 per 1000 over the 8-year period. There were no differences in maternal age, nationality, or body mass index during the years analyzed. Interestingly, 8.9% (n=45) were multiple gestations, and nearly one-fifth (19.4%; n=98) required escalation of care to a general hospital; of these, 14.0% (n=74) required cardiac or intensive care management. The majority of morbidities manifested in the third trimester (58.7%; n=296) or postnatally (42.8%, n=216). The most common severe maternal morbidities were hypertensive disorders of pregnancy, followed by postpartum hemorrhage and sepsis (45.0%, 44.2%, and 12.7%, respectively). CONCLUSION: We provide a longitudinal overview of severe maternal morbidity in a large maternity hospital that replicates other international findings. This information can be used for healthcare comparisons and for resource planning and allocation.

GWAS meta-analysis of intrahepatic cholestasis of pregnancy implicates multiple hepatic genes and regulatory elements.

Intrahepatic cholestasis of pregnancy (ICP) is a pregnancy-specific liver disorder affecting 0.5-2% of pregnancies. The majority of cases present in the third trimester with pruritus, elevated serum bile acids and abnormal serum liver tests. ICP is associated with an increased risk of adverse outcomes, including spontaneous preterm birth and stillbirth. Whilst rare mutations affecting hepatobiliary transporters contribute to the aetiology of ICP, the role of common genetic variation in ICP has not been systematically characterised to date. Here, we perform genome-wide association studies (GWAS) and meta-analyses for ICP across three studies including 1138 cases and 153,642 controls. Eleven loci achieve genome-wide significance and have been further investigated and fine-mapped using functional genomics approaches. Our results pinpoint common sequence variation in liver-enriched genes and liver-specific cis-regulatory elements as contributing mechanisms to ICP susceptibility.

A survey of perceived traumatic birth experiences in an Irish maternity sample - prevalence, risk factors and follow up.

OBJECTIVES: To establish the prevalence and correlates of a subjectively traumatic birth experience in an Irish maternity sample. DESIGN: A questionnaire routinely provided to all women prior to hospital discharge post-birth was amended for data collection for this study. Two additional questions seeking information about women's perceptions of their birth were added and analysed. Women who described their birth as traumatic and agreed to follow-up, received a City Birth Trauma Scale (Ayers et al., 2018) at subsequent follow-up (6 to 12 weeks postpartum). Demographic, obstetric, neonatal variables and factors associated with birth trauma were collected from electronic maternity records retrospectively. SETTING: A postnatal ward in an Irish maternity hospital which provides postnatal care for public maternity patients. PARTICIPANTS: Postpartum women (N=1154) between 1 and 5 days postpartum. MEASUREMENTS & FINDINGS: Participants completed the Edinburgh Postnatal Depression Scale (EPDS) (Cox et al., 1987) with two additional questions about birth trauma. Eighteen percent (n=209) of women reported their birth as traumatic. Factors associated with reporting birth as traumatic included a history of depression, raised EPDS scores (>12), induction of labour, combined ventouse/forceps birth, and postpartum haemorrhage. Of these 209 women, 134 went on to complete the City Birth Trauma Scale (Ayers et al., 2018). The average score was 3.84 and 6 of this sample (4%) reached the threshold for postpartum post-traumatic stress disorder (PTSD). KEY CONCLUSIONS: This study identified a prevalence of 18% of women experiencing birth as traumatic and the potentially important role of a current and past history of depression, postpartum haemorrhage, induction of labour and operative vaginal birth in defining a traumatic birth experience. The majority of women were resilient to birth trauma, few developed PTSD , but a larger cohort had significant functional impairment associated with sub-clinical postpartum PTSD symptoms. IMPLICATIONS FOR PRACTICE: Maternity care providers should be aware of the risk factors for traumatic birth. Introducing a trauma-informed approach amongst midwives and maternity care providers in the postnatal period may help to detect emerging or established persisting trauma-related symptoms. For women with sub-clinical postpartum PTSD symptoms a detailed enquiry may be more effective in identifying postpartum PTSD at a later postnatal stage e.g., at six weeks postpartum. Maternity services should provide ongoing supports for women who have experienced birth trauma.

Medical management of first trimester miscarriage: a quality improvement initiative.

INTRODUCTION: Medical management of first trimester pregnancy loss is a safe option that is well tolerated and affords women more autonomy in relation to their care. Recent trials provide robust evidence that mifepristone pretreatment is the optimal approach for women with missed miscarriage who desire medical management. METHODS: Following a change in medical management of first trimester miscarriage in our unit, we conducted a retrospective audit over a 3-month period of all women who had elected medical management as their primary treatment option. We compared the results with a previous audit that had been undertaken prior to the change in practice. RESULTS: The implementation of mifepristone resulted in an increased effectiveness of primary medical treatment for first trimester miscarriage from 53.8% to 85.2% (p=<0.001). DISCUSSION: The results of our study support the introduction of mifepristone into routine clinical practice for medical management of first trimester pregnancy loss across all maternity units.

Major obstetric haemorrhage: Incidence, management and quality of care in Irish maternity units.

OBJECTIVE: To assess major obstetric haemorrhage incidence, management and quality of care in Irish maternity units. DESIGN: In collaboration with Irish maternity units the National Perinatal Epidemiology Centre (Leitao et al., 2020) carried out a national clinical audit and surveillance of major obstetric haemorrhage (MOH). METHODS: MOH was defined as blood loss of at least 2500 ml, transfusion of five or more units of blood or documented treatment for coagulopathy. Co-ordinators in maternity units completed detailed case assessment forms. The denominator data obtained from the individual units was restricted to live births and stillbirths of babies weighing at least 500 g. International Classification of Diseases diagnostic codes from hospital discharge records were used to identify cases of postpartum haemorrhage (PPH) and blood transfusion. RESULTS: During the time period, 2011-2018, there was a 54 % increase in MOH, a 60 % increase in PPH and a 54 % increase in blood transfusion. For 497 reported cases of MOH in 2011-2013, the median estimated blood loss was 3000 ml (range: 600-13,000 ml) and uterine atony was the most common cause. At least one uterotonic agent was used to arrest the bleeding in 94 % of the 477 MOH cases associated with a vaginal or caesarean delivery. A blood transfusion was received in 93 % of cases. Regarding quality of care, the vast majority of reported cases were described as receiving appropriate care and were well managed. CONCLUSION: Internationally, obstetric haemorrhage and especially PPH and its increasing trend remains a major challenge for service providers and clinical staff. A standardisation of definitions of PPH/severe PPH/MOH and agreed approaches to quantitation of blood loss would be valuable developments to allow better investigation and shared learning. Reducing the burden of this morbidity through improvements in care should be a real focus of maternity services.

Early onset preeclampsia is associated with an elevated mean platelet volume (MPV) and a greater rise in MPV from time of booking compared with pregnant controls: results of the CAPE study.

OBJECTIVE: To characterise Mean platelet volume (MPV) in patients with early onset preeclampsia (EOPE) and unaffected controls from time of first antenatal visit until the postpartum. MATERIALS AND METHODS: Retrospective secondary analysis of an observational study in an Irish tertiary referral centre with 9000 deliveries annually. The MPV of 27 women with EOPE was compared to 19 unaffected controls. The inclusion criteria for the disease state was the development of EOPE defined by the National Institute for Health and Care Excellence (NICE) guideline, as new onset hypertension presenting after 20 weeks and prior to 34 weeks with significant proteinuria. Between October 2013 and July 2015 we recruited 27 women with EOPE and 19 pregnant controls. Statistical analysis was performed using paired T-test of Mann-Whitney test where appropriate and a P-value <0.05 was deemed significant. RESULTS: At time of diagnosis and late in the third trimester MPV was significantly increased to 9.0 (±0.3) fL in cases of EOPE in comparison to 8.5 (±0.6) fL in normotensive controls (P<0.05). There was no significant difference during the first trimester or postpartum when comparing the MPV in EOPE to controls. CONCLUSION: Despite an increased MPV at time of diagnosis of EOPE this study did not demonstrate a potential use for increased MPV as a first trimester screening tool.

Thrombocalc: implementation and uptake of personalized postpartum venous thromboembolism risk assessment in a high-throughput obstetric environment.

INTRODUCTION: Venous thromboembolism risk assessment (VTERA) is recommended in all pregnant and postpartum women. Our objective was to develop, pilot and implement a user-friendly electronic VTERA tool. MATERIAL AND METHODS: We developed "Thrombocalc", an electronic VTERA tool using Microsoft EXCEL™ . Thrombocalc was designed as a score-based tool to facilitate rapid assessment of all women after childbirth. Calculation of a total score estimated risk of venous thromboembolism in line with consensus guidelines. Recommendations for thromboprophylaxis were included in the VTERA output. Implementation was phased. Uptake of the VTERA tool was assessed prospectively by monitoring the proportion of women who gave birth in our institution and had a completed risk assessment. Factors affecting completion and accuracy of risk assessments were also assessed. RESULTS: Thrombocalc was used prospectively to risk-assess 8380 women between September 2014 and December 2015. Compliance with this tool increased dramatically throughout the study period; over 92% of women were risk-assessed in the last quarter of data collection. Compliance was not adversely affected if delivery took place out of working hours [adjusted odds ratio (aOR) 1.03, 95% confidence interval (CI) 0.93-1.14]. Risk assessment was less likely in the case of cesarean deliveries (aOR 0.66, 95% CI 0.60-0.73) and stillborn infants (aOR 0.48, 95% CI 0.29-0.79). Misclassification of risk factors led to approximately 207 (2.5%) inaccurate thromboprophylaxis recommendations. CONCLUSIONS: Our electronic, score-based VTERA tool provides a highly effective mechanism for rapid assessment of individual postpartum venous thromboembolism risk in a high-throughput environment.

Elevated plasma TFPI activity causes attenuated TF-dependent thrombin generation in early onset preeclampsia.

Early onset preeclampsia (EOP) is a pregnancy-specific proinflammatory disorder that is characterised by competing thrombotic and bleeding risks. It was the aim of this study to characterise thrombin generation, a major determinant of thrombotic and bleeding risk, in order to better understand the haemostatic balance in patients with EOP. Patients with EOP were recruited at the Rotunda Hospital, Dublin. Twenty-six cases of EOP were recruited over a 21-month period, out of 15,299 deliveries at the Rotunda. Blood samples were collected into sodium citrate plus corn trypsin inhibitor anticoagulated vacutainers, platelet-poor plasma was prepared, and calibrated automated thrombography was used to assess thrombin generation. Results were compared to age and sex-matched non-pregnant controls (n=13) and age- and gestation-matched pregnant controls (n=20). The rate and extent of thrombin generation triggered by low-dose tissue factor (TF) was significantly reduced in patients with EOP compared to pregnant controls, most significantly in cases of severe EOP. EOP patients displayed a trend towards an increased response to endogenous activated protein C and thrombomodulin relative to pregnant controls. Plasma tissue factor pathway inhibitor (TFPI) activity was increased in EOP patients. Inhibition of TFPI abolished the attenuation of thrombin generation stimulated by low-dose TF. In conclusion, patients with EOP are characterised by an attenuated coagulation response characterised by reduced thrombin generation stimulated by low-dose TF and elevated plasma TFPI activity. These changes in coagulation may modulate thrombotic risk and bleeding risk in patients with EOP.

The effect of maternal subclinical hypothyroidism on IQ in 7- to 8-year-old children: A case-control review.

BACKGROUND: In Ireland, pregnant women are not routinely screened for subclinical hypothyroidism (SCH). AIM: Our objective was to compare the intelligence quotient (IQ) of children whose mothers had been diagnosed with SCH prenatally with matched controls using a case-control retrospective study. MATERIALS AND METHODS: In a previous study from our group, 1000 healthy nulliparous women were screened anonymously for SCH. This was a laboratory diagnosis involving elevated TSH with normal fT4 or normal TSH with hypothyroxinaemia. We identified 23 cases who agreed to participate. These were matched with 47 controls. All children underwent neurodevelopmental assessment at age 7-8. Wechsler Intelligence Scale for Children IV assessment scores were used to compare the groups. Our main outcome measure was to identify whether there was a difference in IQ between the groups. RESULTS: From the cohort of cases, 23 mothers agreed to the assessment of their children as well as 47 controls. The children in the control group had higher mean scores than those in the case group across Verbal Comprehension Intelligence, Perceptual Reasoning Intelligence, Working Memory Intelligence, Processing Speed Intelligence and Full Scale IQ. Mann-Whitney U-test confirmed a significant difference in IQ between the cases (composite score 103.87) and the controls (composite score 109.11) with a 95% confidence interval (0.144, 10.330). CONCLUSIONS: Our results highlight significant differences in IQ of children of mothers who had unrecognised SCH during pregnancy. While our study size and design prevents us from making statements on causation, our data suggest significant potential public health implications for routine prenatal screening.

Risk factors for pregnancy-associated venous thromboembolism: a review.

AIM: To critically evaluate current understanding of risk factors for pregnancy-associated venous thromboembolism (VTE) and to describe underlying molecular mechanisms. METHODS: A literature search was undertaken using the national library of medicine PubMed database. The search terms used were "pregnancy" and "venous thromboembolism". Following exclusion of unsuitable data sources, studies were identified that described specific risk factors for pregnancy-associated VTE and suggested possible underlying molecular mechanisms. Adjusted odds ratios and incident rate ratios for these specific risk factors were identified in each study and tabulated. RESULTS: A series of mainly retrospective cohort and case control studies over the past two decades have reported specific risk factors for pregnancy-associated VTE. Recent published literature has highlighted the interaction between commonly occurring risk factors, particularly the potential for a multiplicative effect on overall VTE risk, and have led to improvements in our understanding of the molecular mechanisms underlying these risk factors. CONCLUSION: Mortality from pregnancy associated VTE continues despite prevention strategies. A detailed understanding of specific risk factors, their interactions and underlying molecular mechanisms is required to identify women at highest risk and to guide development of thromboprophylaxis strategies.

A comprehensive analysis of common genetic variation around six candidate loci for intrahepatic cholestasis of pregnancy.

OBJECTIVES: Intrahepatic cholestasis of pregnancy (ICP) has a complex etiology with a significant genetic component. Heterozygous mutations of canalicular transporters occur in a subset of ICP cases and a population susceptibility allele (p.444A) has been identified in ABCB11. We sought to expand our knowledge of the detailed genetic contribution to ICP by investigation of common variation around candidate loci with biological plausibility for a role in ICP (ABCB4, ABCB11, ABCC2, ATP8B1, NR1H4, and FGF19). METHODS: ICP patients (n=563) of white western European origin and controls (n=642) were analyzed in a case-control design. Single-nucleotide polymorphism (SNP) markers (n=83) were selected from the HapMap data set (Tagger, Haploview 4.1 (build 22)). Genotyping was performed by allelic discrimination assay on a robotic platform. Following quality control, SNP data were analyzed by Armitage's trend test. RESULTS: Cochran-Armitage trend testing identified six SNPs in ABCB11 together with six SNPs in ABCB4 that showed significant evidence of association. The minimum Bonferroni corrected P value for trend testing ABCB11 was 5.81×10(-4) (rs3815676) and for ABCB4 it was 4.6×10(-7)(rs2109505). Conditional analysis of the two clusters of association signals suggested a single signal in ABCB4 but evidence for two independent signals in ABCB11. To confirm these findings, a second study was performed in a further 227 cases, which confirmed and strengthened the original findings. CONCLUSIONS: Our analysis of a large cohort of ICP cases has identified a key role for common variation around the ABCB4 and ABCB11 loci, identified the core associations, and expanded our knowledge of ICP susceptibility.

Hepatitis C virus-associated thrombocytopenia in pregnancy: impact upon multidisciplinary care provision.

OBJECTIVE: Recent studies have implicated hepatitis C virus (HCV) in the pathogenesis of immune thrombocytopenia. In pregnancy-associated immune thrombocytopenia, multidisciplinary management is required due to a potential for bleeding complications. We performed a retrospective review of HCV-infected pregnant women and age-matched controls who were not infected with HCV. METHODS: One hundred and six women with a HCV viral load were identified from 2009 to 2011. RESULTS: Thrombocytopenia was identified in 10.3% of HCV-infected pregnant women and 1.6% of age-matched controls (P<0.001). Mean platelet count during pregnancy was 120 ± 23 × 109/L in HCV-infected women and at delivery was significantly lower in HCV-infected women than in controls (P=0.01). Despite the significant difference in platelet counts, there was no significant difference in estimated blood loss (EBL) at delivery. Regional anaesthesia was performed in 73% of thrombocytopenic HCV-infected women and no complications were recorded. There were no fetal bleeding complications. CONCLUSION: In the first study to date to investigate the impact of HCV on maternal platelet count we demonstrated a significantly higher frequency of thrombocytopenia and a significantly lower platelet count in HCV-infected pregnant women compared with controls. Interestingly, thrombocytopenia had no detectable impact on EBL at delivery.

Subclinical hypothyroidism as a risk factor for placental abruption: evidence from a low-risk primigravid population.

BACKGROUND: Subclinical thyroid hypofunction in pregnancy has been shown to have an association with neurodevelopmental delay in the offspring. It is unclear whether obstetric factors may account for this observation. AIMS: To establish the prevalence of subclinical hypothyroidism (SCH) in a low-risk primigravid population and to explore its association with obstetric sequelae. MATERIALS AND METHODS: Nine hundred and fifty-three primigravid women had thyroid hormone indices analysed in the early second trimester. Delivery and neonatal outcomes were available for 904 women who met the criteria for inclusion in the study. Women with subclinical hypothyroidism (thyroid-stimulating hormone (TSH) values at or above the 98th percentile with a normal free thyroxine (fT4)) or isolated maternal hypothyroxinaemia (fT4 level at or below the second percentile with a normal-range TSH) were compared with biochemically euthyroid controls. Chi-squared test and analysis of variance were used for statistical analysis. RESULTS: The prevalence of SCH or isolated maternal hypothyroxinaemia was 4%. Positivity for antithyroid peroxidase (TPO) or antithyroglobulin (ATG) antibodies correlated with SCH status (P = 0.02). Placental abruption was observed more commonly in the setting of either SCH or isolated maternal hypothyroxinaemia when compared with euthyroid controls (P = 0.02 and 0.04, respectively). CONCLUSIONS: Subclinical hypothyroidism and isolated maternal hypothyroxinaemia are associated with placental abruption. The observation of these effects in this healthy low-risk population lends weight to the case for antenatal screening for diminished thyroid reserve.

The correlation of ultrasonographic placental architecture with placental histology in the low-risk primigravid population.

AIM: To determine the association, if any, between placental architecture findings assessed ultrasonographically at 22 and 36 weeks and placental histology. METHODS: There was prospective recruitment of 1011 low-risk primigravids from the antenatal clinic at the Rotunda Hospital, Dublin, Ireland. Ultrasound of the placenta was performed at 22 and 36 weeks and histological assessment was made of the placenta of all participants. RESULTS: Complete data pertaining to ultrasound and placental histology was available for 810 women (80%). Placental calcification on ultrasound in the third trimester was associated with a higher incidence of placental infarction identified following placental histology (80.0% vs. 21.5%; P=0.009: r=0.115). The placental thickness on ultrasound in the second trimester was less in cases complicated by chorioamnionitis (2.62 cm vs. 3.07 cm; P=0.039: r=-0.176). Chronic villitis was associated with a statistically significant increased incidence of antenatal placental infarction identified on ultrasound in the third trimester (10.7% vs. 1.9%; P=0.020: r=0.113). Intervillous thrombi occurred more frequently in cases with reduced placental thickness on ultrasound in the second trimester (3.0 cm vs. 3.3 cm; P=0.035: r=-0.171). CONCLUSIONS: Antenatal ultrasound of the placenta may aid detection of placental disease, particularly in the identification of placental infarction.

Contaminación del aire interior y su impacto en la patología respiratoria / Indoor Air Contaminants and their Impact on Respiratory Pathologies

El ser humano pasa una parte considerable de su tiempo respirando el aire de espacios cerrados en los que, por medio de muy diversas fuentes, pueden generarse contaminantes que deterioren su calidad y constituyan un importante factor de riesgo para la salud de la población en general. En esta revisión se desarrollan los contaminantes presentes en el aire de espacios interiores, describiendo las fuentes que los generan, los mecanismos fisiopatológicos y las enfermedades que pueden producir en el aparato respiratorio(AU)

Humans spend a considerable amount of their time breathing air inside enclosed spaces in which, due to various sources, there may be contaminants that deteriorate the air quality. This is an important risk factor for the health of the general population. This review evaluates the contaminants that are present in the air of indoor air spaces, describing the sources that generate them as well as the physiopathological mechanisms and the diseases that they may cause in the respiratory system(AU)

The placenta in infants >36 weeks gestation with neonatal encephalopathy: a case control study.

OBJECTIVE: To determine placental characteristics associated with neonatal encephalopathy (NE) and correlate these with short- and long-term neurodevelopmental outcome. DESIGN: Case/control study. SETTING: Neonatal Intensive Care Unit, Rotunda Hospital, Dublin, Ireland. PATIENTS: Newborns ≥36 weeks gestation, with NE (cases). Healthy term newborns (controls). INTERVENTIONS: Placental pathology was obtained from the official placental report. Brain MRI was blindly reviewed. Children were assessed using a variety of standardised assessments. Data were analysed using multinomial logistic regression analysis. MAIN OUTCOME MEASURES: RRR for grade of encephalopathy. OR for neurodevelopmental outcome. RESULTS: Placental reports were available on 141 cases (76 grade 1; 46 grade 2; 19 grade 3) and 309 control infants. Meconium phagocytosis, haemorrhage, raised placental to birth weight ratio and/or markers of infection/inflammation were independently associated with NE and showed a synergistic effect, when combined, for short- and long-term impairments. CONCLUSIONS: Evaluation of the mechanisms leading to the placental characteristics identified may help to characterise the causal pathway of NE.

Antenatal suspicion of ischemic placental disease and coexistence of maternal and fetal placental disease: analysis of over 500 cases.

OBJECTIVE: To investigate the antenatal suspicion of placental disease and the coexistence of maternal and fetal placental ischemic disease. STUDY DESIGN: A prospective cohort study on normally formed singleton infants from 2000 to 2008 inclusive with placental ischemic disease. RESULTS: Uteroplacental ischemia or fetoplacental thrombotic vasculopathy was identified in 511 of 74,857 births (7/1000 births). Four hundred fifty-nine cases met the inclusion criteria. Maternal and fetal placental vascular disease coexisted in 9.2% (n = 42) of cases. Placental ischemic disease was suspected antenatally in 70% (324/459). Maternal placental disease occurred in 40% (184/459) and 30% (140/459) had fetal pathology. The perinatal mortality rate was 12.7/1000. Antenatal suspicion of placental disease led to increased obstetric intervention and delivery of small-for-gestational age infants. CONCLUSION: Maternal and fetoplacental vascular disease coexisted in 9.2%. Placental disease was suspected antenatally in 70% of cases and was associated with increased rates of obstetric intervention.

Laboratory assessment of iron status in pregnancy.

BACKGROUND: Efforts to improve maternal nutrition during pregnancy prompted an observational study of the occurrence of maternal iron deficiency and its laboratory diagnosis in almost 500 pregnancies. METHODS: In this longitudinal study, the biochemical and haematological iron indices of women (n=492) attending a prenatal clinic in a Dublin maternity hospital were assessed at first booking (mean 15.9 weeks), and after 24 weeks, and 36 weeks of gestation. Full blood counts were measured. Serum ferritin (SF), zinc protoporphyrin (ZPP), and transferrin receptor (sTfR) concentrations were assayed and transferrin receptor index (sTfR-Index) was calculated. The occurrence of low values and their diagnostic values were considered. RESULTS: A high occurrence iron deficiency (ID) at first booking (SF<12 µg/L) had increased over six-fold by 24 weeks, and all biochemical iron indices reflected progressive iron depletion right up to term. The WHO recommended anaemia "cut-off" (Hb<110 g/L) was insensitive to biochemical iron deficiency at booking, missing over 90% of the low SF values (SF<12 µg/L) which were mostly associated with much higher Hb levels. CONCLUSIONS: This study stresses the importance of including a biochemical index of iron status in prenatal screening and supports SF as the best indicator of biochemical ID overall. sTfR was insensitive to iron deficiency in early pregnancy, whereas the sTfR-Index, as a ratio, has the potential to distinguish between ID and physiological anaemia, and may offer stability in the assessment of iron stores from early pregnancy to full term. A policy of early screening of both Hb and SF concentrations is recommended as the minimum requirement for surveillance of maternal iron status in pregnancy.