Accuracy, User Acceptability, and Safety Evaluation for the FreeStyle Libre Flash Glucose Monitoring System When Used by Pregnant Women with Diabetes.

BACKGROUND: Accuracy of the FreeStyle Libre™ Flash Glucose Monitoring System has not been evaluated in pregnant women with diabetes. The aim of this study was to determine accuracy (compared to self-monitoring of blood glucose [SMBG]), clinical safety, and acceptability of the FreeStyle Libre System when used at home by this population. MATERIALS AND METHODS: Seventy-four participants, with type 1 (T1D, n = 24), type 2 (T2D, n = 11), or gestational (n = 39) diabetes, were enrolled across 13 sites (9 in United Kingdom, 4 in Austria). Average gestation was 26.6 ± 6.8 weeks (mean ± standard deviation), age was 30.5 ± 5.1 years, diabetes duration was 13.1 ± 7.3 years for T1D and 3.2 ± 2.5 years for T2D, and 49/74 (66.2%) used insulin to manage their diabetes. Sensors were worn for up to 14 days. Sensor glucose values (masked) were compared with capillary SMBG values (made at least 4 times/day). RESULTS: Clinical accuracy of sensor results versus SMBG results was demonstrated, with 88.1% and 99.8% of results within Zone A and Zones A and B of the Consensus Error Grid, respectively. Overall mean absolute relative difference was 11.8%. Sensor accuracy was unaffected by the type of diabetes, the stage of pregnancy, whether insulin was used, age or body mass index. User questionnaires indicated high levels of satisfaction with sensor wear, system use, and comparison to SMBG. There were no unanticipated device-related adverse events. CONCLUSIONS: Good agreement was demonstrated between the FreeStyle Libre System and SMBG. Accuracy of the system was unaffected by patient characteristics, indicating that the system is safe and accurate to use by pregnant women with diabetes.

A cost-effectiveness comparison of the NICE 2015 and WHO 2013 diagnostic criteria for women with gestational diabetes with and without risk factors.

OBJECTIVES: To compare the cost-effectiveness (CE) of the National Institute for Health and Care Excellence (NICE) 2015 and the WHO 2013 diagnostic thresholds for gestational diabetes mellitus (GDM). SETTING: The analysis was from the perspective of the National Health Service in England and Wales. PARTICIPANTS: 6221 patients from four of the Hyperglycaemia and Adverse Pregnancy Outcomes (HAPO) study centres (two UK, two Australian), 6308 patients from the Atlantic Diabetes in Pregnancy study and 12 755 patients from UK clinical practice. PRIMARY AND SECONDARY OUTCOME MEASURES PLANNED: The incremental cost per quality-adjusted life year (QALY), net monetary benefit (NMB) and the probability of being cost-effective at CE thresholds of £20 000 and £30 000 per QALY. RESULTS: In a population of pregnant women from the four HAPO study centres and using NICE-defined risk factors for GDM, diagnosing GDM using NICE 2015 criteria had an NMB of £239 902 (relative to no treatment) at a CE threshold of £30 000 per QALY compared with WHO 2013 criteria, which had an NMB of £186 675. NICE 2015 criteria had a 51.5% probability of being cost-effective compared with the WHO 2013 diagnostic criteria, which had a 27.6% probability of being cost-effective (no treatment had a 21.0% probability of being cost-effective). For women without NICE risk factors in this population, the NMBs for NICE 2015 and WHO 2013 criteria were both negative relative to no treatment and no treatment had a 78.1% probability of being cost-effective. CONCLUSION: The NICE 2015 diagnostic criteria for GDM can be considered cost-effective relative to the WHO 2013 alternative at a CE threshold of £30 000 per QALY. Universal screening for GDM was not found to be cost-effective relative to screening based on NICE risk factors.

Determining the Optimal Protocol for Measuring an Albuminuria Class Transition in Clinical Trials in Diabetic Kidney Disease.

Albuminuria class transition (normo- to micro- to macroalbuminuria) is used as an intermediate end point to assess renoprotective drug efficacy. However, definitions of such class transition vary between trials. To determine the most optimal protocol, we evaluated the approaches used in four clinical trials testing the effect of renin-angiotensin-aldosterone system intervention on albuminuria class transition in patients with diabetes: the BENEDICT, the DIRECT, the ALTITUDE, and the IRMA-2 Trial. The definition of albuminuria class transition used in each trial differed from the definitions used in the other trials by the number (one, two, or three) of consecutively collected urine samples at each study visit, the time interval between study visits, the requirement of an additional visit to confirm the class transition, and the requirement of a percentage increase in albuminuria from baseline in addition to the class transition. In Cox regression analysis, neither increasing the number of urine samples collected at a single study visit nor differences in the other variables used to define albuminuria class transition altered the average drug effect. However, the SEM of the treatment effect increased (decreased precision) with stricter end point definitions, resulting in a loss of statistical significance. In conclusion, the optimal albuminuria transition end point for use in drug intervention trials can be determined with a single urine collection for albuminuria assessment per study visit. A confirmation of the end point or a requirement of a minimal percentage change in albuminuria from baseline seems unnecessary.

Reversible weakness and encephalopathy while on long-term valproate treatment due to carnitine deficiency.

We describe a case of a 35-year-old woman who presented with bilateral leg weakness and encephalopathy while on long-term valproate therapy. She was diagnosed with valproate-induced encephalopathy due to carnitine deficiency. Clinical improvement occurred with oral carnitine supplementation. Our case report highlights the importance of considering carnitine deficiency in patients presenting with unexplained neurological signs while on long-term valproate treatment.

Diagnosis of gestational diabetes, defining the net, refining the catch.

The blood glucose diagnostic thresholds for gestational diabetes remain controversial. In the UK the National Institute for Health and Care Excellence (NICE) has published updated guidance for its diagnosis based upon a health economic analysis using local population datasets, and treatment effects estimated from published intervention trials. The resulting thresholds differ from those of the WHO, and in this issue of Diabetologia (DOI: 10.1007/s00125-015-3647-z ), Meek et al have compared the impact of the two sets of diagnostic criteria on 25,543 pregnant women cared for at their unit in Cambridge, UK. This commentary discusses their paper and its implications for pregnant women in the UK.

Risk and recurrence of serious adverse outcomes in the first and second pregnancies of women with preexisting diabetes.

OBJECTIVE: Women with preexisting (type 1 or type 2) diabetes experience an increased risk of serious adverse pregnancy outcomes. It is not known, however, how these risks change between the first and second pregnancy and whether there is an increased risk of recurrence. This study describes the absolute risks and recurrence of serious adverse pregnancy outcomes in 220 women with preexisting diabetes. RESEARCH DESIGN AND METHODS: A total of 440 pregnancies occurring in 220 women with preexisting diabetes who delivered successive singleton pregnancies in the North of England during 1996-2008 were identified from the Northern Diabetes in Pregnancy Survey (NorDIP). Predictors of serious adverse outcome were estimated by competing-risks regression. RESULTS: Sixty-seven first pregnancies (30.5%) ended in serious adverse outcome, including 14 (6.4%) with congenital anomalies and 53 (24.1%) additional fetal or infant deaths. Thirty-seven second pregnancies (16.8%) ended in serious adverse outcome--half the rate among first pregnancies (P = 0.0004)--including 21 (9.5%) with congenital anomalies and 16 (7.3%) additional fetal or infant deaths. Serious adverse outcomes in the second pregnancy occurred twice as frequently in women who experienced a previous adverse outcome than in those who did not (26.9% vs. 12.4%, P = 0.004), but previous adverse outcome was not associated with preparation for the following pregnancy. CONCLUSIONS: Serious adverse outcomes are less common in the second pregnancies of women with preexisting diabetes, although the risk is comparable in those whose first pregnancy ends in adverse outcome. Reducing the risk of recurrence may require more support in the immediate period after an adverse pregnancy outcome.

Pre-existing diabetes, maternal glycated haemoglobin, and the risks of fetal and infant death: a population-based study.

AIMS/HYPOTHESIS: Pre-existing diabetes is associated with an increased risk of stillbirth, but few studies have excluded the effect of congenital anomalies. This study used data from a long-standing population-based survey of women with pre-existing diabetes to investigate the risks of fetal and infant death and quantify the contribution of glycaemic control. METHODS: All normally formed singleton offspring of women with pre-existing diabetes (1,206 with type 1 diabetes and 342 with type 2 diabetes) in the North of England during 1996-2008 were identified from the Northern Diabetes in Pregnancy Survey. RRs of fetal death (≥20 weeks of gestation) and infant death were estimated by comparison with population data from the Northern Perinatal Morbidity and Mortality Survey. Predictors of fetal and infant death in women with pre-existing diabetes were examined by logistic regression. RESULTS: The prevalence of fetal death in women with diabetes was over four times greater than in those without (RR 4.56 [95% CI 3.42, 6.07], p < 0.0001), and for infant death it was nearly doubled (RR 1.86 [95% CI 1.00, 3.46], p = 0.046). There was no difference in the prevalence of fetal death (p = 0.51) or infant death (p = 0.70) between women with type 1 diabetes and women with type 2 diabetes. There was no evidence that the RR of fetal and infant death had changed over time (p = 0.95). Increasing periconception HbA1c concentration above 49 mmol/mol (6.6%) (adjusted odds ratio [aOR] 1.02 [95% CI 1.00, 1.04], p = 0.01), prepregnancy retinopathy (aOR 2.05 [95% CI 1.04, 4.05], p = 0.04) and lack of prepregnancy folic acid consumption (aOR 2.52 [95% CI 1.12, 5.65], p = 0.03) were all independently associated with increased odds of fetal and infant death. CONCLUSIONS/INTERPRETATION: Pre-existing diabetes is associated with a substantially increased risk of fetal and infant death in normally formed offspring, the effect of which is largely moderated by glycaemic control.

Irbesartan delays progression of nephropathy as measured by estimated glomerular filtration rate: post hoc analysis of the Irbesartan Diabetic Nephropathy Trial.

BACKGROUND: The Irbesartan Diabetic Nephropathy Trial (IDNT) demonstrated that irbesartan significantly slowed established Type 2 diabetic nephropathy progression. Estimated glomerular filtration rate (eGFR), now widely used to monitor chronic kidney disease (CKD) progression, was not previously examined in IDNT. This post hoc analysis aimed to confirm IDNT results using eGFR as principal outcome measure. METHODS: Mean change in eGFR from baseline (ΔeGFR) was analysed using linear mixed-effects models over time and analysis of covariance at end of study on an intention-to-treat basis. Potential treatment response moderators and/or mediators assessed were CKD stage, blood pressure (BP) and proteinuria. RESULTS: Irbesartan significantly slowed the rate of ΔeGFR decline from 6 to 21 months (P = 0.0048) and 24 to 48 months (P < 0.0001) versus amlodipine and placebo, despite a faster decline in the first month. The longer patients remained on irbesartan the greater the benefit (model-derived estimates for 6-21 and 24-48 month periods were -0.3354 and -0.1947 mL/min/1.73 m(2)/month, respectively). Irbesartan slowed the rate of ΔeGFR decline irrespective of baseline CKD stage, BP or proteinuria level. Irbesartan produced rapid and sustained proteinuria reductions, which only partially mediated treatment response. Irbesartan increased serum potassium, but levels stabilized from 6 to 48 months. CONCLUSIONS: In patients with established Type 2 diabetic nephropathy and CKD Stages 1-5, irbesartan safely and significantly slowed the rate of ΔeGFR decline (-2.34 mL/min/1.73 m(2)/year) compared to amlodipine (-3.76 mL/min/1.73 m(2)/year) and placebo (-3.52 mL/min/1.73 m(2)/year). This rate of decline was slower with longer duration of irbesartan treatment and only partly explained by observed reductions in BP and proteinuria.

Effect of candesartan on microalbuminuria and albumin excretion rate in diabetes: three randomized trials.

BACKGROUND: Microalbuminuria in diabetes is strongly predictive of nephropathy, end-stage renal disease, and premature cardiovascular morbidity and mortality. Effective preventive therapies are therefore a clinical priority. OBJECTIVE: To determine whether the angiotensin-receptor blocker candesartan compared with placebo affects microalbuminuria incidence or rate of change in albuminuria in type 1 and type 2 diabetes. DESIGN: 3 randomized trials of the DIRECT (Diabetic Retinopathy Candesartan Trials) Program. SETTING: 309 secondary care centers. PATIENTS: 3326 and 1905 patients with type 1 and type 2 diabetes, respectively. Most were normotensive, and all had normoalbuminuria (median urinary albumin excretion rate, 5.0 microg/min). INTERVENTION: Candesartan, 16 mg/d increasing to 32 mg/d, versus placebo. Assignment was done centrally using an interactive voice-response system. Patients, caregivers, and researchers were blinded to treatment assignment. During a median follow-up of 4.7 years, 793 patients discontinued therapy and 63 were lost to follow-up. MEASUREMENTS: Urinary albumin excretion rate, assessed annually by 2 overnight collections; if it was 20 microg/min or greater, then 2 further collections were done. The primary end point was new microalbuminuria (3 or 4 collections of urinary albumin excretion rate >or=20 microg/min). The secondary end point was rate of change in albuminuria. RESULTS: Individual and pooled results of the 3 trials showed that candesartan had little effect on risk for microalbuminuria (pooled hazard ratio, 0.95 [95% CI, 0.78 to 1.16]; P = 0.60). Pooled results showed that the annual rate of change in albuminuria was 5.53% lower (CI, 0.73% to 10.14%; P = 0.024) with candesartan than with placebo. LIMITATIONS: Investigators recruited mainly normotensive patients or patients with well-controlled hypertension who were at low overall vascular risk, which resulted in a low rate of microalbuminuria. Studies were powered for retinal and not renal end points. CONCLUSION: Candesartan, 32 mg/d, for 4.7 years did not prevent microalbuminuria in mainly normotensive patients with type 1 or type 2 diabetes.

Cigarette smoking during pregnancy is associated with alterations in maternal and fetal thyroid function.

CONTEXT: Studies in the general population have shown lower serum TSH levels in smokers as compared with nonsmokers. AIM: Our aim was to examine whether smoking is associated with changes in thyroid function of pregnant women and their fetus. SUBJECTS AND METHODS: We examined the relationship between smoking and thyroid function (serum TSH, free T4, and free T3) in two independent cohorts of pregnant women without a history of thyroid disorder or an overt biochemical thyroid dysfunction: 1) first-trimester cohort (median gestation 9 wk) (n = 1428) and 2) third-trimester cohort (gestation 28 wk) (n = 927). We also analyzed the relationship between maternal smoking and thyroid hormone levels in cord serum of 618 full-term babies born to the women in the third-trimester cohort. RESULTS: In smokers compared with nonsmokers, median serum TSH was lower (first-trimester cohort: 1.02 vs. 1.17 mIU/liter, P = 0.001; third-trimester cohort: 1.72 vs. 1.90 mIU/liter, P = 0.037), and median serum FT3 was higher (first-trimester cohort: 5.1 vs. 4.9 pmol/liter, P < 0.0001; third-trimester cohort: 4.4 vs. 4.1 pmol/liter, P < 0.0001). In both cohorts, serum FT4 in smokers and nonsmokers were similar. The prevalence of anti-thyroperoxidase antibodies was also similar in smokers and nonsmokers in both cohorts. Cord serum TSH of babies born to smokers was lower than of those born to nonsmokers (6.7 vs. 8.1 mIU/liter, P = 0.009). CONCLUSIONS: Cigarette smoking is associated with changes in maternal thyroid function throughout the pregnancy and in fetal thyroid function as measured in cord blood samples.

Effect of candesartan on prevention (DIRECT-Prevent 1) and progression (DIRECT-Protect 1) of retinopathy in type 1 diabetes: randomised, placebo-controlled trials.

BACKGROUND: Results of previous studies suggest that renin-angiotensin system blockers might reduce the burden of diabetic retinopathy. We therefore designed the DIabetic REtinopathy Candesartan Trials (DIRECT) Programme to assess whether candesartan could reduce the incidence and progression of retinopathy in type 1 diabetes. METHODS: Two randomised, double-blind, parallel-design, placebo-controlled trials were done in 309 centres worldwide. Participants with normotensive, normoalbuminuric type 1 diabetes without retinopathy were recruited to the DIRECT-Prevent 1 trial and those with existing retinopathy were recruited to DIRECT-Protect 1, and were assigned to candesartan 16 mg once a day or matching placebo. After 1 month, the dose was doubled to 32 mg. Investigators and participants were unaware of the treatment allocation status. The primary endpoints were incidence and progression of retinopathy and were defined as at least a two-step and at least a three-step increase on the Early Treatment Diabetic Retinopathy Study (ETDRS) scale, respectively. These trials are registered with ClinicalTrials.gov, numbers NCT00252733 for DIRECT-Prevent 1 and NCT00252720 for DIRECT-Protect 1. FINDINGS: 1421 participants (aged 18-50 years) were randomly assigned to candesartan (n=711) or to placebo (n=710) in DIRECT-Prevent 1, and 1905 (aged 18-55 years) to candesartan (n=951) or to placebo (n=954) in DIRECT-Protect 1. Incidence of retinopathy was seen in 178 (25%) participants in the candesartan group versus 217 (31%) in the placebo group. Progression of retinopathy occurred in 127 (13%) participants in the candesartan group versus 124 (13%) in the placebo group. Hazard ratio (HR for candesartan vs placebo) was 0.82 (95% CI 0.67-1.00, p=0.0508) for incidence of retinopathy and 1.02 (0.80-1.31, p=0.85) for progression of retinopathy. The post-hoc outcome of at least a three-step increase for incidence yielded an HR of 0.65 (0.48-0.87, p=0.0034), which was attenuated but still significant after adjustment for baseline characteristics (0.71, 0.53-0.95, p=0.046). Final ETDRS level was more likely to have improved with candesartan treatment in both DIRECT-Prevent 1 (odds 1.16, 95% CI 1.05-1.30, p=0.0048) and DIRECT-Protect 1 (1.12, 95% CI 1.01-1.25, p=0.0264). Adverse events did not differ between the treatment groups. INTERPRETATION: Although candesartan reduces the incidence of retinopathy, we did not see a beneficial effect on retinopathy progression.

Effect of candesartan on progression and regression of retinopathy in type 2 diabetes (DIRECT-Protect 2): a randomised placebo-controlled trial.

BACKGROUND: Diabetic retinopathy remains a leading cause of visual loss in people of working age. We examined whether candesartan treatment could slow the progression and, secondly, induce regression of retinopathy in people with type 2 diabetes. METHODS: We did a randomised, double-blind, parallel-group, placebo-controlled trial in 309 centres worldwide. We recruited normoalbuminuric, normotensive, or treated hypertensive people with type 2 diabetes with mild to moderately severe retinopathy and assigned them to candesartan 16 mg once a day or placebo. After a month, the dose was doubled to 32 mg once per day. Investigators and patients were unaware of the treatment allocation status. Progression of retinopathy was the primary endpoint, and regression was a secondary endpoint. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00252694. FINDINGS: 1905 participants (aged 37-75 years) were randomised to candesartan (n=951) or placebo (n=954). 161 (17%) patients in the candesartan group and 182 (19%) in the placebo group had progression of retinopathy by three steps or more on the Early Treatment Diabetic Retinopathy Study scale. The risk of progression of retinopathy was non-significantly reduced by 13% in patients on candesartan compared with those on placebo (hazard ratio [HR] 0.87, 95% CI 0.70-1.08, p=0.20). Regression on active treatment was increased by 34% (1.34, 1.08-1.68, p=0.009). HRs were not attenuated by adjustment for baseline risk factors or changes in blood pressure during the trial. An overall change towards less severe retinopathy by the end of the trial was observed in the candesartan group (odds 1.17, 95% CI 1.05-1.30, p=0.003). Adverse events did not differ between the treatment groups. INTERPRETATION: Treatment with candesartan in type 2 diabetic patients with mild to moderate retinopathy might induce improvement of retinopathy.

Inducible overexpression of sFlt-1 in podocytes ameliorates glomerulopathy in diabetic mice.

OBJECTIVE: Podocyte-specific, doxycycline (DOX)-inducible overexpression of soluble vascular endothelial growth factor (VEGF) receptor-1 (sFlt-1) in adult mice was used to investigate the role of the VEGF-A/VEGF receptor (VEGFR) system in diabetic glomerulopathy. RESEARCH DESIGN AND METHODS: We studied nondiabetic and diabetic transgenic mice and wild-type controls treated with vehicle (VEH) or DOX for 10 weeks. Glycemia was measured by a glucose-oxidase method and blood pressure by a noninvasive technique. sFlt-1, VEGF-A, VEGFR2, and nephrin protein expression in renal cortex were determined by Western immunoblotting; urine sFlt-1, urine free VEGF-A, and albuminuria by enzyme-linked immunosorbent assay; glomerular ultrastructure by electron microscopy; and VEGFR1 and VEGFR2 cellular localization with Immunogold techniques. RESULTS: Nondiabetic DOX-treated transgenic mice showed a twofold increase in cortex sFlt-1 expression and a fourfold increase in sFlt-1 urine excretion (P < 0.001). Urine free VEGF-A was decreased by 50%, and cortex VEGF-A expression was upregulated by 30% (P < 0.04). VEGFR2 expression was unchanged, whereas its activation was reduced in DOX-treated transgenic mice (P < 0.02). Albuminuria and glomerular morphology were similar among groups. DOX-treated transgenic diabetic mice showed a 60% increase in 24-h urine sFlt-1 excretion and an approximately 70% decrease in urine free VEGF-A compared with VEH-treated diabetic mice (P < 0.04) and had lower urine albumin excretion at 10 weeks than VEH-treated diabetic (d) mice: d-VEH vs. d-DOX, geometric mean (95% CI), 117.5 (69-199) vs. 43 (26.8-69) mug/24 h (P = 0.003). Diabetes-induced mesangial expansion, glomerular basement membrane thickening, podocyte foot-process fusion, and transforming growth factor-beta1 expression were ameliorated in DOX-treated diabetic animals (P < 0.05). Diabetes-induced VEGF-A and nephrin expression were not affected in DOX-treated mice. CONCLUSIONS: Podocyte-specific sFlt-1 overexpression ameliorates diabetic glomerular injury, implicating VEGF-A in the pathogenesis of this complication.

Target level for hemoglobin correction in patients with diabetes and CKD: primary results of the Anemia Correction in Diabetes (ACORD) Study.

BACKGROUND: Patients with diabetes and anemia are at high risk of cardiovascular disease. The Anemia CORrection in Diabetes (ACORD) Study aimed to investigate the effect of anemia correction on cardiac structure, function, and outcomes in patients with diabetes with anemia and early diabetic nephropathy. METHODS: One hundred seventy-two patients with type 1 or 2 diabetes mellitus, mild to moderate anemia, and stage 1 to 3 chronic kidney disease were randomly assigned to attain a target hemoglobin (Hb) level of either 13 to 15 g/dL (130 to 150 g/L; group 1) or 10.5 to 11.5 g/dL (105 to 115 g/L; group 2). The primary end point was change in left ventricular mass index (LVMI). Secondary end points included echocardiographic variables, renal function, quality of life, and safety. RESULTS: Median Hb level and LVMI were similar in groups 1 and 2 (Hb, 11.9 and 11.7 g/dL [119 and 117 g/L]; LVMI, 113.5 and 112.3 g/m(2), respectively). At study end, Hb levels were 13.5 g/dL (135 g/L) in group 1 and 12.1 g/dL (121 g/L) in group 2 (P < 0.001). No significant differences were observed in median LVMI at month 15 between study groups (group 1, 112.3 g/m(2); group 2, 116.5 g/m(2)). Multivariate analysis showed a nonsignificant decrease in LVMI (P = 0.15) in group 1 versus group 2. Anemia correction had no effect on the rate of decrease in creatinine clearance, but resulted in significantly improved quality of life in group 1 (P = 0.04). There were no clinically relevant differences in adverse events between study groups. CONCLUSION: In patients with diabetes with mild to moderate anemia and moderate left ventricular hypertrophy, correction to an Hb target level of 13 to 15 g/dL (130 to 150 g/L) does not decrease LVMI. However, normalization of Hb level prevented an additional increase in left ventricular hypertrophy, was safe, and improved quality of life.

Detection of thyroid dysfunction in early pregnancy: Universal screening or targeted high-risk case finding?

CONTEXT: Maternal subclinical hypothyroidism during pregnancy is associated with various adverse outcomes. Recent consensus guidelines do not advocate universal thyroid function screening during pregnancy but recommend testing high-risk pregnant women with a personal history of thyroid or other autoimmune disorders or with a family history of thyroid disorders. OBJECTIVE: The objective of the study was to assess efficacy of the targeted high-risk case-finding approach in identifying women with thyroid dysfunction during early pregnancy. DESIGN/SETTING: This was a single-center cohort study. PATIENTS/OUTCOME MEASURES: We prospectively analyzed TSH, free T4 and free T3 in 1560 consecutive pregnant women during their first antenatal visit (median gestation 9 wk). We tested thyroperoxidase antibodies in 1327 (85%). We classified 413 women (26.5%), who had a personal history of thyroid or other autoimmune disorders or a family history of thyroid disorders, as a high-risk group. We examined whether testing only such a high-risk group would pick up most pregnant women with thyroid dysfunction. RESULTS: Forty women (2.6%) had raised TSH (>4.2 mIU/liter). The prevalence of raised TSH was higher in the high-risk group [6.8 vs. 1% in the low-risk group, relative risk (RR) 6.5, 95% confidence interval (CI) 3.3-12.6, P < 0.0001]. Presence of personal history of thyroid disease (RR 12.2, 95% CI 6.8-22, P < 0.0001) or other autoimmune disorders (RR 4.8, 95% CI 1.3-18.2, P = 0.016), thyroperoxidase antibodies (RR 8.4, 95% CI 4.6-15.3, P < 0.0001), and family history of thyroid disorders (RR 3.4, 95% CI 1.8-6.2, P < 0.0001) increased the risk of raised TSH. However, 12 of 40 women with raised TSH (30%) were in the low-risk group. CONCLUSION: Targeted thyroid function testing of only the high-risk group would miss about one third of pregnant women with overt/subclinical hypothyroidism.