Metformin in women with type 2 diabetes in pregnancy (MiTy): a multicentre, international, randomised, placebo-controlled trial.

BACKGROUND: Although metformin is increasingly being used in women with type 2 diabetes during pregnancy, little data exist on the benefits and harms of metformin use on pregnancy outcomes in these women. We aimed to investigate the effects of the addition of metformin to a standard regimen of insulin on neonatal morbidity and mortality in pregnant women with type 2 diabetes. METHODS: In this prospective, multicentre, international, randomised, parallel, double-masked, placebo-controlled trial, women with type 2 diabetes during pregnancy were randomly assigned from 25 centres in Canada and four in Australia to receive either metformin 1000 mg twice daily or placebo, added to insulin. Randomisation was done via a web-based computerised randomisation service and stratified by centre and pre-pregnancy BMI (<30 kg/m2 or ≥30 kg/m2) in a ratio of 1:1 using random block sizes of 4 and 6. Women were eligible if they had type 2 diabetes, were on insulin, had a singleton viable pregnancy, and were between 6 and 22 weeks plus 6 days' gestation. Participants were asked to check their fasting blood glucose level before the first meal of the day, before the last meal of the day, and 2 h after each meal. Insulin doses were adjusted aiming for identical glucose targets (fasting glucose <5·3 mmol/L [95 mg/dL], 2-h postprandial glucose <6·7 mmol/L [120 mg/dL]). Study visits were done monthly and patients were seen every 1-4 weeks as was needed for standard clinical care. At study visits blood pressure and bodyweight were measured; patients were asked about tolerance to their pills, any hospitalisations, insulin doses, and severe hypoglycaemia events; and glucometer readings were downloaded to the central coordinating centre. Participants, caregivers, and outcome assessors were masked to the intervention. The primary outcome was a composite of fetal and neonatal outcomes, for which we calculated the relative risk and 95% CI between groups, stratifying by site and BMI using a log-binomial regression model with an intention-to-treat analysis. Secondary outcomes included several relevant maternal and neonatal outcomes. The trial was registered with ClinicalTrials.gov, NCT01353391. FINDINGS: Between May 25, 2011, and Oct 11, 2018, we randomly assigned 502 women, 253 (50%) to metformin and 249 (50%) to placebo. Complete data were available for 233 (92%) participants in the metformin group and 240 (96%) in the placebo group for the primary outcome. We found no significant difference in the primary composite neonatal outcome between the two groups (40% vs 40%; p=0·86; relative risk [RR] 1·02 [0·83 to 1·26]). Compared with women in the placebo group, metformin-treated women achieved better glycaemic control (HbA1c at 34 weeks' gestation 41·0 mmol/mol [SD 8·5] vs 43·2 mmol/mol [-10]; 5·90% vs 6·10%; p=0·015; mean glucose 6·05 [0·93] vs 6·27 [0·90]; difference -0·2 [-0·4 to 0·0]), required less insulin (1·1 units per kg per day vs 1·5 units per kg per day; difference -0·4 [95% CI -0·5 to -0·2]; p<0·0001), gained less weight (7·2 kg vs 9·0 kg; difference -1·8 [-2·7 to -0·9]; p<0·0001) and had fewer caesarean births (125 [53%] of 234 in the metformin group vs 148 [63%] of 236 in the placebo group; relative risk [RR] 0·85 [95% CI 0·73 to 0·99]; p=0·031). We found no significant difference between the groups in hypertensive disorders (55 [23%] in the metformin group vs 56 [23%] in the placebo group; p=0·93; RR 0·99 [0·72 to 1·35]). Compared with those in the placebo group, metformin-exposed infants weighed less (mean birthweight 3156 g [SD 742] vs 3375 g [742]; difference -218 [-353 to -82]; p=0·002), fewer were above the 97th centile for birthweight (20 [9%] in the metformin group vs 34 [15%] in the placebo group; RR 0·58 [0·34 to 0·97]; p=0·041), fewer weighed 4000 g or more at birth (28 [12%] in the metformin group vs 44 [19%] in the placebo group; RR 0·65 [0·43 to 0·99]; p=0·046), and metformin-exposed infants had reduced adiposity measures (mean sum of skinfolds 16·0 mm [SD 5·0] vs 17·4 [6·2] mm; difference -1·41 [-2·6 to -0·2]; p=0·024; mean neonatal fat mass 13·2 [SD 6·2] vs 14·6 [5·0]; p=0·017). 30 (13%) infants in the metformin group and 15 (7%) in the placebo group were small for gestational age (RR 1·96 [1·10 to 3·64]; p=0·026). We found no significant difference in the cord c-peptide between groups (673 pmol/L [435] in the metformin group vs 758 pmol/L [595] in the placebo group; p=0·10; ratio of means 0·88 [0·72 to 1·02]). The most common adverse event reported was gastrointestinal (38 events in the metformin group and 38 events in the placebo group). INTERPRETATION: We found several maternal glycaemic and neonatal adiposity benefits in the metformin group. Along with reduced maternal weight gain and insulin dosage and improved glycaemic control, the lower adiposity and infant size measurements resulted in fewer large infants but a higher proportion of small-for-gestational-age infants. Understanding the implications of these effects on infants will be important to properly advise patients who are contemplating the use of metformin during pregnancy. FUNDING: Canadian Institutes of Health Research, Lunenfeld-Tanenbaum Research Institute, University of Toronto.

Research prioritization of interventions for the primary prevention of preterm birth: An international survey.

OBJECTIVE: To identify research priorities of interventions for the primary prevention of preterm birth (PTB), by conducting an international stakeholder survey. STUDY DESIGN: A prospective cross-sectional online survey was conducted in November 2016. Fifteen interventions to prevent spontaneous PTB were identified and ranked by stakeholders (n = 159) in the field of maternal and perinatal health research, using nine equally weighted criteria. Medians and interquartile ranges (IQRs) were calculated and the interventions ranked accordingly. RESULTS: Respondents to the survey were from 46 different countries, mostly from low and middle-income countries (62%, 99/159) and were mainly clinicians (80%, 127/159). Of the fifteen interventions ranked, the following five were identified as research priorities in the primary prevention of PTB: dietary counselling and nutritional education, risk scoring, vitamin D supplementation, exercise and antioxidant supplementation. CONCLUSION: We have identified research priorities of interventions to prevent spontaneous PTB through a global stakeholder survey. The interventions prioritized in this exercise can be used by researchers, grant funding bodies and research-policy decision makers to inform calls on future clinical trials or individual patient data meta-analyses on the primary prevention of PTB.

Primary and secondary prevention of preterm birth: a review of systematic reviews and ongoing randomized controlled trials.

BACKGROUND: Preterm birth (PTB) is a leading cause of perinatal morbidity and mortality. Interventions aimed at preventing PTB can be classified as primary, secondary, or tertiary prevention. OBJECTIVE: To conduct a review of systematic reviews on the effectiveness and safety of primary and secondary preterm birth prevention interventions. SEARCH STRATEGY: A systematic literature search of the Cochrane, PubMed/Medline, EMBASE and CINAHL databases was conducted on 2 September 2015, and updated on 21 November 2016. SELECTION CRITERIA: We included any published systematic review of randomized controlled trials (RCTs) or individual patient data (IPD) of RCTs related to primary or secondary prevention of PTB, published between 2005-2016 where gestational age at birth (of any interval) was a pre-specified outcome. Individual trials and non-systematic reviews were not eligible. DATA COLLECTION AND ANALYSIS: The population of interest was all pregnant women, regardless of PTB risk. The primary outcome was PTB < 37 weeks. MAIN RESULTS: In total, 112 reviews were included in this study. Overall there were 49 Cochrane and 63 non-Cochrane reviews. Eight were individual participant data (IPD) reviews. Sixty reviews assessed the effect of primary prevention interventions on risk of PTB. Positive effects were reported for lifestyle and behavioural changes (including diet and exercise); nutritional supplements (including calcium and zinc supplementation); nutritional education; screening for lower genital tract infections. Eighty-three systematic reviews were identified relating to secondary PTB prevention interventions. Positive effects were found for low dose aspirin among women at risk of preeclampsia; clindamycin for treatment of bacterial vaginosis; treatment of vaginal candidiasis; progesterone in women with prior spontaneous PTB and in those with short midtrimester cervical length; L-arginine in women at risk for preeclampsia; levothyroxine among women with tyroid disease; calcium supplementation in women at risk of hypertensive disorders; smoking cessation; cervical length screening in women with history of PTB with placement of cerclage in those with short cervix; cervical pessary in singleton gestations with short cervix; and treatment of periodontal disease. CONCLUSION: The overview serves as a guide to current evidence relevant to PTB prevention. Only a few interventions have been demononstrated to be effective, including cerclage, progesterone, low dose aspirin, and lifestyle and behavioural changes. For several of the interventions evaluated, there was insufficient evidence to assess whether they were effective or not.

Metformin in women with type 2 diabetes in pregnancy (MiTy): a multi-center randomized controlled trial.

BACKGROUND: The incidence of type 2 diabetes in pregnancy is rising and rates of serious adverse maternal and fetal outcomes remain high. Metformin is a biguanide that is used as first-line treatment for non-pregnant patients with type 2 diabetes. We hypothesize that metformin use in pregnancy, as an adjunct to insulin, will decrease adverse outcomes by reducing maternal hyperglycemia, maternal insulin doses, maternal weight gain and gestational hypertension/pre-eclampsia. In addition, since metformin crosses the placenta, metformin treatment of the fetus may have a direct beneficial effect on neonatal outcomes. Our aim is to compare the effectiveness of the addition of metformin to insulin, to standard care (insulin plus placebo) in women with type 2 diabetes in pregnancy. METHODS: The MiTy trial is a multi-centre randomized trial currently enrolling pregnant women with type 2 diabetes, who are on insulin, between the ages of 18-45, with a gestational age of 6 weeks 0 days to 22 weeks 6 days. In this randomized, double-masked, parallel placebo-controlled trial, after giving informed consent, women are randomized to receive either metformin 1,000 mg twice daily or placebo twice daily. A web-based block randomization system is used to assign women to metformin or placebo in a 1:1 ratio, stratified for site and body mass index. The primary outcome is a composite neonatal outcome of pregnancy loss, preterm birth, birth injury, moderate/severe respiratory distress, neonatal hypoglycemia, or neonatal intensive care unit admission longer than 24 h. Secondary outcomes are large for gestational age, cord blood gas pH < 7.0, congenital anomalies, hyperbilirubinemia, sepsis, hyperinsulinemia, shoulder dystocia, fetal fat mass, as well as maternal outcomes: maternal weight gain, maternal insulin doses, maternal glycemic control, maternal hypoglycemia, gestational hypertension, preeclampsia, cesarean section, number of hospitalizations during pregnancy, and duration of hospital stays. The trial aims to enroll 500 participants. DISCUSSION: The results of this trial will inform endocrinologists, obstetricians, family doctors, and other healthcare professionals caring for women with type 2 diabetes in pregnancy, as to the benefits of adding metformin to insulin in this high risk population. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: no. NCT01353391 . Registered February 6, 2009.