Exposures to non-therapeutic chemicals before, during and after pregnancy: data from the Swiss Teratogen Information Service (STIS).

AIMS OF THE STUDY: Limited knowledge exists regarding exposures to non-therapeutic chemicals by women planning to conceive, or during pregnancy or breastfeeding. The Swiss Teratogen Information Service (STIS) provides information to healthcare professionals about medications and other exposures during pregnancy or breastfeeding. This study aimed to describe the queries on non-therapeutic chemicals addressed to the STIS over the past two decades. METHODS: Using data from the STIS for the years 2000 to 2019, we conducted a descriptive analysis of all queries related to women's exposures to non-therapeutic chemicals during pregnancy planning, pregnancy or breastfeeding. RESULTS: Over two decades, the STIS database recorded 320 exposures to chemicals. Workplace settings accounted for over 60% of queries, followed by exposures at home (20%). In almost half (48%) of the queries, more than one chemical was mentioned, totalling 885 chemicals across these 320 queries. Commonly mentioned chemicals included isopropanol, acetone and lead. Solvents were the leading category of products (16%), followed by cleaning products (10%), paints (8%) and insecticides (5%). The follow-up data showed five diverse cases of congenital malformations, accounting for 4.0% (5 out of 125) of the sample, a figure in line with the background risk of malformations in the general population. CONCLUSIONS: This study emphasises the importance of conducting research that comprehensively captures the highly heterogeneous exposures to non-therapeutic chemicals during pregnancy and suggests that attention should be given not only to professional settings, but also to domestic contexts.

Dispensed drugs during pregnancy in outpatient care between 2015 and 2021 in Switzerland: a retrospective analysis of Swiss healthcare claims data.

AIM OF THE STUDY: We aimed to evaluate the utilisation of all prescribed drugs during pregnancy dispensed in outpatient care in Switzerland between 2015 and 2021. METHODS: We conducted a descriptive study using the Swiss Helsana claims database (2015-2021). We established a cohort of pregnancies by identifying deliveries and estimating the date of the last menstrual period. We analysed the drug burden during a 270-day pre-pregnancy period, during pregnancy (overall and by trimester), and during a 270-day postpartum period. Subsequently, we quantified 1) the median number of drug dispensations (total vs. unique drug claims); and 2) the prevalence of exposure to at least one dispensed drug and the number of dispensed drugs (0, 1, 2, 3, 4, and ≥5); and 3) the 15 most frequently dispensed drugs were identified during each period, overall and stratified by maternal age. RESULTS: Among 34,584 pregnant women (5.6% of all successful pregnancies in Switzerland), 87.5% claimed at least one drug (not including vitamins, supplements, and vaccines), and 33.3% claimed at least five drugs during pregnancy. During trimester 1 alone, 8.2% of women claimed at least five distinct drugs. The proportion of women who claimed prescribed drugs was lower pre-pregnancy (69.1%) and similar postpartum (85.6%) when compared to during pregnancy (87.5%). The most frequently claimed drugs during pregnancy were meaningfully different during pregnancy than before and after. CONCLUSIONS: This study suggests that 8 of 10 women in Switzerland are exposed to prescribed drugs during pregnancy. Most drugs dispensed during pregnancy are comparatively well investigated and are considered safe. However, the high drug burden in this vulnerable patient population underlines the importance of evidence on the benefit-risk profile of individual drugs taken during pregnancy.

Paternal Valproate Treatment and Risk of Childhood Neurodevelopmental Disorders: Precautionary Regulatory Measures Are Insufficiently Substantiated.

On January 12, 2024 the safety committee of the European Medicines Agency (EMA) recommended precautionary measures over a potential risk of neurodevelopmental disorders in children born to men treated with valproate. These new measures recommend patient supervision by a specialist in the management of epilepsy, bipolar disorder, or migraine. In the United Kingdom, the Medicines and Healthcare products Regulatory Agency (MHRA) issued a far more stringent precaution, warning against prescribing valproate to anyone under 55 years of age. We, members of the European Network of Teratology Information Services (ENTIS) and the Organization of Teratology Information Specialists (OTIS), believe that the EMA and MHRA warnings were premature. We are of the opinion that the underlying scientific data do not convincingly substantiate the inference of a paternally mediated risk from valproate to children, much less to an extent that justifies these far-reaching recommendations.

A population pharmacokinetic model for sertraline in women during the perinatal period-A contribution from the ConcePTION project.

AIMS: Sertraline is frequently prescribed for mental health conditions in both pregnant and breastfeeding women. According to the limited available data, only small amounts of sertraline are transferred into human milk, yet with a large amount of unexplained interindividual variability. This study aimed to develop a population pharmacokinetic (popPK) model to describe the pharmacokinetics of sertraline during the perinatal period and explain interindividual variability. METHODS: Pregnant women treated with sertraline were enrolled in the multicenter prospective cohort SSRI-Breast Milk study. A popPK model for sertraline maternal plasma and breast milk concentrations was developed and allowed estimating the milk-to-plasma ratio (MPR). An additional fetal compartment allowed cord blood concentrations to be described. Several covariates were tested for significance. Ultimately, model-based simulations allowed infant drug exposure through placenta and breast milk under various conditions to be predicted. RESULTS: Thirty-eight women treated with sertraline were included in the study and provided 89 maternal plasma, 29 cord blood and 107 breast milk samples. Sertraline clearance was reduced by 42% in CYP2C19 poor metabolizers compared to other phenotypes. Doubling milk fat content increased the MPR by 95%. Simulations suggested a median daily infant dosage of 6.9 µg kg-1 after a 50 mg maternal daily dose, representing 0.95% of the weight-adjusted maternal dose. Median cord blood concentrations could range from 3.29 to 33.23 ng mL-1 after maternal daily doses between 25 and 150 mg. CONCLUSIONS: Infant exposure to sertraline, influenced by CYP2C19 phenotype and breast milk fat content, remains low, providing reassurance regarding the use of sertraline during pregnancy and breastfeeding.

Social determinants of antidepressant continuation during pregnancy in the USA: findings from the ABCD cohort study.

PURPOSE: Patients and healthcare professionals overestimate the risks of using antidepressants during pregnancy. According to current literature, approximately half of people stop taking an anti-depressant medication when they become pregnant. Discontinuing antidepressants during pregnancy increases risks of postnatal relapses. Factors like socioeconomic status, education, and planned pregnancies play a role in the decision to continue antidepressant medication, which can worsen disparities in maternal and child health. Our aim was to identify the sociodemographic factors associated with antidepressant continuation after awareness of pregnancy. METHODS: We used representative data from the Adolescent Brain Cognitive Development (ABCD) study that captures maternal medication during pregnancy. We identified women who used antidepressants before awareness of their pregnancy. We calculated crude and adjusted associations between sociodemographic factors and continuation of antidepressant medication during pregnancy. Our model included age, education, ethnicity, first language, household income, living with a partner, having planned the pregnancy, pregnancy duration and smoking during pregnancy. RESULTS: In total, 199 women continued antidepressants and 100 discontinued. The logistic regressions resulted in only one significant factor: first language. Native English speakers were more likely to continue medication than other mothers (adjusted OR = 14.94, 95% CI = [2.40; 291.45], p = .015). CONCLUSIONS: Language differences were associated with continuation of antidepressants. Non-native English speakers were more likely to discontinue antidepressants, which may lead to health inequities. This finding should be taken into account to reinforce information about the limited risks of antidepressants among people with non-English speaking backgrounds in the USA.

Use of GLP1 receptor agonists in early pregnancy and reproductive safety: a multicentre, observational, prospective cohort study based on the databases of six Teratology Information Services.

OBJECTIVES: Glucagon-like peptide 1 receptor agonists (GLP1-RA) are indicated for the treatment of type 2 diabetes and more recently for weight loss. The aim of this study was to assess the risks associated with GLP1-RA exposure during early pregnancy. DESIGN: This multicentre, observational prospective cohort study compared pregnancy outcomes in women exposed to GLP1-RA in early pregnancy either for diabetes or obesity treatment with those in two reference groups: (1) women with diabetes exposed to at least one non-GLP1-RA antidiabetic drug during the first trimester and (2) a reference group of overweight/obese women without diabetes, between 2009 and 2022. SETTING: Data were collected from the databases of six Teratology Information Services. PARTICIPANTS: This study included 168 pregnancies of women exposed to GLP1-RA during the first trimester, alongside a reference group of 156 pregnancies of women with diabetes and 163 pregnancies of overweight/obese women. RESULTS: Exposure to GLP1-RA in the first trimester was not associated with a risk of major birth defects when compared with diabetes (2.6% vs 2.3%; adjusted OR, 0.98 (95% CI, 0.16 to 5.82)) or to overweight/obese (2.6% vs 3.9%; adjusted OR 0.54 (0.11 to 2.75)). For the GLP1-RA group, cumulative incidence for live births, pregnancy losses and pregnancy terminations was 59%, 23% and 18%, respectively. In the diabetes reference group, corresponding estimates were 69%, 26% and 6%, while in the overweight/obese reference group, they were 63%, 29% and 8%, respectively. Cox proportional cause-specific hazard models indicated no increased risk of pregnancy losses in the GLP1-RA versus the diabetes and the overweight/obese reference groups, in both crude and adjusted analyses. CONCLUSIONS: This study offers reassurance in cases of inadvertent exposure to GLP1-RA during the first trimester of pregnancy. Due to the limited sample size, larger studies are required to validate these findings.

Safety of Monoclonal Antibodies Inhibiting PCSK9 in Pregnancy: Disproportionality Analysis in VigiBase®.

Safety data on the use of monoclonal antibodies inhibiting proprotein convertase subtilisin/kexin type 9 in pregnancy are scarce. This study queried VigiBase®, the World Health Organization global pharmacovigilance database, to search for signals of disproportionate reporting for pregnancy outcomes with alirocumab and evolocumab. As of November 22, 2023, there were 45 safety reports of exposure to evolocumab (N = 31) and alirocumab (N = 14) in pregnancy. Most of them originated from Europe (N = 25, 55.6%) and were more frequently reported by healthcare professionals (N = 35, 77.8%). Median patient age was 37 years (25th-75th percentiles; 32-41 years). Drug exposure occurred during pregnancy in 36 (80.0%) safety reports, via paternal exposure during pregnancy in four (8.9%), during lactation in three (6.7%), and in two safety reports the time of drug exposure remained unknown. Twenty safety reports (57.8%) merely reported drug exposure, while 19 (42.2%) also reported pregnancy outcomes, however, without specific maternal toxicities or patterns of birth defects. Spontaneous abortion was reported in eight safety reports without representing a signal of disproportionate reporting compared with either the full database (reporting odds ratio, ROR, 0.06 95% confidence interval, CI 0.03-0.12) or statins (ROR 0.16, 95% CI 0.08-0.32). In conclusion, this study showed that, currently, there are no signals of increased reporting of spontaneous abortion with alirocumab and evolocumab compared with the full database and statins in VigiBase®. Notwithstanding, lack of disproportionality is not synonymous with safety and, as disproportionality analyses depend on the number of safety reports that progressively accumulate in VigiBase®, they should be repeated at regular intervals to confirm the results of the present study.

Patisiran exposure in early pregnancy: a case report.

We describe here the first case of exposure to patisiran treatment, a small interfering RNA molecule, during early pregnancy of a 36-year-old woman with symptomatic hereditary transthyretin-related amyloidosis. There were no major complications during pregnancy and delivery, except for a postpartum hemorrhage due to uterine atony. Vitamin A levels had to be closely monitored during pregnancy, and vitamin A substitution adapted accordingly. There was no sign of minor or major congenital abnormalities of the baby. One month after delivery, the patient showed slight clinical and electrophysiological signs of neuropathy progression due to patisiran treatment withdrawal. Patisiran infusions were resumed 3 months after delivery. Due to the unknown teratogenic potential of patisiran, the risk of neuropathy worsening associated with withholding treatment must of course be weighed against a potential teratogenic risk of treatment during pregnancy. Vitamin A levels need to be closely assessed, and substitution must be adapted accordingly, to avoid embryofetal adverse outcome due to vitamin A deficiency or toxicity.

Transfer of cetirizine/levocetirizine into human breast milk and estimation of drug exposure to infants through breastfeeding: A human lactation study from the ConcePTION project.

Data on drug transfer into human breast milk are sparse. This study aimed to quantify concentrations of cetirizine and levocetirizine in breast milk and to estimate drug exposure to infants. Breastfeeding women at least 8 weeks postpartum and using cetirizine or its pure (R)-enantiomer levocetirizine were eligible to participate. Breast milk samples were collected at six predefined times during a dose interval (0, 2, 4, 8, 12 and 24 h after drug intake) at steady state. Infant drug exposure was estimated by calculating the absolute infant dose (AID) and the weight-adjusted relative infant dose (RID). In total, 32 women were eligible for final inclusion, 31 women using cetirizine and one woman using levocetirizine. Means of the individual maximum and average cetirizine milk concentrations were 41.0 and 16.8 µg/L, respectively. Maximum concentrations occurred on average 2.4 h after intake, and the mean half-life in milk was 7.0 h. Estimated AID and RID for cetirizine in a day were 2.5 µg/kg and 1.9%, respectively. The corresponding values for levocetirizine were 1.1 µg/kg and 1.9%. No severe adverse events were reported. Our findings demonstrate that the transfer of cetirizine and levocetirizine into breast milk is low and compatible with breastfeeding.

Improving Data Collection in Pregnancy Safety Studies: Towards Standardisation of Data Elements in Pregnancy Reports from Public and Private Partners, A Contribution from the ConcePTION Project.

INTRODUCTION AND OBJECTIVE: The ConcePTION project aims to improve the way medication use during pregnancy is studied. This includes exploring the possibility of developing a distributed data processing and analysis infrastructure using a common data model that could form a foundational platform for future surveillance and research. A prerequisite would be that data from various data access providers (DAPs) can be harmonised according to an agreed set of standard rules concerning the structure and content of the data. To do so, a reference framework of core data elements (CDEs) recommended for primary data studies on drug safety during pregnancy was previously developed. The aim of this study was to assess the ability of several public and private DAPs using different primary data sources focusing on multiple sclerosis, as a pilot, to map their respective data variables and definitions with the CDE recommendations framework. METHODS: Four pregnancy registries (Gilenya, Novartis; Aubagio, Sanofi; the Organization of Teratology Information Specialists [OTIS]; Aubagio, Sanofi; the Dutch Pregnancy Drug Register, Lareb), two enhanced pharmacovigilance programmes (Gilenya PRIM, Novartis; MAPLE-MS, Merck Healthcare KGaA) and four Teratology Information Services (UK TIS, Jerusalem TIS, Zerifin TIS, Swiss TIS) participated in the study. The ConcePTION primary data source CDE includes 51 items covering administrative functions, the description of pregnancy, maternal medical history, maternal illnesses arising in pregnancy, delivery details, and pregnancy and infant outcomes. For each variable in the CDE, the DAPs identified whether their variables were: identical to the one mentioned in the CDE; derived; similar but with a divergent definition; or not available. RESULTS: The majority of the DAP data variables were either directly taken (85%, n = 305/357, range 73-94% between DAPs) or derived by combining different variables (12%, n = 42/357, range 0-24% between DAPs) to conform to the CDE variables and definitions. For very few of the DAP variables, alignment with the CDE items was not possible, either because of divergent definitions (1%, n = 3/357, range 0-2% between DAPs) or because the variables were not available (2%, n = 7/357, range 0-4% between DAPs). CONCLUSIONS: Data access providers participating in this study presented a very high proportion of variables matching the CDE items, indicating that alignment of definitions and harmonisation of data analysis by different stakeholders to accelerate and strengthen pregnancy pharmacovigilance safety data analyses could be feasible.

[Risk assessment of drugs during breastfeeding]. / Évaluation des risques liés aux médicaments pendant l'allaitement.

Medication intake during the postpartum period is common with discontinuation of breastfeeding sometimes unnecessarily recommended for fear of adverse effects in the breastfed infant, while exposure through human milk is generally low. The assessment of risks associated with medication intake during breastfeeding is based, among other things, on the little clinical evidence available in specialized sources of information, and on pharmacokinetic principles. A decision-making support is presented to facilitate communication with mothers, foster medication adherence and prevent unnecessary interruption of breastfeeding.

La prise de médicaments pendant la période postnatale est courante et associée à un arrêt de l'allaitement parfois recommandé à tort par crainte d'effets indésirables chez l'enfant allaité, alors que l'exposition à travers le lait maternel est généralement faible. L'évaluation des risques d'utilisation de médicaments pendant l'allaitement repose, entre autres, sur le peu de preuves cliniques disponibles, documentées dans des sources d'information spécialisées, et sur les principes pharmacocinétiques. Un algorithme d'aide à la décision est proposé pour faciliter la communication avec les mères, renforcer l'adhésion thérapeutique et éviter une interruption inutile de l'allaitement.

Evolution of National Guidelines on Medicines Used to Treat COVID-19 in Pregnancy in 2020-2022: A Scoping Review.

The lack of inclusion of pregnant women in clinical trials evaluating the effectiveness of medicines to treat COVID-19 has made it difficult to establish evidence-based treatment guidelines for pregnant women. Our aim was to provide a review of the evolution and updates of the national guidelines on medicines used in pregnant women with COVID-19 published by the obstetrician and gynecologists' societies in thirteen countries in 2020-2022. Based on the results of the RECOVERY (Randomized Evaluation of COVID-19 Therapy) trial, the national societies successively recommended against prescribing hydroxychloroquine, lopinavir-ritonavir and azithromycin. Guidelines for remdesivir differed completely between countries, from compassionate or conditional use to recommendation against. Nirmatrelvir-ritonavir was authorized in Australia and the UK only in research settings and was no longer recommended in the UK at the end of 2022. After initial reluctance to use corticosteroids, the results of the RECOVERY trial have enabled the recommendation of dexamethasone in case of severe COVID-19 since mid-2020. Some societies recommended prescribing tocilizumab to pregnant patients with hypoxia and systemic inflammation from June 2021. Anti-SARS-CoV-2 monoclonal antibodies were authorized at the end of 2021 with conditional use in some countries, and then no longer recommended in Belgium and the USA at the end of 2022. The gradual convergence of the recommendations, although delayed compared to the general population, highlights the importance of the inclusion of pregnant women in clinical trials and of international collaboration to improve the pharmacological treatment of pregnant women with COVID-19.

Infant exposure to Fluvoxamine through placenta and human milk: a case series - A contribution from the ConcePTION project.

Introduction: Fluvoxamine is widely used to treat depression during pregnancy and lactation. However, limited data are available on its transfer to the fetus or in human milk. This case series provides additional information on the infant exposure to fluvoxamine during pregnancy and lactation. Case presentation: Two women, aged 38 and 34 years, diagnosed with depression were treated with 50 mg fluvoxamine during pregnancy and lactation. At delivery a paired maternal and cord blood sample was collected for each woman. The first mother exclusively breastfed her child for 4 months and gave one foremilk and one hindmilk sample at 2 days and 4 weeks post-partum, whereas the second mother did not breastfeed. Results: The cord to plasma concentration ratios were 0.62 and 0.48, respectively. At 2 weeks post-partum, relative infant doses (RID) were 0.47 and 0.57% based on fluvoxamine concentrations in foremilk and hindmilk, respectively. At 4 weeks post-partum, the RIDs were 0.35 and 0.90%, respectively. The child from the first mother was born healthy and showed a normal development at the 6th, 18th and 36th month follow-ups. One of the twins from the second woman was hospitalized for hypoglycemia that was attributed to gestational diabetes and low birth weight. The second one was born healthy. Conclusion: These results suggest a minimal exposure to fluvoxamine during lactation which is in accordance with previously published data. Larger clinical and pharmacokinetic studies assessing the long-term safety of this drug during lactation and the variability of its exposure through breastmilk are warranted.

Risk of congenital malformation after first trimester mRNA COVID-19 vaccine exposure in pregnancy: the COVI-PREG prospective cohort.

OBJECTIVES: This study aimed to evaluate the risk of congenital malformation among pregnant women exposed to the mRNA COVID-19 vaccines during the first trimester of pregnancy, which is a developmental period where the foetus is at risk of teratogenicity. METHODS: Pregnant women were prospectively enrolled from March 2021 to March 2022, at the time of COVID-19 vaccination. Pregnant women exposed to at least one dose of mRNA COVID-19 vaccine from conception to 11 weeks of gestations and 6 days were compared with pregnant women exposed to the vaccine from 12 weeks to the end of pregnancy. The primary outcome was a confirmed congenital malformation at birth. RESULTS: A total of 1450 pregnant women were enrolled including 124 in the first trimester and 1326 in the second and third trimester. The overall proportion of congenital malformation was 0.81% (n = 1/124; 95% CI: 0.02-4.41) and 0.83% (n = 11/1326; 95% CI: 0.41-1.48) among pregnant exposed to the COVID-19 vaccine during the first and second/third trimester, respectively. First trimester exposure was not associated with a higher risk of congenital malformation with a relative risk of 0.89 (95% CI: 0.12-6.80) with no significant changes after adjustment through exploratory analysis. CONCLUSIONS: Pregnant women exposed to mRNA COVID-19 vaccine before 12 weeks of gestation did not have an increased risk of congenital malformation compared with women exposed outside the teratogenic window. Because vaccination is safe and effective, emphasis must be placed on promoting vaccination during pregnancy.

Safety of medicines during breastfeeding - from case report to modeling: a contribution from the ConcePTION project.

INTRODUCTION: Despite many research efforts, current data on the safety of medicines during breastfeeding are either fragmented or lacking, resulting in restrictive labeling of most medicines. In the absence of pharmacoepidemiologic safety studies, risk estimation for breastfed infants is mainly derived from pharmacokinetic (PK) information on medicine. This manuscript provides a description and a comparison of the different methodological approaches that can yield reliable information on medicine transfer into human milk and the resulting infant exposure. AREA COVERED: Currently, most information on medicine transfer in human milk relies on case reports or traditional PK studies, which generate data that can hardly be generalized to the population. Some methodological approaches, such as population PK (popPK) and physiologically based PK (PBPK) modeling, can be used to provide a more complete characterization of infant medicine exposure through human milk and simulate the most extreme situations while decreasing the burden of sampling in breastfeeding women. EXPERT OPINION: PBPK and popPK modeling are promising approaches to fill the gap in knowledge of medicine safety in breastfeeding, as illustrated with our escitalopram example.

Determinants of Vaccination and Willingness to Vaccinate against COVID-19 among Pregnant and Postpartum Women during the Third Wave of the Pandemic: A European Multinational Cross-Sectional Survey.

With COVID-19 vaccination hesitancy at around 50% in the obstetric population, it is critical to identify which women should be addressed and how. Our study aimed to assess COVID-19 vaccination willingness among pregnant and postpartum women in Europe and to investigate associated determinants. This study was a cross-sectional, web-based survey conducted in Belgium, Norway, Switzerland, The Netherlands, and United Kingdom (UK) in June-August 2021. Among 3194 pregnant women, the proportions of women vaccinated or willing to be vaccinated ranged from 80.5% in Belgium to 21.5% in Norway. The associated characteristics were country of residence, chronic illness, history of flu vaccine, trimester of pregnancy, belief that COVID-19 is more severe during pregnancy, and belief that the COVID-19 vaccine is effective and safe during pregnancy. Among 1659 postpartum women, the proportions of women vaccinated or willing to be vaccinated ranged from 86.0% in the UK to 58.6% in Switzerland. The associated determinants were country of residence, chronic illness, history of flu vaccine, breastfeeding, and belief that the COVID-19 vaccine is safe during breastfeeding. Vaccine hesitancy in the obstetric population depends on medical history and especially on the opinion that the vaccine is safe and on the country of residence.

Antidiabetic Medication Utilisation before and during Pregnancy in Switzerland between 2012 and 2019: An Administrative Claim Database from the MAMA Cohort.

Background: The incidence of diabetes mellitus (both pregestational and gestational) is increasing worldwide, and hyperglycemia during pregnancy is associated with adverse pregnancy outcomes. Evidence on the safety and efficacy of metformin during pregnancy has accumulated resulting in an increase in its prescription in many reports. Aims: We aimed to determine the prevalence of antidiabetic drug use (insulins and blood glucose-lowering drugs) before and during pregnancy in Switzerland and the changes therein during pregnancy and over time. Methods: We conducted a descriptive study using Swiss health insurance claims (2012-2019). We established the MAMA cohort by identifying deliveries and estimating the last menstrual period. We identified claims for any antidiabetic medication (ADM), insulins, blood glucose-lowering drugs, and individual substances within each class. We defined three groups of pattern use based on timing of dispensation: (1) dispensation of at least one ADM in the prepregnancy period and in or after trimester 2 (T2) (pregestational diabetes); (2) dispensation for the first time in or after T2 (GDM); and (3) dispensation in the prepregnancy period and no dispensation in or after T2 (discontinuers). Within the pregestational diabetes group, we further defined continuers (dispensation for the same group of ADM) and switchers (different ADM group dispensed in the prepregnancy period and in or after T2). Results: MAMA included 104,098 deliveries with a mean maternal age at delivery of 31.7. Antidiabetic dispensations among pregnancies with pregestational and gestational diabetes increased over time. Insulin was the most dispensed medication for both diseases. Between 2017 and 2019, less than 10% of pregnancies treated for pregestational diabetes continued metformin rather than switching to insulin. Metformin was offered to less than 2% of pregnancies to treat gestational diabetes (2017-2019). Conclusion: Despite its position in the guidelines and the attractive alternative that metformin represents to patients who may encounter barriers with insulin therapy, there was reluctance to prescribe it.