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Date of issue: March 2017, Version: 2

Statins (atorvastatin, fluvastatin, pravastatin, rosuvastatin and simvastatin) are a class of HMG-CoA reductase inhibitors used to lower cholesterol. They act by inhibiting the conversion of HMG-CoA to mevalonate which is a rate-limiting step in the production of cholesterol in the liver. Statins may be indicated, as an adjunct to diet, for the treatment of primary hypercholesterolaemia or mixed dyslipidaemia when non-pharmacological treatments (e.g. diet, exercise, weight reduction) are inadequate, or for reduction of cardiovascular morbidity and mortality in manifest atherosclerotic cardiovascular disease or diabetes mellitus.

Cholesterol is required for normal development of the placenta and fetus, therefore theoretical concerns of teratogenic effects exist for any drug that inhibits endogenous cholesterol production. Retrospectively collected data from post-marketing surveillance and case reports have described malformations following statin use, however a meta-analysis and prospective cohort studies have not shown any increase in overall congenital malformation rates following first trimester exposure. Data on risk of specific malformations are, however, very limited, and as the physical features associated with inherited defects in cholesterol synthesis may be subtle, it is not possible to exclude adverse effects of statins on fetal development. Cholesterol synthesis disorders of genetic origin are also often associated with developmental, behavioural and cognitive impairment; neurodevelopmental outcomes in statin-exposed cohorts remain uninvestigated.

As yet there is no conclusive evidence of an increased risk of congenital malformation or low birth weight following statin exposure, however the available data are limited and confounded, and not all outcomes have been systematically studied. Higher rates of preterm delivery have been demonstrated in women being treated with statins but no causal association has been established. Data relating to risk of spontaneous abortion are conflicting. Current guidelines on diseases for which statins are frequently prescribed recommend that women wishing to become pregnant stop use of statins three months prior to attempting to conceive, or as soon as pregnancy is confirmed, due to the theoretical risk of fetal abnormality. Where statins are prescribed for conditions associated with high cholesterol, temporary suspension of therapy for the duration of pregnancy is not thought to compromise maternal health. Early research into the use of statins after the first trimester in the prevention of pre-eclampsia is, however, ongoing, with pilot data suggesting benefit with treatment.

Exposure to statins at any stage of pregnancy would not usually be regarded as medical grounds for termination of pregnancy. However, women exposed to statins are more likely to have other risk factors such as obesity and pre-pregnancy diabetes which confer additional independent risks to the fetus and pregnancy. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.

This is a summary of the full UKTIS monograph for health care professionals and should not be used in isolation. The full UKTIS monograph and access to any hyperlinked related documents is available to NHS health care professionals who are logged in.

If you have a patient with exposure to a drug or chemical and require assistance in making a patient-specific risk assessment, please telephone UKTIS on 0344 892 0909 to discuss the case with a teratology specialist.

If you would like to report a pregnancy to UKTIS please click here to download our pregnancy reporting form. Please encourage all women to complete an online reporting form.

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