The full, clinically endorsed recommendation should be obtained from Lareb [link]. 

Clinical Overview 

Nifedipine is a calcium channel blocker used in pregnancy for hypertension and as a tocolytic. It is considered a first-line option for both indications in the Netherlands. Because pregnancy-induced changes can alter drug metabolism, nifedipine has been assessed to ensure treatment remains effective and safe for both mother and foetus. 

Pharmacokinetics of nifedipine in pregnancy 

Nifedipine is mainly metabolized by the hepatic enzyme CYP3A4, whose activity increases during pregnancy. Studies show decreased nifedipine concentrations in pregnancy, particularly in the second and third trimesters. These changes may reduce effectiveness in some women. Nifedipine crosses the placenta, but information on the pharmacokinetics of nifedipine in the foetus remains limited. 

Efficacy and safety of nifedipine in pregnancy 

Clinical experience indicates that nifedipine is effective for blood pressure control and for tocolysis in pregnancy. However, there is no consensus regarding the correlation between plasma concentration and the effects of nifedipine, resulting in various values being reported as therapeutic plasma concentrations for the treatment of hypertension. For tocolysis, the therapeutic range remains unknown. Available safety data do not suggest an increased risk of congenital abnormalities. However, evidence in the first trimester is limited, and caution is advised in early pregnancy.  

Conclusion 

Pregnancy-induced changes in the pharmacokinetics of nifedipine can result in decreased exposure. Nifedipine is generally effective and safe for both hypertension treatment in pregnancy and preterm labor management.