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

Clinical Overview  

Cefazolin is the preferred antibiotic prophylaxis for surgeries during pregnancy in the Netherlands. For caesarean sections, a dose recommendation is reported, but for other surgeries no pregnancy-specific dosing guidelines exist. Due to pregnancy-induced changes in the pharmacokinetics of certain drugs, dose adjustments may be necessary to maintain effective antibiotic concentrations during pregnancy.  

Pharmacokinetics of cefazolin in pregnancy 

Pregnancy increases renal clearance, lowering plasma concentrations of cefazolin more rapidly than in non-pregnant adults. Tissue penetration into adipose is crucial for its prophylactic efficacy. The placental transfer of cefazolin appears to range between 18-45%.  

Efficacy and safety of cefazolin in pregnancy 

Clinical studies and pharmacokinetic models indicate that a 1-g dose is usually sufficient in women under 80 kg, though repeat dosing may be required after 1.5 hours. For women over 80 kg, a 2-g dose achieves adequate tissue concentrations, and higher doses offer no clear benefit. Evidence on the dose-related efficacy of cefazolin in pregnancy shows no consistent benefit of doses above 2 g. Safety evidence for cephalosporins is extensive and generally reassuring, with no overall increase in congenital malformations. A possible effect on neonatal gut microbiota has been observed, but differences resolve by early childhood.  

Conclusion  

Pregnancy enhances renal clearance of cefazolin, reducing plasma concentrations. Despite, there is no proven advantage of giving higher doses during pregnancy than the current guideline for non-pregnant women.