Effects of aspirin and acetaminophen in pregnancy and in the newborn

Area of Science:

• Perinatal medicine
• Pharmacology
• Neonatal physiology

Background:

• Prostaglandin synthesis inhibitors are used to delay premature delivery.
• Concerns exist regarding their effects on uterine contractility, platelet function, fetal circulation, and neonatal adaptation.
• Specific risks associated with aspirin, indomethacin, and naproxen include interference with fetal circulatory pathways.

Purpose of the Study:

• To investigate the impact of aspirin on fetal lambs, specifically its effects on pulmonary arterial pressure and the ductus arteriosus.
• To evaluate the potential long-term consequences of aspirin-induced circulatory changes on neonatal pulmonary vascular resistance.
• To assess the safety profile of acetaminophen during pregnancy and in newborns.

Main Methods:

• Administration of aspirin (50-90 mg/kg fetal body weight) into the rumina of fetal lambs.
• Monitoring of pulmonary arterial pressure and assessment of ductus arteriosus constriction.
• Review of available data on acetaminophen use in pregnancy and its effects on newborns.

Main Results:

• Aspirin instillation led to a significant increase in pulmonary arterial pressure in fetal lambs.
• This pressure increase was directly correlated with constriction of the ductus arteriosus.
• Elevated pulmonary arterial pressure may stimulate muscular development in lung vasculature, potentially hindering postnatal adaptation.
• Limited data suggests acetaminophen, at therapeutic doses, has no adverse effects in pregnancy or newborns.

Conclusions:

• Inhibitors of prostaglandin synthesis, such as aspirin, pose risks to fetal circulation and postnatal adaptation.
• Aspirin's effect on the ductus arteriosus and pulmonary vasculature requires careful consideration during pregnancy.
• Acetaminophen appears to be a safer alternative, though more extensive research is needed.