Introduction: Malaria remains a serious global health problem. Despite implementation of intermittent preventive treatment in pregnancy with sulfadoxine–pyrimethamine (IPTp‑SP), pregnant women in endemic areas remain highly susceptible to Plasmodium falciparum.

This study aims to evaluate the effect of IPTp‑SP on plasma electrolyte concentrations (Na+, K+, Cl– ) in pregnant women from Libreville using plasma samples from infected pregnant women (IPW) and non‑infected pregnant women (NIPW).

Method: A retrospective cross-sectional survey was conducted between March and September 2011 at ANC and delivery units of Libreville. All IPTp-SP users have received at most 2 doses of IPTp-SP and electrolytes levels were performed during the second and third trimesters of gestation.

Results: Among 313 pregnant women studied (88.5% NIPW, 11.5% IPW; 66.4% primigravidae; 52.7% IPTp‑SP users), the NIPW control group exhibited predominantly hypernatremia (148.8[145-152] mmol/L), normokalemia (3.9[3.69-4.66] mmol/L), and normochloremia (106[103-109] mmol/L). Malaria infection was significantly associated with hyponatremia (IPW, 132.7[128137] mmol/L). Submicroscopic infections were associated with hyponatremia and hypokalaemia. Among IPTp‑SP users, the malaria‑associated decline in natremia (IPW 143.7[132-154] mmol/L) was less pronounced than in infected women who did not receive IPTp‑SP (IPW 134[129-138] mmol/L).

Conclusion: Plasmodial infection was associated with reductions in both Na+ and K+ levels, placing pregnancy at increased risk of hyponatremia and hypokalemia, particularly in submicroscopic infections. IPTp‑SP use attenuated malaria‑related plasma electrolyte disturbances in both infected and non‑infected pregnant women, suggesting a protective effect of IPTp‑SP against hyponatremia and hypokalaemia in pregnant women in endemic settings.