Background: Pregnant women in malaria-endemic areas are at high risk of Plasmodium falciparum infection and its complications. This study investigated the impact of asymptomatic P. falciparum on haematological parameters of pregnant women at first antenatal visit in south-western Nigeria.

Methods: Hospital-based cross-sectional evaluation of 130 asymptomatic pregnant women was conducted. Plasmodium infection was diagnosed using Giemsa-stained blood smear microscopy and rapid diagnostic test, while haemoglobin levels (Hb), Packed Cell Volume (PCV), white blood cells (WBC) count, red blood cell (RBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC) were determined using semi-automated haematology analyser.

Results: Multigravid pregnant women presented more during their second trimester. Overall malaria prevalence in the sampled population was 14.6%. Prevalence of malaria parasitaemia was highest (68.4%) in the second trimester. P. falciparum infected pregnant women had significantly lower mean values of packed cell volume (PCV), haematocrit (Hb), and total white blood cell (WBC) compared to non-infected individuals (t = -4.07, p= 0.001; t = 3.30, p = <0.001; t = -2.77, p <0.001).

Conclusion: There is asymptomatic P. falciparum infection in the study area and this may form a reservoir for transmission . Pregnant women infected with malaria parasites exhibited important changes in haematocrit level, haemoglobin concentration, and total white blood cells. Use of anti-malaria therapy and insecticide-treated bed net would result in greater haematological benefits.