Introduction and Background: In normal haemoglobin AA (HbAA) pregnancy, plasma volume (PV) expands and is associated with good foetomaternal outcomes. It is thought to be partly due to vasodilation in pregnancy which stimulates the renin-angiotensin-aldosterone system (RAAS). In haemoglobin SS (HbSS) pregnancy, this process fails to occur. It has been hypothesized that in HbSS pregnancy, an imbalance between the vasodilating prostacyclin and vasoconstricting thromboxane A2 (both called prostanoids) may lead to net vasoconstriction with consequent failure of PV expansion. It has also been hypothesized that a reduced glomerular filtration rate (GFR) in HbSS pregnancy could also be contributory to the poor PV expansion. This study was conducted primarily at the Lagos University Teaching Hospital (LUTH) and other government hospitals in Lagos State, Nigeria. Aim: To compare the levels of serum prostanoids and glomerular filtration rate in pregnant HbSS with pregnant HbAA patients. Methodology: This was a comparative cross-sectional study comprising four groups of normotensive, clinically stable, nulliparous Nigerian women aged between 18 – 35 years. The groups were: Pregnant HbSS (PrSS), pregnant HbAA (PrAA), non-pregnant HbSS (NPSS) and non-pregnant HbAA (NPAA). The pregnant participants were recruited between 36 - 41 weeks gestation. Stable metabolites of serum prostacyclin (6 keto-prostaglandin F1α) and thromboxane A2 (thromboxane B2) were measured by enzyme-linked immunosorbent assay and the serum creatinine was measured for the estimation of GFR with the Cockcroft-Gault formula. The haemoglobin genotype was also confirmed electrophoretically. Statistical analysis was done using the Statistical Package for the Social Sciences (SPSS) version 20. Power was 80% and α = 0.05.