Background: The amniotic fluid index (AFI) is one of the parameters used to assess fetal well-being and predict perinatal outcomes. There is, however, a dearth of studies on the pregnancy outcomes of women with borderline AFI in Nigerian and African women. Aim: To compare the pregnancy outcomes of Nigerian women with borderline and normal amniotic fluid index. Subjects and Methods: This was a prospective cohort study conducted at two health facilities in Delta State, Southern Nigeria. A total of 114 pregnant women attending the antenatal clinics with singleton pregnancies at gestational age 37 to 41 + 6 weeks were recruited over a 5-month period. Fifty-seven subjects with borderline amniotic fluid index were matched with an equal number of subjects with the normal amniotic fluid index for gestational age, age of the parturient, and parity. These women were followed up till delivery, and pregnancy outcomes were determined. The data were analyzed using the Statistical Package for the Social Sciences (SPSS) version 22 software. Results: The results showed that borderline amniotic fluid index was associated with increased risk of adverse pregnancy outcomes including intrapartum fetal distress, Appearance, Pulse, Grimace, Activity, and Respiration (Apgar) score <7 in 5 min, and birthweight <2.5 kg, and these were statistically significant (P = 0.04, 0.01, and 0.04, respectively). Conclusions: Borderline AFI is associated with an increased risk of adverse pregnancy outcomes in low-risk Nigerian women.