Background:Short inter-pregnancy interval (IPI) could have an adverse influence on pregnancy outcome especially in low-income countries. Previous researchers from sub-Saharan Africa have documented an alarming trend of short IPI but evidence is lacking on its impact on pregnancy outcome.

Objectives: To determine the impact of short IPI on pregnancy outcome in Nigeria.

Methods:This was a longitudinal study of 271 eligible, pregnant women receiving antenatal care in a tertiary hospital in Nigeria. For every consecutive pregnant woman with short IPI (< 18 months) recruited into the study; a suitable control (matched for age, parity and social class) with IPI ≥ 18 months was recruited. Data collected included socio-demographic data, IPI, current pregnancy history, gestational age, and any adverse pregnancy or perinatal outcomes. Hypotheses were tested using logistic-regression analysis where applicable. All tests were two sided, and statistical significance was considered to be at probability value of < 0.05.

Results:The mean age of the participants was 31.6 ± 4.2 years, and the mean neonatal birth weight was 3.3 ± 0.6kg. The prevalence of maternal anaemia was significantly higher in women with short IPI than in the control group (OR: 3.0; 95% CI: 1.76 – 5.09; P < 0.001). Other maternal and perinatal outcome measures including poor maternal weight gain, premature rupture of membranes, preterm labour, pregnancy-induced hypertension, third-trimester bleeding, primary postpartum haemorrhage, preterm birth, stillbirth, birth asphyxia, and low birth weight had no significant association with short IPI (P > 0.05).

Conclusions:Short IPI is associated with anaemia in pregnancy in Nigeria. However, further research with larger sample sizes and preferably randomised-controlled trials are needed to provide sound evidence on the impact of short IPI on maternal outcome in low-income countries.