Prevalence and associated factors of oligohydramnios in pregnancies beyond 36 weeks of gestation at a tertiary hospital in southwestern Uganda

Background Oligohydramnios is associated with poor maternal and perinatal outcomes. In low-resource countries, including Uganda, oligohydramnios is under-detected due to the scarcity of ultrasonographic services. We determined the prevalence and associated factors of oligohydramnios among women with pregnancies beyond 36 weeks of gestation at Mbarara Regional Referral Hospital (MRRH) in Southwestern Uganda. Methods We conducted a hospital-based cross-sectional study from November 2019 to March 2020. Included were women at gestational age > 36 weeks. Excluded were women with ruptured membranes, those in active labour, and those with multiple pregnancies. An interviewer-administered structured questionnaire was used to capture demographic, obstetric, and clinical characteristics of the study participants. We determined oligohydramnios using an amniotic fluid index (AFI) obtained using an ultrasound scan. Oligohydramnios was diagnosed in participants with AFI ≤ 5 cm. We performed multivariable logistic regression to determine factors associated with oligohydramnios. Results We enrolled 426 women with a mean age of 27 (SD ± 5.3) years. Of the 426 participants, 40 had oligohydramnios, for a prevalence of 9.4% (95%CI: 6.8–12.6%). Factors found to be significantly associated with oligohydramnios were history of malaria in pregnancy (aOR = 4.6; 95%CI: 1.5–14, P = 0.008), primegravidity (aOR = 3.7; 95%CI: 1.6–6.7, P = 0.002) and increasing gestational age; compared to women at 37–39 weeks, those at 40–41 weeks (aOR = 2.5; 95%CI: 1.1–5.6, P = 0.022), and those at > 41 weeks (aOR = 6.0; 95%CI: 2.3–16, P = 0.001) were more likely to have oligohydramnios. Conclusion Oligohydramnios was detected in approximately one out of every ten women seeking care at MRRH, and it was more common among primigravidae, those with a history of malaria in pregnancy, and those with post-term pregnancies. We recommend increased surveillance for oligohydramnios in the third trimester, especially among prime gravidas, those with history of malaria in pregnancy, and those with post-term pregnancies, in order to enable prompt detection of this complication and plan timely interventions. Future longitudinal studies are needed to assess clinical outcomes in women with oligohydramnios in our setting.