Quantifying Factors Associated With Birth Outcomes and Their Implications on Evaluating the Success of a Maternal Respiratory Syncytial Virus (RSV) Vaccine Program in Kenya

Abstract

BackgroundMaternal immunisation to prevent respiratory syncytial virus (RSV) associated disease among infants is in focus. However, little is known about adverse birth outcomes and associated factors occurring in a setting with high morbidities of malaria, HIV infection and undernutrition. Quantifying these ahead of introduction of a maternal vaccine would assist in assessing an association between RSV vaccination and adverse birth outcomes. MethodsA cross-sectional survey was conducted to collect data on birth outcomes from women residents of the health and demographic surveillance systems (HDSS) of Siaya and Kilifi, Kenya and from the maternity wards of Siaya County referral hospital and Bondo sub-county hospital. Participants of the HDSS sites had pregnancies registered in the years 2017 to 2020 through census rounds and were traced at home for interview. All women had a birth outcome by the time of data collection. Multiple logistic regression was used to determine independent predictors of adverse birth outcomes. Results A total of 2219 women were interviewed. Median age during pregnancy was 27.7yrs (range: 22.7-32.4), 1857 (83.7%) attended antenatal care clinic (ANC), 1,979 (89.2%) delivered at a health facility and 2204 (99.3%) reported they would take up a new maternal vaccine. Adverse birth outcomes occurred in 781 (35%) of pregnancies; 490 (62.7%) were preterm, 247 (31.6%) low birth weight, 189 (24.2%) macrosomia and 42 (5.4%) still births. Predictors of adverse birth outcomes were, eclampsia (AOR 6.86 (1.40-33.60); p=0.017), gestational diabetes (AOR 3.01 (1.24-7.30; p=0.015), and home delivery (AOR 2.48 (1.20-5.13); p=0.014). Being multiparous (AOR 0.52 (0.33-0.81); p=0.004) was protective. Home delivery was significantly associated with older maternal age 40-49 years (p=0.001), multiparous >5 (p=0.001), level of formal education below primary (p=0.001) and Islamic religion (p=0.001). ConclusionsIn this maternal population, about a third of pregnancies have adverse birth outcomes. Recognizing this baseline prevalence will be important in validating safety of a new maternal vaccine. Monitoring of the actual safety outcomes of the maternal RSV vaccine, will require integrated initiatives to mitigate against factors affecting utilization of maternal healthcare services and individual factors associated with adverse birth outcomes.