Risk factors for major external structural birth defects among children in Kiambu County, Kenya: a case-control study

Background: Although major external structural birth defects continue to occur globally, the greatest burden is shouldered by resource-constrained countries largely with no surveillance systems. To the best of our knowledge, few studies have been published on the risk factors for these defects in developing countries. The objective of this study was to identify the risk factors for major external structural birth defects among children in Kiambu County, Kenya. Methods: A hospital-based case-control study was used to identify the risk factors for major external structural birth defects in Kiambu County. A structured questionnaire was used to gather information retrospectively on exposure to environmental teratogens, multifactorial inheritance, and sociodemographic-environmental factors during the study participants' last pregnancies. Descriptive analyses (means, standard deviations, medians, and ranges) were used to summarize continuous variables, whereas, categorical variables were summarized as proportions and percentages in frequency tables. Afterward, logistic regression analyses were conducted to estimate the effects of the predictors on major external structural birth defects in the county. Results: From the multivariable analyses, maternal age ≤34 years old, (aOR: 0.41; 95% CI: 0.18-0.91; P=0.03), and preceding siblings with history of birth defects (aOR: 5.21; 95% CI; 1.35-20.12; P =0.02) were identified as the significant predictors of major external structural birth defects. Conclusions: Maternal age ≥35 years old, and siblings with a history of birth defects were identified as the risk factors for major external structural birth defects in Kiambu County, Kenya. This pointed to a need to create awareness among couples against delaying childbearing beyond 35 years of age and the need for clinical genetic services for women of reproductive age with history of births affected by congenital anomalies.