Analyzing waiting time to conception for most recent birth: a probabilistic approach

Maternal and child health is a critical determinant of a country’s development, making it essential to monitor reproductive health outcomes. The conception period is a particularly sensitive phase in a woman’s life, where inadequate care may lead to adverse outcomes. An important indicator in this context is the birth interval, reflecting fertility behavior and maternal well-being. This study estimates waiting time to the most recent closed birth interval using statistical models: the length-biased exponential, length-biased exponential-gamma distribution, modified mixed exponential distribution, and modified mixed exponential-gamma distribution. These models were applied to data from Uttar Pradesh and Varanasi, and further extended to analyze temporal trends using three rounds of the NFHS (1, 3, and 5). Findings indicate that, over the years, the mean WTC has increased, while fecundability has declined across most categories. These trends highlight shifting reproductive dynamics and underscore the need for targeted policy interventions to strengthen maternal and child health services.