Determinants of the First Birth Interval Among Women in India

The first-birth interval after a marriage indicates the reproduction behavior of women and influences the population's birth rates and size. The present study assesses predictors of the interval between marriage and first childbirth in India.

The study employed the Cox proportional hazard model and Kaplan Meier Survival plot based on the data collected from 79,787 ever-married women in the 15-49 age group from the National Family Health Survey 2019-2021.

The median age of marriage to the first birth interval was 23 months in India. The older marriage cohort had longer birth intervals than the younger. The hazard ratios (HR) showed that the risk of first birth after marriage was much higher among women with higher education (HR= 2.05, 95% confidence interval (CI) = 1.98-2.11) than women without education. Women in urban areas (HR=1.22, 95% CI = 1.20-1.25) had a higher risk of first birth after marriage earlier than women from rural areas. Women from North-east (HR=1.14, 95% CI=1.10-1.18) and South (HR=1.15, 95% CI=1.12-1.19) had a higher risk of having their first birth earlier after marriage than women in the North region. The women who married within 18-24 years of age had a 69 percent higher likelihood of first birth interval than those women who were married below the age of 18. The risk of first birth after marriage increased as women delayed marriage up to age 25 years and more (HR=3.18, 95% CI=3.02-3.35) than others.

The timing of first birth was associated with the age at the first marital union, women's educational attainment, place of residence, region, economic status, exposure to mass media, contraception use, and history of pregnancy termination.