This study aimed to identify differences in factors associated with subsequent childbirth between the marriage years of 1996–2005 (Group 1) and 2006–2015 (Group 2) using the 2015 National Survey. A total of 5097 eligible participants (2492 and 2605 women in each group, respectively) were included. The main variables consisted of demographic characteristics, socio-economic status, value for child and son, and social support for raising child. For statistical analysis, discrete-time hazard models were used. The common factors associated with subsequent childbirth in both groups were son preference (Group 1: HR = 1.16; 95% CI = 1.06–1.27, Group 2: HR = 1.14; 95% CI = 1.04–1.24) and the favorable value on children (HR = 1.12; 95% CI = 1.01–1.25, HR = 1.11; 95% CI = 1.01–1.22). Only in Group 2, age at the first childbirth (HR = 1.35; 95% CI = 1.31–1.39) and more monthly income (≥4600, <6000: HR = 1.18; 95% CI = 1.04–1.33, ≥6000: HR = 1.15; 95% CI = 1.00–1.32) were significantly associated with subsequent children. Whereas, working women (HR = 0.86; 95% CI = 0.78–0.94) were less likely to have subsequent children. To increase fertility in Korea, the government must provide childcare and deal with factors associated with low fertility considering the reduction in role incomparability for women due to changes in demographic characteristics.

The aim of this cross-sectional study was to identify the factors associated with different percentiles of first-time maternal fatigue. A total of 123 first-time healthy mothers aged 18 years or older participated through an online survey. The fatigue was measured by the Korean version of the fatigue severity scale. Main variables were constructed based on the integrated fatigue model, which included mothers’ sleep quality, parenting stress, the amount of free time mothers have, the number of the child’s night wakings, general characteristics including socioeconomic status, and working status. Quantile regression was used to analyze the associated factors according to the fatigue level of first-time mothers with a young child. The mean age of the mothers and children were 32.11 years and 20.81 months, respectively. Mean fatigue score was 6.16 among the 75% quantile with high fatigue score. Lack of adequate free time in mothers, advanced maternal age, being a housewife, having a moderate income, and frequent night wakings of their child significantly increased fatigue among mothers in the third quantile of fatigue. To reduce fatigue, healthcare providers should focus on exploring ways to reduce maternal sleep disturbance and improve maternal sleep quality.