Medical resources are generally stretched during holidays (including weekends) due to factors like staffing and hospital policies. This may amplify holiday effects: disparities and variations of health outcomes between holidays and weekdays. Dr. Sassa and colleagues studied this holiday effect with a focus on birth, especially high-risk births as measured by babies born preterm and/or with a low birthweight.

The authors used birth certificate data from over 21 million individuals born from 1979-2018 (which included birthday, birthweight, and gestational age) to categorize individuals into five groups: low birthweight (<2,500g), preterm birth (<37 weeks), low birthweight and preterm birth, and full-term birth. For this analysis, the authors compared weekdays (Monday-Friday) with weekend days (Saturday and Sunday), national holidays, substitute holidays, Golden Week (four consecutive spring festival days in Japan April 29 -- May 5), and the new year period (December 29 -- January 3). Leap days and multiple births were excluded.

They found that all births were significantly less common on weekend or holiday periods versus weekends (p < 0.01). High-risk births became more frequent over the four decades studied, and the trend of non-weekend or holiday births was especially evident for high-risk births, which were found to take place particularly frequently on Thursday and Friday. Though this study doesn't include data on medical interventions or pregnancies that didn't end in a live birth, which could potentially impact the findings, its broad scale suggests medical staff may often control births so that they take place before a weekend or holiday, especially for high-risk births. The authors note that this may be prudent since there are often fewer staff or resources available on weekend/holiday days, but since some holiday births are inevitable, it's critical for hospitals to plan to minimize risks to those mothers who do give birth on non-weekdays.

The authors add: "Delving into decades of birth data in Japan, our research illuminates a fascinating trend -- deliveries on holidays, especially those deemed high-risk, show a distinct decline. This discovery prompts a call for innovative solutions and systemic strategies to safeguard maternal and neonatal well-being anytime, demonstrating the need for creative thinking in optimizing medical resources for everyone."