Trends in Birth Rates, Sex Ratio, and Infant Mortality Rates Among Singletons, Twins, and Higher Order Multiples in...

Area of Science:

• Reproductive Health
• Demography
• Perinatology

Background:

• Brazil has experienced significant demographic shifts in birth patterns.
• Understanding trends in multiple births and associated infant mortality is crucial for public health.
• Regional variations in Brazil necessitate localized analysis of birth and mortality data.

Purpose of the Study:

• To analyze trends in singleton, twin, and higher-order multiple birth rates in Brazil from 2010 to 2023.
• To compare infant mortality rates across different gestation types (singleton, twin, higher-order multiples) within Brazil.
• To investigate regional disparities in birth and infant mortality rates and explore factors influencing twinning trends.

Main Methods:

• Utilized data from the Brazilian Ministry of Health's Live Birth Information System and Infant Mortality Information System (2010-2023).
• Analyzed 39,663,928 live births and 464,843 infant deaths.
• Applied Weinberg's differential method to distinguish between dizygotic and monozygotic twinning trends.

Main Results:

• Twin birth rates increased, while singleton birth rates decreased between 2010 and 2023.
• Infant mortality was approximately five times higher for twins and three times higher for higher-order multiples compared to singletons.
• Dizygotic twinning rates rose significantly, linked to increased maternal age and assisted reproductive technologies, while monozygotic rates remained stable.
• Regional differences in birth and infant mortality rates were observed, with higher rates in the North and Northeast.

Conclusions:

• Brazil is experiencing a notable increase in twin births, driven by dizygotic twinning, alongside a decline in singleton births.
• Higher-order multiples and twins face substantially elevated infant mortality risks, highlighting the need for targeted interventions.
• Demographic shifts, including delayed childbearing and assisted reproductive technologies, are key drivers of changing twinning patterns in Brazil.