A research paper published in the November 2006 edition of BJOG: An International Journal of Obstetrics and Gynaecology reveals seasonal and environmental variations can result in higher incidences of premature births.
An international review of the available literature was conducted, cross-referenced to an analysis of the seasonal variability of preterm births across 18 maternity units over 12 years in the North West Thames region of London.
The review of research demonstrated that seasonal patterns do exist around the world. Results from developed and developing countries were compared. In countries where there are harsher seasonal changes such as the United States and Japan, winter and summer recorded the highest numbers of preterm births. In developing countries, seasonal patterns revealed a correlation between nutrition and maternal weight loss in determining whether babies were born premature. In Gambia for instance, preterm births were recorded twice a year, between the start and end of the ?hungry’ season.
The risk of preterm births in London occurs during the winter between November and December. Unlike the USA and Japan, England’s temperate climate means that the population is not exposed to the same extreme temperatures experienced in those two countries.
The authors also reveal how medical factors present at the time of birth (many of which are seasonal), rather than during the time of conception, may result in preterm births. Risk factors such as genital tract infections, and external environmental factors such as drops in barometric pressure or high levels of atmospheric pollution all contribute to more preterm births.
Dr Sue Lee of the Oxford Tropical Medicine Programme at Mahidol University, Thailand said, ?Our study clearly demonstrated that a seasonal pattern of preterm births exists in the UK with the highest risk of preterm birth occurring in winters. However, the study was conducted in a London-based population only and should therefore not be generalised to the entire UK population without caution.
These findings have potential implications for planning and preparation for preterm births for hospitals and carers.
The next logical step would be to try and understand what is causing the seasonal differences in preterm birth rates so that interventions can be tailored toward using this information to reduce the consequences of preterm birth.?
Ric Warren, RCOG Honorary Secretary said, ?Establishing seasonal patterns of birth can have important implications for the delivery of healthcare services. Anticipating these changes could potentially reduce morbidity and mortality of preterm births.
Preterm birth is one of the largest contributors to mortality in neonates and infants, and to morbidity later in life. Expanding our knowledge of environmental factors is one step towards reducing the frequency of preterm births.?