A new research published recently in the journal Heliyon suggests that women who are born in the summer months are likely to grow up into healthy adults. This study involved almost half a million people in the UK. The authors of the study are of the opinion that more sunlight and hence, higher vitamin D exposure in the second trimester of pregnancy could be one of the likely reason for the outcome. However, more research is needed in this area to substantiate the findings.
As per the study, birth weight and the onset of puberty get affected by the birth month both these factors have an impact on the overall health of women during their adulthood. The environment in the womb plays a major role in the early life of women even before birth and can have a significant influence on women's health in later life. This effect is termed as programming and has effects for development throughout childhood and into adulthood.
The researchers from the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge, UK are behind the study and they were keen on finding if birth month had an effect on birth weight, onset of puberty, and adult height. Their study led them to the finding that children who were born during the summer months were slightly heavier at birth, taller as adults and went through puberty slightly later than those born in winter months.
Dr. John Perry, lead author of the study opined that the time when a child is conceived and is born happens largely at random and is irrespective of social class, parent's age or their health. So, looking for patterns with birth month is a powerful study design to identify influences of the environment before birth.
Some previous studies have pointed out to certain effects of the season of birth, like on birth weight and various other health outcomes. Dr. Perry and his team of researchers thought that childhood growth and development, including the timing of puberty, is an important link between early life and later health. That is the reason they decided to study the impact of birth month more closely.
The growth and development data of around 450,000 men and women from the UK Biobank study – a major national health resource that provides data on UK volunteers to shed light on the development of diseases was studied and compared by the researchers. The results of their study indicate that babies born in June, July, and August were heavier at birth and taller as adults. The study also revealed that girls born in the summer started puberty later – an indication of better health in adult life.
Dr. Perry said that it is the first instance when puberty timing has been robustly linked to seasonality. He said that they were surprised, and pleased, to see how similar the patterns were on birth weight and puberty timing. The preliminary result show that birth month definitely has a measurable effect on the development and health. Of course, further study is needed to understand the mechanisms behind this effect.
The factor that can be crucial in deciding the differences between summer babies and winter babies could be a case of how much sunlight the mother gets during pregnancy, as that plays a crucial role in her vitamin D exposure.
Dr. Perry said that the mechanisms that cause these seasonal birth patterns on birth weight, height, and puberty timing is not understood as of now. They need to be before the findings of this study can be translated into health benefits. The researchers are of the opinion that vitamin D exposure is likely to be of key importance are will study the long-term effects of early life vitamin D on puberty timing and health.