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Birth complications at higher maternal age related to age at first period

21 September 2009
Appeared in BioNews 526

Mothers who started menstruating at an earlier age are at a higher risk for complications at birth, researchers from Cambridge, UK report. This means that the higher risk for complications for older mothers identified in other studies may be dependent on the time that has elapsed since their first period, rather than the mother's age per se. These results are to be published in BJOG: An International Journal of Obstetrics and Gynaecology.

The functioning of the womb is controlled by female hormones - mainly oestrogen and progesterone, starting from the first period. It could be that long term exposure of the womb to these hormones makes it contract less strongly during birth, causing the need for a Caesarean section. If this is the case, a mother who had her first period at age ten would have a similar risk of complications at birth at age 35 that a 40 year old mother who had her first period at age 15, as in both cases the womb has been influenced by hormones for 25 years.

The scientists looked at data on the need for Caesarean sections in 3739 first-time mothers and their age at first period, and their findings supported this theory. According to study author Professor Gordon Smith: 'The association between age at menarche [first period] and the risk of operative delivery was no longer apparent when adjusted for the interval between menarche and first birth'.

He also stated that 'the main significance of this study' is not that mothers with early periods have a greater risk of complications, but that it 'sheds light on why advanced maternal age at the time of first birth might be associated with increased risks'. If the cause of this problem really has been identified, this could be a first step towards finding new treatments that could alleviate some of the risk associated with bearing children at a later age. However, as this risk also includes an increased risk of certain birth defects, miscarriage and infertility, late motherhood will most likely remain a controversial issue.

Nevertheless, more evidence is needed to confirm this result. 'This new hypothesis is another piece in the biological jigsaw', said BJOG editor-in-chief, Professor Philip Steer 'Larger scale studies examining different populations are needed to see if the same results are observed. In the meantime, women who have had early periods need not worry'.
Complication risk for older mums
BBC News |  14 September 2009
Early periods' birth problems link
Press Association |  16 September 2009
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