Monday, May 04, 2015

Too old to have a baby ?

When are women biologically too old to reproduce? This is an important question, because most women today decide to delay having children and the question is: how long can they wait?

The age at which fertility declines to a level where it becomes impossible to conceive a pregnancy in the bedroom leading to live birth is termed with the biological age at last birth (ALB): the age at last birth when no contraceptive measures have been used to limit family size.

In this fascinating paper, ( Too Old to Have Children? Lessons From Natural Fertility Populations
Marinus J.C. Eijkemans, et al Hum Reprod. 2014;29(6):1304-1312 which you can read at http://www.medscape.com/viewarticle/825760_print ) the researchers determined the average Age at Last Birth for over 50000 women by studying historical records. They found that the median age at last birth (ALB) for females is ~40–41 years of age across a range of natural fertility populations. This suggests that there is a fairly universal pattern of age-related fertility decline.

The biological ALB curve can be used as a tool to counsel women who are considering or are actually delaying childbearing. This information will be most beneficial provided the woman is told that the age-related chances of success are averages: for any individual woman these chances may be higher or lower, depending on the characteristics of the woman. The average chance of involuntarily childlessness slowly increases to 12% at 35 and 20% at age 38. From there this chance sharply rises to 50% at about 41 and reaches almost 90% at age 45.

The study reveals several important lessons. For example, for women aged 32–34 who still have a very good chance of bearing children although their risk of childlessness has tripled since age 25 and will increase substantially more after age 35, the lesson is: do not wait much longer, certainly not if you want more than one child. Finally, since the success rate of IVF demonstrates a similar age-related decline as the chance of a natural pregnancy women should also be told that the idea of IVF reversing the effect of age is a mistaken belief.

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