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Genetics Affect What Age Women Have Their First Child

Genetics Affect What Age Women Have Their First Child Find more genealogy blogs at FamilyTree.comWant to do something a little different with your genealogy research? Figure out how old your female relatives and ancestors were when they had their first child. A study reveals that genetics plays a role in what age a woman will have her first baby and the total number of children she will have.

Many women are waiting to start their family later on in life. There are many reasons for this. Today’s women have more opportunity to have a career than their grandmothers did. Some women are postponing pregnancy until after they have finished school, or established a career. Improvements in contraceptions help make that possible.

A study done by Oxford researchers reveals that there is a clear genetic component that is linked to the age of mothers when they have their first child and also in the total number of children she will have. In other words, the non-biological explanations for delaying motherhood have a bigger role than do the social or economic reasons.

The study did not identify specific genes that may be associated with having children earlier or later in life. The researchers are working on a follow-up study that might shed light on that. They do know, however, that it isn’t one particular gene at play. Instead, it appears to be a combination of genetic variants that cause a woman to be more prone to having her children earlier, or later, in life.

The researchers suspect that at least some of that combination of genes affect fertility. Women who are less fertile than average will typically take longer to get pregnant than would women who were more fertile. The researchers also suspected that other, unrelated, genes might affect a woman’s propensity to stay in school longer. The women who lacked that gene might start a family at an earlier age.

The researchers expected to find that over time, more children would be born with genes that favor younger motherhood. Over generations, women would be having their first child at a younger and younger age.

It turned out that the researchers found a different result than expected. Women are not having children at younger ages than their female ancestors did. Instead, women today are waiting to start their families at an older age than their female ancestors did. The researchers suspect this means may signify changes in fertility over time.

The average age of first time mothers has gone up since the middle of the 20th century. In 2012, the average age of first time moms in England and Wales was 28.1 years. In 2013, the average rose to 28.3 years. It may not sound like a lot, but over time, that small increase grows to a big one.

Image by mbtrama on Flickr.

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