Soon, you may find out when you’ll have a baby based on your genetics.

Researchers at Oxford University found this week that genetics matter when it comes to women deciding what age they want to start building a family and how many children they will have, The Guardian reported.

The researchers looked at similarities and differences between women who gave birth at different ages. They found that genetics accounted for 15 percent of the difference in ages for first-time mothers, and almost 10 percent of the difference in how many children they had, The Guardian reported.

“What we see in this study is a clear genetic component linked to the age of mothers when they have their first child, and to the number of children they have,” said Melina Mills, a researcher at Oxford, according to The Guardian.

The study didn’t list specific genes that are associated with this change. But Mills said there’s likely going to be a follow-up study that will look for those specific genetic factors.

“It’s not one gene, but a combination of genetic variants that makes you more prone to having your children later or earlier,” Mills said, according to The Guardian.

Over time, Mills said, this will help researchers understand why certain women delay having children until their bodies are less likely to give birth.

“We are having our children when we are least biologically able to have them. Why are people postponing? What are the genetic and social drivers, and how do they interact?” Mills said.

Genetic testing is common among pregnant women. In fact, more than half of pregnant women have prenatal screenings that include genetic tests to see what potential dangers could surface during pregnancy, Time magazine reported.

“The vast majority of women undergo carrier screening based on their ethnic background, although many, regardless of their heritage, are also screened for cystic fibrosis,” Time reported. “Traditionally, certain ethnic groups — especially Ashkenazic Jews of Eastern European descent — have been advised to consider carrier screening for various fatal conditions including Tay-Sachs and Canavan diseases.”

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Some couples, though, are less enthusiastic about genetic testing since they worry about receiving negative results, according to Live Science.

“If a pregnant woman chooses to have genetic screening, there is a possibility the results could come back abnormal,” Live Science reported. “[A] lot of women don't go through that thought process before getting screened but need to.”

Live Science suggests that pregnant women get genetic testing as early as possible so they can make necessary plans and do more research about their baby’s possible conditions. Women are often given the option of genetic testing during the first month of pregnancy.

Herb Scribner is a writer for Deseret News National. Send him an email at or follow him on Twitter @herbscribner.

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