Lakshmi Hegde of New Britain.

A new study out of the University of Cambridge, published in the journal PLoS One, shows that the most robust findings came from a genetic method called microarray analysis. The study, led by Dr. Andrew F. Fux of the Cambridge Centre for Reproductive Physiology, investigated whether differences in female-biased genes are associated with an earlier pregnancy, when the embryo has already developed into a fetus. “This work offers a genetic analysis that might be used to guide women on how to best decide whether or not to have an earlier pregnancy,” said Dr. Fux.

For the study, Dr. Fux and his colleagues collected gene data from nearly 1,500 pregnant women in their 20s. They asked a total of 447 of them to provide an informed consent to perform one of two tests. The first test, which relied on sequencing the entire genome of the embryo and comparing it to a database of embryonic mutations, led to what is called a “true” association between a genetic marker and the decision to have an early pregnancy.

In contrast, the second test used microarray analysis to identify specific genes associated with an earlier or delayed gestation. One hundred and five of these genes showed such a clear and significant association with delaying the timing of a pregnancy that the researchers decided to publish this finding. In another paper published by the lab this past March, they examined the genetic results from more than 600 unrelated women and compared the results of either the early pregnancy test or the microarray to that of their mothers.

There were still enough women in the study who refused to enroll in the study that the researchers could not extrapolate from those results to the whole population. However, this is proof that an association can be found even among women who refuse to be included in the study. “There are still many women who are reluctant to participate in research studies, and this experiment shows that there really is an overlap between women who are unwilling to participate in these studies and people who might be most suitable to be included,” said Dr. Fux.

However, the test also showed that genetic differences between nonparticipants and participants could not be detected as predicted by the genetic method. Researchers found that the test missed about a third of the genes that were associated with either early or delayed pregnancy.