Why Are Cancer Rates Rising for Moms-to-Be?

Pregnancy-associated cancer refers to any cancer first detected during a woman's pregnancy or within a year after delivery. Pregnancy-associated cancers are rare, but rates are rising, according to a new study from Australia. And now researchers are scrambling to explain why.

The University of Sydney study looked at health data from approximately 1.3 million pregnancies that took place in Australia between 1994 and 2008. In 1994, researchers determined the rate of pregnancy-associated cancer to be 112 cases for every 100,000 pregnancies. By 2008, however, the cancer rate had jumped to 192 cases per 100,000 pregnancies. Breast cancer, cervical cancer and melanoma (skin cancer) were among the most common types pregnancy-associated cancer detected.

What's driving this uptick? At first, researchers thought that because more women are postponing pregnancy into their 40s, it would make sense that cancer rates—since cancer risk increases with age—would also rise. But when they checked the ages of women in the study who were diagnosed with cancer, "advanced maternal age" could only account for 14 percent of the increase.

But there's another idea at play—one that researchers say makes a lot of sense. Pregnant women receive more and better health care than ever before and it could just be a matter that all those prenatal checkups are giving doctor's a chance to catch subtle symptoms and signs of cancer that could otherwise be overlooked.

"Pregnancy is a time when a woman comes into contact with healthcare workers more frequently than normal and this may play a part in certain cancers being picked up more," notes John Thorp, Deputy-Editor-in-Chief of BJOG: An International Journal of Obstetrics and Gynaecology, the journal in which this study is published, in a separate editorial.

Mom-to-be Katie White of Liverpool, New York, agrees that frequent prenatal checkups provide women with a chance to learn a lot more about their health. "There is so much poking, prodding, and blood tests! By my second appointment, I found out that I am allergic to eggs. Who knew? I am thankful that I didn't have to deal with a cancer diagnosis, but it's kind of comforting to know that my doctor is looking out for this kind of thing."