My friend got cancer while she was pregnant. She had cancer in her teens so this wasn't super surprising.

Anyone else who’s wondering why… they think age, diagnostic tools, pregnancy hormones, and environmental factors. I remember seeing some articles a few months ago fly around that women across the board are getting cancer earlier and earlier though, wonder if there’s overlap.

Why are cases like this rising?

The broad range of cancers presenting during and after pregnancy suggests a variety of contributing factors.

In high socioeconomic countries women are having children later in life and the biggest risk factor for many cancers is increasing age. However, the evidence for age being a major factor in pregnancy-related cancer is inconclusive. This may account for some but not all cases.

Another factor may be the rising use of prenatal genetic screening tests in early pregnancy. These analyse DNA derived from the mother’s blood to detect chromosomal abnormalities in the developing fetus. But these tests can also give information about the mother’s chromosomes. This has led to diagnoses of Hodgkin disease, breast and colorectal cancer in pregnant women without symptoms.

Oestrogen and progesterone are two hormones important for growth and development of breast tissue and to support other aspects of a healthy pregnancy. These may also contribute to cancer development, particularly breast cancer. However, it’s not clear whether this is linked to rising rates of pregnancy associated cancers.

Other cancers, such as skin cancer, are associated with environmental factors such as UV exposure. Notably, melanoma was the leading pregnancy-associated cancer in the NSW study, reflecting the high rate of skin cancer in the local population. Other environmental factors, such as smoking and human papillomavirus, are associated with cervical cancer. Again we’re not sure whether such factors are linked with rising rates of pregnancy associated cancers.